The Great Trifexis Hoax: 6 Ways to Spot the B.S.

What if the “medicine” you were given to get rid of fleas, ticks, and heartworms in your dog turned out to be toxic and was causing poor Sadie’s liver, kidneys, and skin to go into overdrive, trying to keep that poison from bringing her to her knees?
Not a pretty picture, but there continue to be many reports of deaths and illness coming in from owners after the use of this drug called Trifexis.

What is Trifexis?

Made by Elanco (a division of Eli Lilly and Company, the  global pharmaceutical manufacturer with sales in the billions), the drug is a combination of two drugs found in other products:

1. Spinosad, a pesticide sourced in the United States, the main ingredient in Comfortis, the flea killer, and

2. Milbemycin, a pesticide sourced in China (per Dr. Connell, the vet on staff at Elanco), and the main ingredient in Interceptor, the heartworm larvae killer.

Here’s a map of Lilly’s plants around the world:

World map, red indicating Lilly manufacturing plants

Oh, my! Isn’t that China over there?

If you live in Canada, the UK, or Australia, your version of Trifexis is called Panoramis.  And, if the name Trifexis scares you, you can get the very same product now under the name Comboguard.

What’s Happening to Real Dogs after Taking Trifexis?

Of course the whole idea of giving pesticides to animals is a bad idea, right? How could they possibly make an animal healthier? Well, some folks missed the memo apparently, as Elanco has sold well over 50 million doses as of November 2013.

Update: According the Indy Star’s report on veterinary pharmaceuticals (and how wildly unregulated that whole world is), the company said they’ve sold over 70 million doses. And that’s 2013 data. How many more have been sold since then?

Some of the most striking conversation is taking place on the AVMA (American Veterinary Medical Association) website itself (this page has been taken down, sorry), though there is a a special Facebook page with lots of concerned pet owners who have lost animals or had animals sickened after taking Trifexis. In addition, Atlanta station WSB-TV has a couple of stories from late 2013 on problems post-Trifexis, including deaths, and Elanco’s response (“the drug is innocent, no correlation”).

Reports from real people with experience from their own animals include:

  1. Failure of the product to rid hook worms (part of its label claims).
  2. Refusal of the subsequent doses by dogs who got ill on the first dose.
  3. Blindness immediately post-Trifexis dose, from detached retinas.
  4. Death. (By some counts in November 2013, some 700 dogs were alleged to have died from ingesting Trifexis.)
  5. A vet who’s seen harm first hand in his patients, reported it to Elanco, and pulled the product from his shelves.
  6. Vomiting, a very common side effect by the number of reports.
  7. Pancreatitis.
  8. “Fly biting,” an air snapping behavior common in epileptic dogs.
  9. Seizures.
  10. Confusion, restless wandering.
  11. Weakness in rear limbs; paralysis.
  12. Heart disease.
  13. Lethargy.
  14. Hypersensitivity, acting as if suddenly bitten. Touchy.

What’s striking in all these many, many reports is that, while some of them came on after the first dose (including deaths), many came on after months of use or even a year.

How to Recognize the B.S. : Six Ways

Elanco, and the AVMA right along with them, are spinning the story that tries to tell all these people that their animals who either died or got paralyzed or went blind right after taking Trifexis have no reason to blame the drug. This is largely based on necropsies (think autopsies on animals) reviewed by  an “independent pathologist.” That’s a very good place to start.

The “independent” veterinary pathologist is Jeffery Engelhardt. He was hired by Elanco to review necropsy reports on three Visla pups who died within days of ingesting Trifexis. This man has a prior history of working for Eli Lilly, the parent company, for over 20 years.

Interestingly, there were seven pups in this litter. The three that got Trifexis all died, while the four who didn’t never even got sick.

Are you raising your eyebrows yet?

So, we have

  1. B.S. Point One: The “proof” was provided by someone with ties to the manufacturer reviewing the work of other pathologists.
  2. B.S. Point Two: Study samples to get a new drug labeled are by necessity small. Their findings (no deaths) don’t negate what hundreds or thousands of pet owners are seeing in their dogs (illness and death).
  3. B.S. Point Three: A necropsy on three dogs showing heart disease does not let the drug off the hook as the cause. A vet contacted at Elanco admits as much.
  4. B.S. Point Four: Necropsy results of a poisoned animal are “non-specific.” In other words, they could be anything. Organ failure would rank high but there’s no way to see a “footprint” of Trifexis poisoning, and, absent that, say it was not to blame. There’s an old saying, “You can’t prove a negative.”
  5. B.S. Point Five: Poisoning (with anything) is most often the presumed diagnosis based on history of ingestion and symptoms showing up as a result. Pathology could vary widely.  So, somewhat like #4, necropsy findings alone cannot be used as a defense in a poisoning case.
  6. B.S. Point Six: Elanco set out to look for another cause of death. An Elanco vet is quoted as saying,

What we look for are underlying causes, pre-existing conditions – any other indication that the dog had any other reason for dying.”

So, the very starting point in interpreting the necropsies, as you can well imagine, is biased. They sell this drug, they would rather not incriminate it as the cause of illness or death. They’d rather avoid the cost of pulling it off the market and reimbursing the likely thousands of people who would make claims against them.

So, What to Do?

The clear take away from all of this is simple. You need to be a smart consumer. Keep your ear to the ground, and if you hear hoof beats, and you don’t live in Africa, expect they were made by a horse, not a zebra.

Just as you’ll never convince a mother who lost a child to vaccine induced autism by telling her there’s no conclusive proof, neither will you be able to dissuade thousands of animal owners who’ve seen illness or death after giving a drug, that the drug was not responsible.

You need to raise Vital Animals, who can withstand the vagaries of life, and you won’t get there by using pesticides to kill fleas, worms or heartworms.


Pesticides are poisons.

For a drug-free alternative that’s been working to prevent HW safely for over 20 years, click here.

Picture attribution: Wikimedia Commons

Map attribution: Wikimedia Commons


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  1. L. Restivo on January 15, 2024 at 3:37 pm

    I have not read through all the comments, so forgive if this is redundant. Had a rescue with ‘celiac disease or something similar to it.
    Dr.s orders to keep him on a homemade organic diet. Mostly Chicken, sweet Potato, pumpkin, peas, ground eggshells, chicken bone broth.
    I also put a capful of ORGANIC Apple Cider Vinegar in his drinking water. This kept his mouth bacteria free, ( very little mouth odor or gum disease), MOSQUITOES at bay, TICKS at bay therefore if heartworm is mosquito attached parasite, never EVER gave him a heartworm pill.
    I gave him one full squeeze of that smelly topical flea stuff, while reading it’s warning label (keep away from children, etc.) asked myself WHY in the world would I subject this poor guy to more crap? Needless to say the next morning his breath stunk of that chemical, and he was lethargic and mopey. You all DON’T NEED a Dr. to SEE… I never gave him another chemical soup again. Clue, when in doubt DON’T.
    Also I use a natural peppermint spray which I keep by the front door, before we go out, my new pooch gets a spritz and rub-down.
    Easy Peezy. BTW my first guy lived to 20 years of age. NO MEDS.

  2. Mechelle on February 4, 2023 at 10:56 pm

    Alternative for fleas in the deep south? I don’t want to give my animals poison. The last dog I had lived to be 18 I adopted her when she was nine. I’ve never been one didn’t want to keep them on heartworm medicine because we don’t go out a lot My dogs are indoors and I’m not a big outdoor person they play in my house they exercise in my house we go to the dog park occasionally. I have been alternating months with comfortis. But I don’t feel good about it. But you know when my older dog died now I have two more I could I couldn’t even get another dog because the shelter lady over the small dog shelter wouldn’t let me adopt one because I didn’t have my older dog on heartworm protection and she didn’t die from heartworms she died from kidney disease and she was 18 years old. They even go back and look at your record it prevents you from even being able to adopt another dog. But what is an alternative for heartworms and fleas what can we use that’s going to work here in the south cuz the fleas are bad. And I’m leaving an apartment and I like to take my dogs different places I can’t treat everyone’s yard. Just wondering.

    • D. Archer on March 1, 2023 at 3:26 am

      I’ve used topical Revolution flea/heartworm Rx on my dog for 9 years (in Santa Cruz, CA and we have wicked fmeas here). It’s always worked great for me.

      My vet told me the topicals work as well as the pills that are ingested, but topical Rxs don’t expose the dog to as much chemical/s as pill flea Rxs do.

  3. Kris Gathier on January 10, 2023 at 11:46 am

    Here’s the question you all should be asking yourselves if you think all these “drugs” are just fine and “safe” to give your innocent animals, and I’ll assume you all love your companions. Would I ingest these drugs myself? Don’t go further than that. Just answer the question. Would you? If you would, then may I suggest you do so and see how you fair but have pity on the animals. Big pharma doesn’t care about your companions; only the money. Scripture tells us that the LOVE of money is the root of all evil.

  4. Alicia B. on July 9, 2022 at 2:33 am

    After reading all this input I am still left with questions. I have 2 Chihuahua’s (mother 12yrs & daughter 10yrs) and have been giving them both Trifexis for years. In the beginning the med worked very well overall and including as a flea defense. The last few years I have noticed that my older dog becomes very loopy and disoriented with lack of appetite within a couple hours of administering the med. Also I notice that the flea protection seems to wear off after 3 weeks. Mind you we live in SOFLO so the weather and bugs are on 1000 throughout the year (especially during spring and summer) .. I expressed my concern of the older one’s side effects to my vet and he stated he does not believe it is related to the drug and suggested that I try 1 called Simparica… I guess I am just looking for more input.

    • Laura on October 18, 2022 at 12:31 pm

      Simparica is a pesticide. You would not give that to your dog. Even the FDA says it is associated with neurologic adverse reactions including muscle tremors, ataxia, and seizures. Traditional vets are playing with fire at the expense of our dogs. Please use nontoxic parasite products, there are many you can google online.

  5. Kimberly Bowden on July 24, 2021 at 1:36 pm

    THANK YOU so much for this! My dog is supposed to take this once a month (and the dosage is for dogs 20-40 lbs. (my dog is 25 lbs and now I wonder if that means he’s getting even more than he should since he’s 15 lbs less than 40).
    He’s been taking it for a year and hasn’t thrown up yet. But he detests it. He’s also a very anxious dog. More so than any other dog I’ve known. He’s always on high alert and constantly moving. He’s not big on being touched. This might explain it.
    My husband takes him to a well-known pet store, with their own vet, as that’s where his parents took their old dog (and they liked that veterinarian). They used to have a Cavalier King Charles (in the same family as Cocker Spaniels) and somewhere around 9 or 10 years old, he started losing his vision and became confused a lot. I believe, towards the end of his life at 11, he was having seizures as well. I’m pretty sure he was taking the same medication since he went to the same vet.
    This sheds A LOT of information on everything. I’d be willing to bet that the vets do this to make more money for themselves. How sad.
    As for my own experiences- I’ve never taken that drug but I’ve taken something similar when I had a bacterial infection a few years ago. My Dr gave me Metronidazole which is not only used for bacterial infections but it can treat parasites as well. Even though they aren’t the same drug, Trifexis and Metro both kill parasites. I can say, from experience, that Metro is a HORRENDOUS medication. I’ve never taken something that made me feel so sick. It made me weak, tired, nauseous and gave me headaches. There were a few times at work that I had to hold on to a counter because I was dizzy that I felt like falling over. That drug is considered to be carcinogenic (cancer causing). I’d be willing to bet that Trifexis is too. Its basically squashing everything out of your stomach. That can’t be a good thing to do 12 times a year for life. This is terrible!
    Thank you for your wonderful information! I wish more ppl knew about this.

  6. Carolann on September 29, 2020 at 6:36 pm

    To all those who argued that big Pharma and the FDA removes harmful medications from the shelves here is a perfect example why they do not:

    If aspirin was just discovered today you would need to have a prescription due to the side effects. Since aspirin has been used for over 200 years they will not remove it from the shelves.

    Many children have died due to complications while infected with Chicken Pox….aspirin for their fever caused multiple deaths (Reye’s syndrome) Now it is listed on the box or drug information not to use for reducing fever if a child has chicken pox.

    There are other numerous reactions due to aspirin there is a long list, but this one should raise a question of why this medication should be by prescription only: “during pregnancy may have adverse effects in the fetus. It should be used during pregnancy only when the benefits outweigh the risks. Aspirin is excreted into breast milk and may cause adverse effects in the infant. Consult your doctor before breastfeeding.” (this link shows other side effects on this drug.

    When the first heart wormer became available the medication had adverse affects on certain breeds such as collies. Thus, having a mixed breed dog with collie bloodlines may or may not result in an adverse reaction to the drug; thus the dog owner should have a frank discussion with their veterinarian regarding the risk potential.

    • Kimberly B on July 24, 2021 at 2:14 pm

      SPOT ON! This is why Drs always recommend Tylenol over any other pain killer. None of them are technically safe if you use them too much, but Tylenol is considered the safest. Also- Aspirin isn’t meant for children at all.
      One last point (which is a BIG one)- is it’s link with the Spanish flu of 1918. It’s been documented that many ppl who were sick, took Aspirin and died. Aspirin may have caused their death due to it being a blood thinner (which affects your bodies blood-clotting ability). After the 1918 ‘flu’, ppl were considering suing Bayer over these Aspirin-related deaths. But somehow the lawsuits disappeared and everything was forgotten about. This shows EXACTLY how much Big Pharma is protected and should be considered unethical!
      This is why a lot of ppl don’t know what to make of the pandemic we have right now (that started late 2019). We are repeating the same mistakes again and no one knows what works and what doesn’t. It’s all a guessing game at the expense of ppl’s lives.

      • VP on March 30, 2023 at 10:39 am

        Tylenol kills the liver cells and it is highly toxic, not to mention it is made with human embryo cell line.

  7. User3rr0r on June 30, 2020 at 8:02 pm

    My beagle has been taking Trifexis since 2013 so she would have been 5 at the time. Now she’s a healthy and still very active 12 year old. The question you need to ask yourself is if my dog is an outlier or the norm.

  8. Bob on January 2, 2020 at 8:18 am

    This entire article is a bunch of bs. Very similar to vaccinations cause autism in kids. Certainly your right to believe a Facebook page. We all know how reliable that is.

  9. Richard on November 13, 2019 at 1:42 pm

    I like your site, well written, nice format. Only thing that has me wondering is if this is all true why are you charging so much for a .pdf, the Heartworm Prevention Guide, over $50 for access to your .pdf? I don’t disbelieve you just it makes me wonder when you are grossly profiting from your view points. I guess we all need to make a living so it’s understandible. But I’d be more confident in what you were saying if your guide was more reasonably priced. Frankly, if it was me and I care deeply for animals, I’d be giving that guide away for free to everyone, and shouting about it from the rooftops. Lets see if you publish my comment. And no I don’t work for Eli Lilly or something, I’m a retired environmental scientist.

    • Will Falconer, DVM on December 1, 2019 at 10:49 pm

      Hi Richard,

      I’m in business and have expenses like anyone else who is. It takes dollars to keep a site running, pay my staff, and invest in the innumerable pieces of tech that I use. You always have the option to consume a ton of free information here on the site and you have the option to buy products from me. 100% your choice.

  10. Tina Darby on June 29, 2019 at 10:17 pm

    My bichon died in 2014 after Trifexis. I wish I’d never given it to her! She started having seizures and the vet said brain lesions. She had been very healthy prior to taking Trifexis. After she died I started hearing of the other dog deaths. I miss my sweet baby.

  11. Rusty Bosley on May 16, 2019 at 3:06 am

    So my dogs been on Trifexis for about 2 yrs now. She has had some of the side affects mentioned in the comments so I’m taking her off of the medication. It didn’t help her flea problems anyway because she continued to itch even after I gave her a dose of Trifexis. So my question is…. what is a safe alternative for treatment of fleas? We live in Texas so the flea problems are ridiculous. I also want to protect her from other parasites including heart worms. She lives inside full time with the exception of potty breaks outside of course.
    Thanks for sharing,

    • Will Falconer, DVM on May 21, 2019 at 6:52 pm

      Rusty: flea control without poisons:

      • Virginia on January 12, 2023 at 10:01 am

        What do you think about food grade Diatomaceous earth brushed into carpets and lightly rubbed into backside of the fur coat and feet? I use borax for many cleaning and foot soaks. As a halide compound, it help kicks out fluoride from the body. Personally, I give my dog the same mountain valley spring water and distilled water that I drink…never tap water. But my question is: because my little guy is a Dachshund, hound family, he sniffs constantly. What are the complications of sniffing up borax or Diatomaceous earth after it’s been applied to carpeted areas? Both can be ingested rather safely, my main concern is those fine powders into the lung tissue, through inhalation.

        • Will Falconer, DVM on January 18, 2023 at 7:07 pm

          Hi Virginia,
          I’ve never been a fan of DE except in the garden. As it kills its insects by etching their chitin exoskeletons and causing dehydration, imagine how that might feel rubbed into skin. Ouch.
          My understanding is this is not an inhalation risk, though concerns seems to persist on the internet. The old saw about “food grade” vs “pool grade” I think was even laid to rest some years back. Particle size is such that DE is cleared from the lungs normally, unlike asbestos fibers, for example. And borax is even larger, so I don’t expect any lung issues at all with it.

  12. Deanna Bates on May 6, 2019 at 7:21 pm

    Very interesting article. Even though I live in Southern CA my latest dogs have never had fleas not one time. Yet when the dogs went for their annual checks we were offered many of these kinds of products and all these toxic substances never made sense to me. My dogs are 9 and I just recently lost Desy. In the late 90’s I did use some topical flea products but that was before I learned about big pharma, our food, water etc. I research a lot of things and I have tried to be the guardian of my Maltese dogs as they are vulnerable to the greedy stupid actions of humans. I personally haven’t been to an MD in 10 years and I am done with vetrinarians. They poison your pets and you are left blaming yourself for their illness or death. They all have this little cliche thing on their bills about how they understand your pet is like family. That is a lot like the IRS apologizing for any inconvenience you may have experienced.

  13. Nora on February 5, 2019 at 5:11 pm

    I have a 12 almost 13 year old pug that I started on Trifexis 7 years ago. I didn[‘t put the two together but about a week into it he was spinning in circles,loss of appetite, etc. My vet assured me it could NOT be the Trifexis since her animals are on it and she has had no problems. Well, I took him (pug) off the Trifexis after about 6 months and also…. the spinning stopped. The appetite came back, his labs were better…..
    I cannot prove it but my gut told me that the Trifexis was a problem. We live in Texas so the fleas/mosquitos are horrific. Ya’ll are not crazy. I know two folks whose elderly dogs both died after being given TRIFEXIS. …………………. Again the vet said it was a coincidence. REALLY???????
    My pug also has not had anymore seizures since I stopped the Trifexis and he is no longer on Valium for them.
    I realize this is not concrete proof but sure does make me wonder if the Trifexis is safe???

  14. Angela Greene on December 11, 2018 at 7:36 am

    My 17 year old chihuahua has been taking Trifexis for 5 years. That is about the time she developed deafness and lameness in her back end and I thought it was a sign of old age. After her last dose on 11/5 she has had 6 seizures and developed pancreatitis. Of course the dr’s say it is unrelated and offer no help. They just say she’s getting older and they want to give her more drugs. Also her lameness in her back end, confusion and restlessness are getting worse. I of course have discontinued use of that poison. How do I help her with her seizures and other symptoms?!?! HELP!!!!

  15. marline sexton on November 20, 2018 at 9:31 am

    So .o only came on to find out if it were safe to give my dog comforting plus. He was recently diagnosed with pancreatitis. I have learned so much. He has been taking comforting for years . But the comforting plus only about a year now. All his organs are normal not likeany dogs with pancreatitis. The vet was surprised at this. Any advise on a safe flea heart worm med for dogs with pancreatitis ?

  16. Jack Swagger on November 13, 2018 at 9:38 pm

    vaccine induced autism, really, so now all on the anti vaccination wagon too just because a few more kids are coming out on the spectrum, certainly nothing to do with all the garbage in human foods these days…..let’s blame the vaccinations that have been fine for however many years hmmm

    • Jessica on October 9, 2019 at 2:16 pm

      Preach, Jack, preach! Statements such as those in the article are both harmful and ignorant. As an autistic mama with an autistic son, I’m appalled by the comments.

  17. Ellen Sebast on September 11, 2018 at 10:13 am

    Hi, I live SW Florida and feed my German Shepherd raw food. I was told by my vet that there are so many cases of Heartworm Disease in this area. He basically begged me to give him at least regular Heartgard every 45 days. But isn’t getting his blood checked 3 or 4 times a year a better approach? Thank you.
    Ellen S.

  18. Susan on July 11, 2018 at 2:23 pm

    My 3 dogs received comfortis plus last month. It is now time for another dose but not from me. My 2 dogs had bloody stool for 2days and my 12 year old had BLACK watery stool for 4 days, and throwing up blood clots. Took her to the vet and they said she had very low red blood platelets, severely dehydrated & had to be given 7 different meds ( antibiotics) anti clotting agent & special foods. They said she had 7 – 10 days to live. I thank GOD we caught it in time. The vet says no it wasnt the flea meds but why did my 2 dogs have the same symptoms? I blame it on the flea meds because it happened the day after she took it. From now on I will be using a natural flea meds from our local feed store. …….NO MORE PESTICIDES IN MY DOGS( family)

  19. Shielah on January 26, 2018 at 1:01 pm

    So what do you give them to prevent heart worms then?
    I would like to know a straight answer than having to read a book.
    I have an Aussie that will be 2 in May, she was treated once with revolution when she was a year before I knew, haven’t done heart worm since, nor distemper as she tested immune did the dog park for Pavo but haven’t retested yet.

  20. krista on December 2, 2017 at 2:27 pm

    Hi Dr,
    My dog was just diagnosed with whipworm, she’s 2 years old. The vet suggests interceptor plus but is there a natural way I can treat her?

  21. Tammie Jones on October 20, 2017 at 11:25 am

    I just had a conversation with my vet about Trifexis. She had prescribed it for my 10 month old mini Dachshund(10 pounds) and told me over the phone about the side effect of vomiting. I was in the car, she was busy and I didn’t ask questions at that point, but something made me feel very uncomfortable at the moment about giving this to my Cooper. SO….I did a little research before giving him the medicine…and I did not like what I read. I have not given this to him and today I called her to discuss it with her and felt very cut short. She basically told me that I was ignorant (I know she meant no insult) when it came to side effects and after she talked on for awhile I finally interrupted her and said that I should have not said side effects but long-term effects. I told her what I had read to which she said everyone has an opinion. She did not have an answer for the death rate. I don’t even know if she is aware of it. I asked her about alternatives and she said the only alternative to treatment for fleas, ticks and heartworms was to keep Cooper in a bubble. We take him lots and lots of places. He is a very social dog.
    I felt cut off and unheard. I would prefer a holistic vet, but there is none in my area. I have tried to read about alternatives, but do not feel educated enough and confident enough in the products that I read about to feel I am keeping my dog safe.
    Another issue is that this vet is a member of the church where my husband pastors and I am Children’s Ministry Leader and take care of her children. She is young. Recently graduated. BigPharma educated. About 4 years in practice.
    What do I do?

  22. Ben Hu on October 2, 2017 at 4:38 pm

    My neighbor said her dog got sick from Comfortis but I’ve had my two on Trifexis for at least a couple of years and have seen none of the symptoms described above. Is it possible that some dogs tolerate it well and others do not? If I’ve had no problem in all the time I’ve been giving it to them, should I still worry that something terrible might happen in the future?

    • Will Falconer, DVM on October 3, 2017 at 6:06 am

      I’m sure it’s possible many tolerate it, Ben. Just like the alcoholic smoker who makes it to 90 years old, we all have different levels of reactivity. I’d be concerned to continue use though, certainly. Pesticides don’t make one more healthy, right?

  23. Brandon on July 27, 2017 at 2:21 pm

    My Vet gave our new puppy her first free dose and after this one I am no longer going to allow her to give her anymore of this medicine. I am so scared at this point and going to monitor my dog. This is very concerning and I hope im fortunate that I decided to read reviews, unfortunately she already had her first dose and I was planning on purchasing more but nevermind.

    • Will Falconer, DVM on July 27, 2017 at 2:27 pm

      Hey Brandon,
      If this just recently happened, if you want to be proactive, preventing potential illness, grab my Homeopathic Detox Report. Cheap insurance.
      I applaud your decision not to bite the hook that would have you keep buying this stuff. Eesh.

  24. Ray on June 16, 2017 at 7:09 am

    Sammy is Gone!!! He’s been a guinea pig for Trifexis. We have been giving him this toxic poison for over 5 years to treat ticks and fleas, after it was recommended by the humane Society. We did read the side effects, but nothing was mentioned about about paralysis. We started him on this poison when he was about 2 years old. There were periods of vomiting. During his first year of being on Trifexis, he was constantly thirsty, always drinking water. He started to suck on his tongue, and he became fatigue. He would gnaw on his paw. The tongue sucking never went away. He became paralyzed. It happened rapidly. We noticed him missing a step when walking about a month before he became completely paralyzed. We took him to the animal hospital, hoping that the vet would recognize the symptoms, but instead was hit with all types of recommendations for testing which would have resulted in thousands of dollars and no guarantee. In fact, the vet did not even acknowledge our statement about Trifexis.

    • Will Falconer, DVM on June 16, 2017 at 12:50 pm

      Hi Ray,
      I’m so sorry you lost Sammie. Drugs that poison by way of paralysis of the pest (which all the HW “preventatives” I’ve studied do) won’t surprise us when we see nervous system symptoms in our beloved animals.
      Those could be mild, like tics and tremors, to severe, like seizures or paralysis. And, as Sammie showed us, the interval of when the side effects show up can vary all over the map. Some right away, even some deaths after the first dose.
      Sammie held out for 5 years (strong, vital animal!) until he no longer could. I’m so sorry for your loss. And hope Sammie can inspire you and many others to think differently about truly protecting our animals from pests. The key is how we choose to do that.

  25. Joyce Beckett on May 16, 2017 at 10:24 am

    I wish I had been more informed about trifexis last fall – my daughter was watching my two puppies (9 & 10 months) while I was going through some health issues, the vet recommended trifexis because they had such thick coats (Chow Chows) – they were both dead within hours of taking it – (I have a new puppy due in June/July and will not make the same mistake again-and am looking for a new vet!!). You can be sure I am reading every email you send

  26. Carol on May 2, 2017 at 3:26 am

    I gave my Yorkie his Trifexis at 4:30 this afternoon, he woke me up at 2:00 trembling and holding his head back and wanting me to hold him. I took him outside and he was acting really anxious, kept licking my face. So I gave him a Benadryl. It is 3:15 and he has settled down! I have 3 Chiweenies I give this to also! I am afraid to give Trifexis to them now! I will stay up to watch my baby! What to do about this? Stop all this poison that are hurting our babies? They have no fleas or heart worms ! They love to dig in the dirt!

  27. Bob The Builder on April 4, 2017 at 5:30 am

    I was right with you. The entire way. Then you mentioned something anti-vacc, and immediately it made me want to just disregard everything you said. I know for a fact flea medications for pets are dangerous and most likely lethal – I will not put that crap on my pets, even though they are itchy and miserable, because I’m not cruel- but the problem is you are discrediting the entire argument against the pesticides by saying something that has no basis in reality at the end. That harms everyone, because I know a lot of people who would feel just like I did, and probably disregard everything you said based on that one statement.
    It’s rather disconcerting, the amount of evidence there is & scientific proof about vaccinations, while there is virtually no unbiased data or evidence that flea/tick meds are indeed safe, and there is a fairly immediate reaction in most cases to the medication. Everything I’ve read leads to the conclusion they are unsafe, and the fact that one of the chemicals in this Trifexis is sourced from China is the biggest red flag you could ever have. There are virtually no regulations there about anything, and even the ones that do exist, are practically never enforced. They don’t give a crap about animals, obviously. Why a company sources an ingredient from a country that makes it illegal to sell cosmetics & medicines without rigorous animal testing, to use in a medication for animals, is beyond me. The only reason that makes any sense is the company is a sham, all about profit & should be shut down immediately, because they are purposely poisoning pets for profit.
    Try to leave the anti-vaccination crap out of an article that has absolutely nothing to do with it. More people will be willing to listen & use this important information to them. We need to not focus on other things while informing them, keep it about the animals. Inserting nonsense (whether you agree it is nonsense or not) that is widely not accepted by those in the medical or scientific community, and has a clear bias, when it has no place here, is just damaging to your site, your mission, & the education you are trying to share with people.
    If you are unaware, John Mercola is a fraud, and at the forefront of the anti-vacc nonsense. Look it up. He is just profiting off of people’s fear & lives in a multi-million dollar home from it. He tells you things are terrible, but for the “low” price
    of 5x more, you can totally buy something that is much safer, directly from him! Give me a break.
    He has been told multiple times by government authorities to stop spreading propaganda & lies, particularly under the guise of being a doctor, and peddling his products. This guy is worse than any evil company selling poison, believe me. He makes you trust him with his fear-mongering nonsense, and uses it to take advantage of you! He pretends to be the alternative solution! I’ll take science-backed, rigorously tested, peer-reviewed information any day over the obvious pandering, fear-mongering, fake doctor telling me to buy his products…
    People need to use their heads, instead of letting emotions control their decisions like this. These fake doctors rely on people only depending on emotion & feeling. It’s how they make bank. Frankly it should be illegal, punishable by several years in jail. Even that wouldn’t be enough for these criminals.
    By saying that at the end, you just made it a lot harder to fight the battle against these companies poisoning our pets…. 🙁

    • M H on April 24, 2017 at 4:45 pm

      I just have to give you this link to a recent youtube video of a vet before the courts with information about vaccinations that I think you might find interesting. Thank you for your time.

      • M H on April 24, 2017 at 4:46 pm

        That comment is directed towards Bob the Builder. I apologize for not posting that properly.

  28. Kimberly on February 20, 2017 at 3:19 pm

    I am a sociologist and an owner of two dogs who are on Trifexis. The original post by the DVM is wroth with inflammatory remarks meant to induce the masses into irrational decisions. 1st he uses DOSES sold. The boxes contains 6 pills. So take his “dose” estimate and divide it by 6 which will give you a better, statistically accurate, approximation. I’ll touch on some of the bullet points that I feel are inflammatory.
    1. “failure to get rid of hook worms”…. I thought you were posting that the product is a pesticide…how does pointing out that it doesn’t kill hook worms (which are some of the easiest internal parasites to kill) advance your argument?
    2. Refusal after first dose.. Neither my Maltese or my Doberman have EVER just
    “taken” meds, I always have to do things the old way (open mouth, put pill in mouth, then hold head up rub neck, then blow in their nose and hold till they swallow.
    4. The fact that you even wrote the word “alleged” means that even you know there may or may not be any connection.
    5. “A vet”… No source? No way we can verify? This is a logical fallacy at best.
    6. Vomiting I was told by my vet the first time I bought Trifexis that they need to take it with food. The first dose I gave (immediately after eating) DID make my Maltese vomit. Now I feed the dogs, wait about 45 minutes, then give the pill. Haven’t had an issue since…..
    7-14. Can ALL be symptoms of hundreds of underlying conditions!!!!! One of the BIG ones being improper nutrition! *** People, think a minute before you by the “good” food with veggies for added nutrition… Dogs DO NOT need vegetables!! They are OBLICATE CARNIVORES!!!! In fact, since their bodies do not quite know what do with vegetables, they may activate food allergies!!!!! Food allergies, as we know, are critical, front of the mind conditions, when a human has them. Why would they not be as critical if your dog has them. There are some bad pet parents that spend the very minimum money on there dog as possible. For example, in my state, the only test a dog has to pass to get a Trifexis, is a negative heartworm panel…..Another thing is all of the line breeding done in the 60s and 70s. The Backyard breeders that continue to pollute the bloodlines of our AKC dogs. A MALTIPOO WILL NEVER BE ACCEPTED BY AKC! IN FACT, all it is, is A MUTT! Some breeds have been so wrecked that they are have malformations and underlying (silent killers) when they are born.
    The biggest problem I have seen with Trifexis is that the fleas are building an immunity to, as they do with all…”treatments”. Remember the original versions of Frontline and Advantage….
    Just to add I live in a HIGH flea area.

    • Bob The Builder on April 4, 2017 at 5:43 am

      Couldn’t have said it better myself. Seriously.

  29. Nancy Johnson on February 12, 2017 at 3:51 pm

    My dog was prescribed trifexis a week ago. He has been taking triheart with no problems but the vet insisted that trifexis is better.
    When I told the vet that my dog has health issues along with episodes of vomiting and seizures, he again reassured me that trifexis is safe but I could cut the pills in half to lessen the chance of vomiting.
    When I mentioned to my groomer of the change in medication she told me NOT to give it to my dog. She cited numerous deaths attributed to this drug and it is not recommended for breeding dogs. She has been the groomer for my little guy for over seven years and I trust her implicitly.
    We went to our vet and got Leo on triheart and he has no reaction to this medication. I contacted trifexis and they said the medication is safe and refused to even discuss the amount of money I spent on something I now refuse to give my dog.
    Not only am I disgusted with this company and their non-concern for the well-being of our fur babies, but their company line makes you wonder how many animals have been harmed by their lack of concern.

  30. Stephanie on January 27, 2017 at 10:22 am

    My puppy is 8-weeks old today. My previous Dobie, was on Trifexis. Yes, I didn’t experience any issues with his health, etc. However, I traveled to Colombia to visit my father and asked around for Trifexis. All the vets advised they did not carry this product because of the repercussions. Now, I’m curious – What should I give my baby for heartworm, fleas, and other worms? Are there any suggestions?

    • Will Falconer, DVM on January 28, 2017 at 9:00 pm

      Hey Stephanie,
      A great sign that we are a world wide community, caring about our animals!
      Here’s what’s been working for decades to keep heartworms out w/o poisoning: my Drug Free Heartworm Prevention.
      Ditto for fleas: Non-Toxic Flea Control
      Other worms have never been an issue in my patients, and I think that starts with good food.
      You’re at the cusp of a new life, so those wise decisions you make now will have long term good consequences for your new pup.

  31. Colin MacManus on January 24, 2017 at 10:09 pm

    Trifexis tablets eventually lead to the death of my perfectly healthy 96lb black labrador retriever who suffered a seizure 7 days shy of his 9th birthday and having had his last Trifexis dose 24 hours prior to his death.
    1 hour after consuming on that fateful morning, he threw up all of his breakfast and a semi-digested Trifexis tablet.
    I have video evidence time-stamped to support this.
    Trifexis kills dogs.
    Check the MSDS reports on Spinosad the active ingredient in this medication.
    it is not flattering.
    This medication should be removed immediately by the FDA from all veterinarians’ offices and clinics statewide. They do not sell this in UK or AUS or CAN. Many other countries have outright banned this stuff.

  32. Lori on December 10, 2016 at 12:09 pm

    I gave my dog Trifexis this summer twice and he got very sick so I stopped. His health deteriorated after that and I took him to the vet, who said he he so many illnesses reported and pancreatitis that he stopped carrying it! And now guess what? My dog has pancreatitis! Please do not use this medication!!! I’ve never seen such adverse effects in my many years of owning pets. The company should be held accountable for not testing this properly.

  33. Vanessa on November 10, 2016 at 11:43 am

    I concur Cody. I’ve been rescuing/adopting and treating all kinds of dogs – but mostly large and giants as they are harder to find homes for – for decades (no I shall not divulge my age hahaha) I’ve been using products such as Program and an ivermectin/pyrantel med for heart worms since 1985 (when I graduated from med school … people med, bc I love animals more!) and was able to have dogs in my own home. I’d used the same vet from ’89 until his recent death in 2015, and he was always amazed at the longevity of all of my large breeds! egs. Gr Dane lived to 13 yrs, Newfie to 14, etc. Maybe it’s luck/good karma/love I don’t know, but I have had no reactions to any flea/heartworm meds (including Trifexis) – that would be in 21 dogs. When I was in med school and the pharmaceuticals were cost prohibitive I did use garlic etc. but I did not know of a heart worm substitute.
    Now I do continue to use meds for fleas and heartworm, but I am SO sad that these kind dog lovers and owners have had such tragic events! I wish I could figure out what I am … I guess, what I’m doing right … and/or send my good fortune to you all!
    And to those people who have not experienced any untoward effects – that’s awesome! As an MD I do use medications, however if someone shows me an alternative therapy that works, I’m all ears!

  34. Heather on October 26, 2016 at 10:41 am

    Any alternatives to this medication? Natural alternatives just don’t work and other meds make her sick that is why we have her on Trifexis!

  35. Walt on October 14, 2016 at 12:05 pm

    I can only go by my experiences. Ilived in a house with multiple dogs for a while. my expire had several my daughter had several. I have a Silky terrier. For the first three years I had him,( i rescued him from a local shelter at around 4 years old) he constantly itched to the point of rubbing himself raw. going to my vet and getting “Comforttis” with no results.,every medicated shampoo as well as following an all natural protocol including vinega,r salt baths, garlic, grain free food, all to no avail. I finally moved out with my dog so I could control the fleas. His issues continued. I went to a new vet. who gave my little guy some antiboitics and steriods and “COMBOGAURD” since that treatment no more scratching no more raw skin no more sour smell from his coat. its been 4 years now and he’s still healthy and active at 11!! i don’t ever miss a dose. I think the problem is just like medications we are learning there are genitic components to a medictions worth andpossible side effects, that even in human is just starting to be understood.

  36. Rebecca on September 21, 2016 at 1:01 pm

    Tomorrow I will say goodbye to my Dane Isaac. He is a second generation Dane of mine and the last of his family, so to say that this is painful is an understatement. July of 2015 he had his yearly check up and was heartworm negative, and I made the decision to switch to Trifexis. The only side effects he had was an upset tummy with each dose, which could be negated with food. He never missed a dose. July of 2016 he had his yearly check up, and he was heartworm positive. He began immediate treatment. 3 months into treatment, he was diagnosed with a tumor in his abdomen that had caused his stomach and intestines to shift. It was also discovered at that time that his heart had tripled in size, decreasing his lung capacity to only 1/4 of what it should have been. The heart damage was caused by the worms and because of this damage, he could not tolerate surgery to remove the tumor. He is 6 years old. He makes the third dog this year in my area of Athens Georgia to contract heartworms, despite being on Trifexis. Please stop giving your dogs this medication and pray the FDA will take away their approval before more dogs and people have to suffer.

  37. Pj riley on August 9, 2016 at 9:22 am

    Ok so last year my 4 year old rottie got, hot spots bit only in the summer.. now for 2 years prior.
    All 4 of my rotties are on advantix..
    Only chevy has getton these..
    Last year , again no fleas bit hotspots.
    Course of treatment presezone. Ok all goof after summer.
    Yet i flea shampoo him as well and i see nada.
    Than in my bedroom, he is the only house dog, i get bit by a flea..
    Than i think he is allergic to the flea bitea.
    He is biting like mad. I have tried all the natural shit and it wont work.
    I use a collar to atop him chewing up his back side and legs.
    He hasnt eaten for 2 days and looks miserable
    Finally i went and asked for a good flea med .
    They gave me this stuff.
    One day after he ate a little bit still scratching and bitting a bit day 2 he is eating and slightly nibbling.. day 3 he is eating on hi regular routine and is his happy self again.. so far so good. We are at day 4.
    I know all my rotties as i have bred them for years..this is my first with a dog sooo alergic to flea bitea.. drastic meds have been used.. lets see how this holds up

    • Joe on August 27, 2016 at 2:03 pm

      Give your dog Trifexis!
      Yes, it is expensive. Yes, it is chemical. Yes, it might harm your dog (is a very, very small percentage of the cases).
      Or … you can give your dog a few spoons of Guinness beer a month – it must be the one made is Ireland! Lol.
      There are people who believe pumpkin seeds can cure cancer. And there are people who believe pray can save lives. This is called “mysticism”. There is no proof of it, just faith.
      I won’t hold you right or wrong any way you choose to go. Just different.
      A few decades ago, when dogs were not used for companion as they are today, they had a much better life. They would die more often, true. But they had more freedom as well.
      One fact is immutable: your dog will eventually die. This is inevitable. And when he/she is gone, an empty hole will be formed in your heart. There is nothing to heal this.
      Good luck in your endeavors!

  38. Ivanise on July 27, 2016 at 7:38 pm

    I am from United State Of America, I was diagnosed of chronic pancreatitis in 2005 and I have tried all possible means to get cured but all to no avail, until i saw a post in a health forum about a herbal doctor from Africa who prepare herbal medicine to cure all kind of diseases including pancreatitis, at first i doubted if it was real but decided to give it a try, when i contacted this herbal doctor via his email, he prepared the herbal medicine and sent it to me via courier service, when i received this herbal medicine, he gave me step by instructions on how to apply it, when i applied it as instructed, i was totally cured of this deadly disease within 16 days, I am now free from the deadly disease, my digestive system is now working perfectly, i no longer feel all the horrible pains. Contact this great herbal doctor via his email drlusandaherbal(AT)gmail(DOT)com or his website on www(DOT)drlusandaherbal(DOT)weebly(DOT)com

    • Joy on February 11, 2019 at 5:57 pm


  39. Rosie on June 24, 2016 at 6:50 pm

    I just got my Schnoodle Chihuahua a couple weeks ago, and I just brought him into the vet the other day where the vet gave me a free first dose of Trifexis to give him. I haven’t given it to him yet and after everything that I’ve seen online I don’t think I will. There’s got to be a safer way to protect my dog from heart worm than putting poisons into his little 5 pound body.

    • Will Falconer, DVM on June 24, 2016 at 9:34 pm

      Oh, good catch, Rosie. I’m so glad you found your way to a thoughtful decision. I can’t tell you how many just give the pesticide, never thinking.
      “It’s free? Dr.WhiteCoat gave it to me? Great!”
      You evaluated first. Decided poisons were not the way you wanted to treat a loved one. Bravo!

  40. leona firewolf on June 9, 2016 at 5:56 pm

    OMG! I give Trifexis to my 2 dogs, I haven’t give them their pills this months yet, and after reading this I’m not giving it anymore! ( they been on it a year) no problems yet but don’t want to to take a chance with it! my vet put them on it because of round worm’s we have them in the ground where I live at and they almost killed my Akita, now to find something for the worms & flea’s thank you

  41. Rich on June 4, 2016 at 2:56 pm

    I just started my 4 year old Soft coated wheaten terrier on Trifexis 6 months ago and he started having these nervous ticks as described above. Immediately after I gave him his last 6 month pill, he started vomiting all over the house. Then for no apparent reason, the nervous ticks started. He was running all over the house like a mad dog. He would jump up from a deep sleep three feet in the air and take off running. I called the Elanco Company to report it and told them I had a vet appointment the same day. Elanco called my Vet three times to get a report. If their products are so safe, why should they be at all concerned? Why do the Vets protect them and do not inform the customer about these serious drug interactions?

  42. RVT with boxers on May 7, 2016 at 10:17 pm

    In 2009 I adopted a 7 year old, heart worm positive boxer with a broken hip from my local SPCA after seeing him on the euthanasia list for the day. At the time I worked at a speciality veterinary hospital and King was referred to radiology for radiographs, an echo, and then to internal medicine for complete labs and a fecal for his reported diarrhea (the SPCA’s listed cause for his euthanasia). Aside from being about 35# underweight, slight changes in his heart secondary to heart worm infection and his shattered hip, everything was normal. The internal medicine specialist had me give him heartgard for 2 months, he was checked for microfilaria, and when negative, started on Trifexis and doxycycline as treatment. Within 3 months he would have episodes of vomiting (bile and undigested food), and intermittent diarrhea despite a grain free hypoallergenic diet his acupuncturist designed. Lab work at 6 months and repeat echo showed King had elevated ALT levels (twice normal), was only a light heartworm positive, and had a drastically decreased worm burden. At 9 months he had protein in his urine, ALP was elevated, and he was heartworm negative. At a year, the vomiting was so frequent, and a repeat echo revealed no heartworms, while an abdominal ultrasound showed a slightly enlarged liver, so the Trifexis was stopped and he was started back on heartgard. He had regular lab work every 6 months, and volunteered to teach several local vets how to perform ultrasounds, and after 3 months off Trifexis his ALP was normal and ALT was decreased. His vomiting drastically decreased. At 6 months, all of his lab values were normal and his liver size returned to pre-Trifexis size. Up until his passing at 14 from a mediastinal mass and hypercalcemia, his liver values never tested abnormally again and he never had Trifexis again. My other boxer was tried on Trifexis and had sever hypersensitivity. Sentinel caused hives, facial and limb swelling, and now after she developed cancer, even ivermectin causes neurological issues (high stepping, bumping into things, saw horse stance). I’ve seen countless patients in the clinic on Trifexis with elevated liver values, and you have to wonder how toxic this medication is that it insults the liver and damages it enough to raise the values? And even more reports of vomiting come in. When clients ask me how I feel about a medication causing vomiting, I can’t help but tell them it sounds like it’s time to find something safer for their pet that doesn’t cause negative symptoms. I’m curious and worried to see how all the new flea products like Bravecto and Activyl are going to affect animals. I’m too scared to give something like Bravecto or Proheart that stay in the system for months. Kudos to all the pet parents brave enough to speak up and tell their vets that they won’t be giving medications with damaging side effects to their fur babies.

    • Will Falconer, DVM on May 9, 2016 at 9:18 am

      RVT, thanks so much for this insider look at the damage that was done by this drug. Amazing the follow up you did and the conclusions you’ve fairly drawn. The liver, as you intimate, can take a lot of abuse before the enzyme levels start to elevate or the organ itself starts to swell. This is a great story of intoxication at the hands of a drug purportedly marketed to help prevent disease.

  43. Kay beebe on May 5, 2016 at 8:56 pm

    Our12 year old Westie had his second dose of Trifexis one week ago. The last five days he has been lethargic and sleeps a lot. Not at all like him. The vet discovered an irregular heart beat, something he did not have in March of this year. Had EKG and also blood work. Blood tests are all perfect.
    Is there an antidote you would recommend for the Trifexis? I have read some things on the internet regarding liquid dandelion and milk thistle for a detox. Any thoughts?
    Thank you in advance.

    • Will Falconer, DVM on May 9, 2016 at 9:23 am

      Hi Kay,
      You’re asking a homeopath, so I like a common detox remedy called nux vomica 30C. You can buy that anywhere remedies are sold, and I’ll be putting up a protocol on my latest Apoquel post very soon, so check there on how to dose it.
      The herbs are fine, don’t get me wrong. If someone has a protocol that’s got good legs (demonstrated effectiveness multiple times w/o harm), that’s a fine place to start.
      Your 12 year old is talking to you. I hope you’ll not give another dose, learning what you’ve just learned.

  44. Martha Burrows on May 5, 2016 at 12:24 am

    I do not believe the post-approval adverse reactions for Trifexis cited on package inserts are credible based on the following: On the abbreviated Trifexis package inserts printed in the JAVMA magazine, Vol 244, No. 4, February 15, 2014, and in the Veterinary Medicine| magazine, May 2013, it states the following: “Post-Approval Experience (March 2012):”. (i.e. implying that the post-approval adverse reactions are based on data up to/including March 2012) The production date at the bottom of these same Trifexis package inserts is
    “(V02-06-2012)”. According to numerous pre-press proofs from Matthews Brand Solutions, an art production studio that works for Eli Lilly/Elanco, “(V02-06-2012)” is their “Text Approval Code” for final artwork to be printed. This indicates the text on these Trifexis package inserts was written and approved by February 6, 2012, which is BEFORE March 2012. I wonder if this means the rest of the data cited on these package inserts could also be a work of fiction?

    • Will Falconer, DVM on May 5, 2016 at 1:38 pm

      Hey Martha,
      More significant to me is the length of time the drug has been getting used, and the growing body of side effects that real people with real dogs are reporting. Is that double blind studies? No.
      But are deaths and serious sicknesses after a drug entered the bodies of many companion animals over several years real? I hold strongly that they are. The more who come forth with reports like these, the louder becomes the denial or, worse yet, the silence from Elanco

      • Martha Burrows on May 5, 2016 at 6:19 pm

        Here’s another interesting fact. On August 8, 2014, Eli Lilly registered the domain name “TRIFEXIS-DEATHS.COM”. One has to wonder why? The site is no longer up, but I wonder if it was used as a means to divert, capture and dispose of negative Trifexis comments during that peak death period. I agree with your long-term effects POV. My perfectly healthy dog took Trifexis for four consecutive months with no negative effects. He didn’t even vomit. Then he became acutely ill and almost died. He pulled through though and for six months appeared to have made a full recovery. Then one day the same effects came back and he suffered a horrific death.

        • Will Falconer, DVM on May 5, 2016 at 6:26 pm

          OMG! You’re hired, detective Burrows! That’s pretty chilling, isn’t it?
          As was your experience with the delayed effect that seems quite common with this drug. It seems as though the stronger dogs can withstand it for some time and then go down. Some for years, perhaps like my Mom who smoked all her adult life and finally died after the hospital techs tried to help her breath by suctioning out gobs of black tar.
          My condolences for your loss. That’s got to be so hard to look back at, I can only imagine.

  45. Michael Gordon on April 18, 2016 at 10:36 am

    *Repost from March 22, since I didn’t get a reply to my original message*
    I never realized Trifexis could be so dangerous, but now it makes more sense. We lost our Gunny, a beautiful Red Bone Coon Hound/Lab mix almost a year ago exactly. He was only four and a half. He began having seizures about a year or so before he died, not long after we started Trifexis. My concern now is for our Lily, Bowie, and Phoebe. Lily is almost two and has had at least a year’s worth of Trifexis. The other two are pups and have had only one dose. How do we know if Lily has been harmed by it. She and the pups (not her pups) do not show any adverse reactions. How can we tell if damage has been done? Please respond.

    • Will Falconer, DVM on May 4, 2016 at 10:25 am

      Hey Michael,
      You’re asking a homeopathic vet, so I have an answer from my place on the practice path: you’d be seeing symptoms if illness was present. That links points out common chronic disease symptoms that most people aren’t aware of. We look deeper, and have a different definition of “normal” and “healthy.”
      You could also run some blood work, a CBC and Chem Screen, and see if all is within normal limits. Your local vet can do this easily.
      All the best and my condolences for your losing Gunny.

  46. Lovinnia Gotao on April 3, 2016 at 11:33 pm

    My dog was given trifexis as a puppy and was okay with it in the beginning. But when we increased dose, he would be so lethargic and drugged. Throwing up, diahrea. I took him to the vet everytime. And they said it couldn’t be the trifexis. I changed vet and they switched him to another brand, I forget the name now. And he hasn’t been sick anymore.

  47. ZumaDog on March 29, 2016 at 3:11 pm

    Well… I’ll jump in since I see your comments section is still actively flowing nearly 2 years after your post.
    My family just brought home pup. We haven’t owned a dog before, so a lot of this is new for us. We selected a vet. Seems good enough. They do the normal exam, tell us we have a good dog, etc etc.. (he’s a thriving energetic puppy, of course he’s good…)
    We are getting his boosters for parvo, just got his rabies vaccine. I’m okay with all this.
    On the 2nd visit the doc offered a free Trifexis booster. Told us not to give it for a couple days because he just had his booster and it may make him sick if its too close together. 2 things, first, I’m lazy and forgot to give it to him, second, I believe in not giving my pets anything I wouldn’t take… and upon further inspection, wow, would I not take this.
    So here I am about a month later, just had a follow up visit. The vet asks if I want to get my next month of Trifexis from them… (in my head I’m thinking, oops, do I tell them I forgot), then I ask, how much… $25. $25, wow! My follow up question, naturally, how often do I have to give this to my dog…. well, every month for the rest of his life sir. I laughed, then I got motivated to figure out what this was all about.
    Naturally google searches led me here, and I’m glad it did. I just threw out the free sample I was given and I’ll be exploring more organic methods of raising a healthy dog.
    Btw… the thought crosses my mind as I read all this. How did dogs survive without heartworm or flea medicines in the wild? (meant to be a sarcastic rhetorical question…)
    If you couldn’t tell by now, this is just a thank you comment. To you and to all the folks who shared their stories. Nothing like first hand accounts to help sift through what the manufacturers wont share.

    • Will Falconer, DVM on March 29, 2016 at 3:34 pm

      Thanks for stopping by. I’m glad you’ve found value in this to help you make sound decisions for your new bundle of energy.
      All the best going forward. It’s a great time to set the stage for a healthy, long life!

  48. William on March 29, 2016 at 12:35 pm

    Hello Doctor & Everyone!
    What about not treating for heart worm or parasites and just paying for a comprehensive lab test every 6 months?
    I am located in southern California, a relatively low-occurrence heart worm area.
    Is it true by doing this we could not only avoid using drugs, but if heart worm is actually detected, within the six month time-frame the worms would be very small and easily treatable?
    Interested in your thoughts as this might be a viable option for many owners.
    Thanks from San Diego!

  49. Michael Gordon on March 22, 2016 at 9:11 am

    I never realized Trifexis could be so dangerous, but now it makes more sense. We lost our Gunny, a beautiful Red Bone Coon Hound/Lab mix almost a year ago exactly. He was only four and a half. He began having seizures about a year or so before he died, not long after we started Trifexis. My concern now is for our Lily, Bowie, and Phoebe. Lily is almost two and has had at least a year’s worth of Trifexis. The other two are pups and have had only one dose. How do we know if Lily has been harmed by it. She and the pups (not her pups) do not show any adverse reactions. How can we tell if damage has been done? Please respond.

  50. john on March 17, 2016 at 8:57 pm

    you want to detect bs, start at the top of this article and dont stop until reach the bottom. I raise dogs, all my family have dogs, we started with comfortis and now use trifexis because it works wonders. No side effects, no fleas, no ticks, no worms. Are there certain dogs that will have a problem with it …yes…….JUST LIKE EVERY OTHER MEDICINE……10s of millions of doses and 700 documented deaths, thats safer than asperin. And thats just dogs, the active ingredient is used for many other animals. If your dog dont tolerate it well, dont give it to them……but dont denigrate a wonderful product because of your all natural prdjuduces……thanks for my chance to rant…….john

    • Shea on March 18, 2016 at 10:07 am

      I have been giving this to my small mixed terrier for years with no I’ll effects. With everything I’m reading about it being poison, I wanted to switch her off of it to heart gard and some other flea med. I was giving comfortis for a long time but it seems it gets reviews just as bad as trifexis. I’m seeing mostly bad reviews and it was good to see someone who’s dogs do okay with it. Still confused what to do. I gave her the last dose in the box this morning with her breakfast and she has been running around and playing. She is 8 years old too!

  51. Martha Burrows on March 16, 2016 at 11:13 am

    Yes, my first assumption was the same. However, there are three factors that led me to think more optimistically. For one, if she were a diverter, it would be very easy to track her down through the lot #s etc.. Secondly, she appears to have been the lead vet tech at the Humane Society in Memphis and volunteered at free spay clinics. And thirdly, she appears to now be involved with a German Shepherd rescue initiative in another state. My mission is truth. I have no interest in profiting from my dog’s death.

  52. Martha Burrows on March 12, 2016 at 4:27 pm

    I lost my beautiful Samoyed dog in June 2013 here in Canada after being prescribed Trifexis, and have been on a mission ever since.
    I just found the following document from the Nashville, TN veterinary board dated December 2014. Here is the link:

    Here is the relevant excerpt:
    “Consent Order – Amy Keller, L.V.T.
    Ms. Keller was not present and was not represented by counsel. Mr. Keith Hodges, Assistant General Counsel, presented the Consent Order to the Board for ratification. Ms. Keller stole Trifexis worth over fifteen thousand dollars ($15,000.00) from her employer. She pled guilty to Theft of Property worth between $10,000 and $60,000, a Class C felony, in Shelby County Criminal Court. Ms. Keller agreed to voluntarily surrender her license to practice as a veterinary technician and to pay costs of the proceedings. Dr. Galloway made a motion, seconded by Dr. Federico, to accept the Consent Order. The motion carried.”
    One has to wonder why a vet tech would risk her career and a criminal record to steal $15,000.00 worth of Trifexis from her employer unless she was trying to make a point and save some dogs’ lives, perhaps based on what she saw on the job? Hopefully that is the case.
    Also, Trifexis was launched in the U.S. two weeks after Assurity for cats in January 2011. (both Elanco products) Assurity contained spinetoram pesticide and was also blamed for cat injuries, illnesses and deaths. U.S. EPA labels for Assurity indicate that it (and now Cheristin for Cats) was/is commercially manufactured in Canada. I wonder is Trifexis is as well?

    • Will Falconer, DVM on March 16, 2016 at 7:02 am

      Hi Martha,
      I’m gonna take a swing and guess this theft was motivated not to save lives in some way, but to profit from sales on the side.
      An older professor in vet school once told us, “If you’re in No. America, and hear hoof beats behind you in the field, you’d better turn around expecting to see a horse, not a zebra.” In other words, the most obvious thing should be the first on your mind, not the rare and unusual.
      I’m sorry you lost your Sammy after starting Trifexis. And I wish you all success in your mission, if it’s one intent on educating.
      Thanks for stopping by.

  53. John on March 3, 2016 at 5:12 pm

    Original article is completely one sided with no scientific basis or facts, just testimony and heresay, which is NOT scientific research. 700 dogs from 70 million doses = 0.00001%, which is probably about the percentage of dogs that have undiagnosed serious conditions, such as brain tumors or leukemia. Yes the flea treatment probably puts an initial strain on the dogs immune system which could cause these conditions to now become apparent. Because the timing coincides with the administration of the flea treatment, the conclusion is that the flea treatment is the cause, which may not necessarily be the case.

    • Cody on March 16, 2016 at 1:04 am

      I agree…. I’ve posted several responses here pointing out the same thing. There are plenty of medications people take that can have rare but serious side effects. That doesn’t mean they are pulled from the market so we can suffer with the issue the medicine would have addressed.
      We have a Shiba Inu that’s been on Trifexis for years. My dog is healthy and parasite free. We have friends with two Shiba Inu’s, both take Trifexis, both are healthy and parasite free.
      The sad thing is no one ever posts when the drug is working great. They only post horror stories when something goes wrong. That’s human nature. Few people go online to share good reviews. Most only post a review when they have something bad to say. So all you see online are the 0.00001%.

  54. Lisa on February 27, 2016 at 9:00 am

    I was willing to read but you lost me “vaccine-induced autism.”

    • Will Falconer, DVM on February 28, 2016 at 5:56 pm

      Still waiting for the double blind studies, Lisa? Talk to some moms who had normal children until a certain MMR or DPT ruined their lives. No one in that situation needs to be told it wasn’t real until the studies come out.

      • Cody on March 18, 2016 at 4:12 pm

        Society would still be battling Polio, Hib disease, Whopping Cough, Measles, Tuberculosis, Smallpox, Tetanus and Rabies if it weren’t for vaccines. Some of those diseases have been outright destroyed completely by vaccines.
        The people of today are spoiled. They didn’t have to witness people slowly dying in iron lungs.

        • Will Falconer, DVM on May 4, 2016 at 10:28 am

          Pure BS, Cody, and I’m sorry you’ve bought it. It’s quite easy to find the graphs of disease declines, 85% of the decline in incidence coming long before the vaccine ever hit the market.
          It’s not that people are born “broken” in some way, and only a vaccine will make them whole. C’mon, in your heart you likely know this.

          • chad on August 6, 2020 at 1:30 pm

            Dude, …the anti-vaxxer myth has been thoroughly debunked. Pesticides for sure might be bad, but there is no link to autism and vaccination.

          • Will Falconer, DVM on August 9, 2020 at 10:00 am

            Seriously, you drank that Kool Aid? I’d like you to stand tall and tell the mothers, one at a time, that their perfectly normal, well developing child whose world fell apart after a vaccination, that the vaccine had nothing what so ever to do with it. Report back when you’ve done that with ten moms, whose lives will now revolve around their broken child, who’ll be in diapers as a twenty-something dependent. We’ll wait for you.

        • julia on May 16, 2016 at 1:02 am

          Cody– as long as the USG and other nations continue modifying & ‘improving’ ALL the diseases you’ve cavalerly listed – there is no such thing as eradication of any percentage you may choose to cite.
          They are routinely re-released on unsuspecting populations globally & you know this.
          The more you nay-say Dr. Falconer’s reporting – the brighter his light shines on the reprehensible practices of the drug/pharma industries – and those who are paid to support it.
          Vital Animals is not the only site with such
          excellent, healthful information – we who know alternative modalities work best will always persist in application of them.
          Whatever negative effect you’re attempting here – won’t gain traction.

    • Bob The Builder on April 4, 2017 at 5:53 am

      Me too. Saying people coming here don’t agree is just ignorant. It’s the internet. People will obviously come across the page during a search. Obviously this guy just doesn’t like argument because he has no proof to back his claims up.

  55. Asop on February 18, 2016 at 1:54 am

    Well, I just bought trifexis form my Vet in Israel.
    The Flees which nothing could get rid of are gone! no apparent side effects and my dog seem to be happy as ever just without scratching herself. also my parents dog is fine.
    Both dogs weight about 20 kg and of the Canaanite breed (Mix)
    My vet did tell me you cant give the pill with the Worm treatment which i have to give my dogs every three months.. could be the problem who caused all the incidents mentioned in your article.
    The pill can only be given by the vet which makes it a bit more expensive, but the dogs are being kept under the care of the vet.

    • Phoebe on July 13, 2017 at 12:14 am

      Mine wasn’t on worm treatment pill when he got sick from taking Trifexis for 4 months

  56. annamarie giordano on February 17, 2016 at 1:32 pm

    I lost my perfectly healthy 11 yr old Airedale terrier Nov.14th. She had symptoms of eating something that inflamed her intestines. After month of a bland diet she slept all the time.took to local animal hospital treated for inflamed intestines and possible pnemonia. she was very anemic , refused to eat or drink. vets monitored blood 4 days in row blood count never changed. didn’t want to walk and looked up at sky and leaned both to left and right. hospital recommended she see internist drove 4 hours to see one. sonigram came back fine told us to check back in a week. drove 4 hours home and she passed away when we backed into driveway. she had been on Trifexis for at least 3 years

  57. Sher Coats on December 28, 2015 at 6:09 pm

    Within a week of Waggles annual exam and the vet recommending a switch to Trifexis, my little guy had blisters on his face, nose, lips, around his eyes. He was given a shot of steroids (didn’t help.) A biopsy was done, no problems. His bloodwork came back with his liver enzymes at 3600 (normal is 100.) His organs, including skin, began to turn to mush. He went blind, his toenails dissolved, his penis literally fell off!!! His anus was oozing. I called (got an answering machine), e-mailed and none of my requests for an anecdote were answered. His hearing was going. I had to end his suffering and the ONLY thing I did different was POISON him with Trifexis!!! I’ll never believe it wasn’t anything but that poison Elanco is passing off… make a quick multi-million, then pull it off the shelves when they are forced to. My baby died from Trifexis. I have the pictures to prove his disintegration from the day before he took it to the week I had to force myself to end the misery and suffering.

    • Will Falconer, DVM on December 28, 2015 at 6:33 pm

      Oh, Sher, I’m so sorry you had to suffer this with Waggles. I can only hope you’ve gained a deeper understanding of conventional medicine/pharma and a renewed determination to make changes going forward. Nothing can replace him, of course, but if his suffering and death has in any way inspired you to walk a more natural path, he will not have died in vain.
      All the best to you in healing what must be a huge hole in your heart.

  58. cynthia oxley on December 19, 2015 at 12:59 pm

    I adopted my little buddy in 2012, mix breed. I had him for 3 months before my vet put him on trifexis. He did not have any seziures during ther first 3 months i had him. 2 months after starting this med. he started to have seziures. The vet could find no reason for them and said to keep an eye on him. He has seziures now minimum of once a month! I regreat ever putting him on this stuff!

    • Will Falconer, DVM on December 19, 2015 at 1:25 pm

      Hi Cynthia,
      I hope you’ve stopped giving it. Far better alternatives if you search around my site.
      Best to you both.

  59. SUSAN NOVAK on December 16, 2015 at 8:32 pm

    Recently lost our dog 3 days after taking trifexsis and vomiting, becoming dehydrated and showing a very high creatin level. She was fine before this and has taken trifexsis before. What i’m trying to find out is what happens inside dog’s metabolism when this pesticide is working. ?? What pharmacological action happens?? What organs are taxed when metabolizing this?? I have recently put up another petition to the FDA on for what it’s worth just to keep the issue in the public eye and I need to be more informed. What is the relationship between trifexsis causing pancreatitis because that is what the vet said she all of a sudden had??

    • Will Falconer, DVM on December 17, 2015 at 5:29 am

      Hi Susan,
      I’m so sorry you’ve lost your dog to this deadly pesticide combo.
      I’m not sure anyone knows what you’re asking about, pharmacologically or physiologically. I tend to be much simpler in my thinking: poisons are risky to all ingesting them.
      Thanks for getting the word out on this.

  60. LINDA on December 16, 2015 at 2:53 pm

    We have a 3 year old lab mix that has suddenly begun to have seizures. We got him from a lab rescue when he was about 1 1/2 years old. He was vet checked & has had a clean bill of health. He had his annual checkup in April. All was good. He has been on Trifexis for a little over a year & has not presented any abnormal symptoms until a couple of months ago when he began to have seizures. We took him to his vet & had blood tests run to check for any abnormalities (i.e., cancer, brain tumor, etc.). Nothing, blood work was great. Now he is having cluster seizures (2 about 15 min apart) every 9-10 days. Doctor has summized that it is epilepsy & has prescribed phenobarbital. We are not convinced that it is epilepsy & have severe reservations about dosing him with phenobarbital. Could the Trifexis possibly build up in his system & cause the seizures now? He is due to start on a new round of Trifexis but his vet has said that he is now recommending 2 other medications in place of the Trifexis, which makes me wonder if they have reservations about the drug themselves & just won’t tell us. We are wondering if the seizures will subside, if we do nothing, or will they increase. Thankfully, the seizures only last about 15-20 seconds but take about an hour to fully recover (back to normal). Above all, our dogs health matters & if the only solution is the phenobarbital, then that’s what we will do but until someone can prove to me otherwise, I would rather not start him on the drugs. Any suggestions/advice would be appreciated. Thanks.

    • Will Falconer, DVM on December 16, 2015 at 3:12 pm

      Hi Linda,
      I’m sorry to hear your lab is having seizures. That’s deep seated, serious illness (vs. itchy skin, like the dog I just had in my last appointment).
      It’s possible Trifexis had a role in this, sure. If you read the reports, convulsions are a common side effect. We’ll also see this in relation to vaccinations, however. So, it could be either or both. Needless to say, more (though different) pesticides and future vaccines are not in this guy’s best interest. I’d avoid them like the plague, for the rest of his life. He’s now got an automatic waiver, anyway: he’s seriously ill. (Search on that word and vaccinations in this site for more understanding of why I say these things).
      Blood tests are normal, 99% of the time, so no news there.
      Phenobarbital cannot cure this. It just “dumbs down” the nervous system. If you are after a cure, I know of nothing better than professionally prescribed homeopathy to get him there.
      See my Resources page for the AVH list, and see who might help you with that. Look for a vet who does mostly or only homeopathy, and don’t worry if you need to work by telephone with someone to get the job done.
      Best of health to you all. I hope this will be a springboard for change for you and your animals going forward.

  61. rey suarez on November 20, 2015 at 3:42 pm

    Thank you very much. Five minutes ago I was ready to pay about $100 on a website, but something stopped me. I am glad I found this website with your article, I was searching the web for good prices for Trifexis. I am too lucky because I have been treating my 1 1/2 years old lab for several months, following my ex vet doctor advice who never mention a word about side effects or the risk of causing harm on my dogs. Also, I have been using Brand Frontline Plus (Known as Frontline Combo) on my 5 years old mini schnauzer all these years, and now I have questions and will appreciate highly any advice. Should I stop using Frontline as well? Are there other options? Blessings

  62. Kenneth on October 27, 2015 at 2:40 pm

    Hm. I guess I’m the only one who had positive experiences. Nice weather hear round where I live and trifexis is the only medication ive used that actually helped. Tried a few other methods like vegetable oil or apple cider vinegar or vitamin e oil – they eased some mite symptoms mildly, but were no solution.
    One trifexis dose on each of my dogs regularly as instructed by my vet has worked wonders with no adverse effects. Just my .02

  63. edwin hubbard on October 27, 2015 at 11:46 am

    I have tried unsuccessfully to join and to purchase via credit card, Vital Animals Don’t Get Heartworms. Neither activate button engages. What gives?

  64. Cindy on October 19, 2015 at 5:17 pm

    My cat developed hemangiosarcoma of the spleen & had a splenectomy due to bursting of the tumor 6 months after his first dose of Comfortis. It is 3 months later & he died this past Saturday. It had metastasized to his liver. The people who make this stuff & market it as safe are monsters. I will never get the sounds of his pitiful cries while he died those final hours out of my head.

    • Will Falconer, DVM on October 19, 2015 at 5:28 pm

      Oh, Cindy, I’m so sorry for your loss. Cancer is tough enough to deal with, but when death comes amid crying and discomfort, it’s truly a heartache.
      I wish you well in this very difficult time.

  65. andy on October 18, 2015 at 1:09 am

    I’ve been medicating with Rick Simpson oil for many years, it has brought me from 50+ seizures a week to almost none. I owe my life to it. more information on cannabis oil, cure for cancer.

    • Bob The Builder on April 4, 2017 at 5:36 am

      You should be ashamed of yourself. Troll.

      • Rowena on January 10, 2018 at 1:57 pm

        Actually Bob, cannabis is proven to be worth it’s weight in gold for all sorts of medical issues…both in humans as well as in animals. Do your research before calling someone who has proven for himself the value of using it in their life a Troll. I mean really, you might as well call the Author of this blog a troll too then…because he recommends alternatives that go completely against most Vets in practice today.

  66. LilBit Ballard on August 20, 2015 at 11:15 pm

    Thank you for all the amazing facts. I am SO glad I read this before purchasing another 6 doses for my fur kid! But BIG QUESTION now: What should I give my dog to protect him from fleas, worms and such?????

  67. Jeanne Fisher on August 13, 2015 at 11:09 pm

    I started our dogs, both Dachshunds, on Trifexis in May 2015. In July 2015 one dog developed serious dermatological issues. However more alarming our other dog developed a very high fever and lethargy. We took her to the emergency vet and after blood tests they discovered she has no platelets and hardly any white cells. After many tests and procedures the vet determined she also was not producing red blood cells either. This was followed by a bone marrow test and those are being reviewed by specialists now. They have ruled out bone marrow cancer; however, what she’s left with can eventually lead to leukemia. What is interesting to me is one of the first things that the vet asked is if she had had Parvo or any tick bites as the symptoms mirrored that. I may be way off base but I keep thinking of starting Trifexis in May 2015 and our dog got very sick in July 2015. I keep asking myself – could they be related? I have searched websites to see if anyone else’s animals have the same symptoms or have developed blood cell production disease and haven’t located any. I know I’m not explaining what happened to her very well. I’d really appreciate any input. Thank you very much.

    • Will Falconer, DVM on August 14, 2015 at 5:04 am

      Hi Jeanne,
      I’m so sorry you’re dealing with this in your Dachsies. The second one has one of the most feared outcomes in veterinary medicine: autoimmune thrombocytopenia and autoimmune hemolytic anemia.
      The correlation with heartworm pesticides and/or vaccinations is the handwriting on the wall. I’ve written about the first one here on my Drug Free Heartworm page, and the second here, on my Vaccinations: Safety page.
      Conventional medicine loses about 50% of these autoimmune cases, even after heroic and expensive measures are taken. If you want to get to cure, I’d strongly suggest hiring a veterinary homeopath to guide you.
      The drugs are aimed at shutting down the immune system, which, as you might imagine, is fool’s play. Homeopathy aims to stimulate a “fight” in the patient, to throw off his disease.
      Look for the AVH list on my Resources page, and don’t be afraid to work by telephone if there’s not a good vet homeopath near you.
      I sincerely wish you the best with this very big challenge before you.

      • Jeanne Fisher on August 14, 2015 at 3:51 pm

        Do you feel there is a connection between Trifexis and her immune issues? Thanks so very much for the reply. I will definitely follow your suggestions. I’m familiar with homeopathy and hadn’t connected the dots between that and my doggie. I so appreciate your feedback and valued advice.

  68. Garry on August 1, 2015 at 4:52 pm

    The drug company can shove their bought desired reports. Every time within hours of giving my dog Trifexis he gets lethargic, starring up at the ceiling, loss of appetite, and looks totally ill. I am so afraid he could die from the next pill that I decided to quit giving him this dangerous drug.
    I basically put him on Trifexis because the fleas were biting him really bad and nothing I was doing stopped the fleas. He doesn’t have fleas or ticks now but he sure acts like he could die after taking the pill. I don’t want this dang drug killing my dog. No doubt with hundreds or even thousands of reports from dog owners being ignored shows money profits speaks louder than a dead dog. WOOF!

    • Will Falconer, DVM on August 1, 2015 at 5:01 pm

      Garry, this is a great first step to getting your guy really healthy. Bravo. If you want a vision of possibilities, see a post I recently put up on natural resistance. No fleas, no drugs, that’s what happens in really healthy dogs!
      There are a number of steps to get to that Vital place, but none are impossible, and they are outlined in that post. Hang around a while, bookmark this site and stop back regularly. The Start Here page is another way to get further info.
      Really, really glad you’ve seen first hand the response to the poison and have made a firm decision to stop using it.
      Carry on. Your dog will thank you many times over.

    • Phoebe on July 13, 2017 at 12:22 am

      Mine had the same symptoms as yours after being on Trifexis for 4 months: lethargic, loss of appetite, no interest in playing or moving. My happy active 8 months old puppy just laid in a heap for almost 4 days and was a sack of bones. Thankfully, he came around on the 4th day. Never touched that stuff or any chemical pesticide (topical or oral) since then

  69. Stacy on July 15, 2015 at 11:03 am

    Interesting article. I’ve been giving my dogs trifexus for almost a year and fortunately have had zero issues. However, this is still extremely concerning to me and I want to switch to something else now. I just wish this article offered some safe alternative options to give our animals. Any suggestions?

    • Will Falconer, DVM on July 15, 2015 at 6:11 pm

      Hi Stacy,
      It’s good to have concerns, as it seems the dogs on this pesticide can have problems at various points along the span of taking it.
      My own drug free protocol is what most of my patients use. That’s found by clicking the book cover in the upper right part of this page: Vital Animals Don’t Get Heartworms!
      All the best with making the switch.

    • Whitney on December 1, 2015 at 11:02 pm

      Hi Stacy …
      Just to let you know that my dog, who is a year and 7 months this week, was on Trifexis since she was 4 months old without any discernible issue. This past September, she had what I now know was a small seizure … head /throat/ear spasms … in the middle of the night. We called the emergency vet but didn’t ends up going as whatever it was, speed and she went back to sleep. We emailed our regular vet that night and spoke to get the next day but she wasn’t concerned as our was an isolated, and mild, incident. This past Friday night (right after Thanksgiving), she had another incident but much more symptomatic of a seizure. I was scared to death and we were in a hotel out of town. We went to the emergency vet who didn’t say much of anything but gave us an article on seizures and tremors, and recommended we see a neurologist as soon as we get home. I had given her Trifexis at 8:15pm right after dinner, and the seizure was at 5:00am. It wasn’t until we got home last night (Monday) that my other half remembered we had emailed the vet after the first incident, and to our amazement, it was ALSO ON A NIGHT WE HAD GIVE HER TRIFEXIS AFTER DINNER. I was so relieved to have found the connection and be able to tell the neurologist this morning at our appt. Though she was very reluctant to commit to the correlation between Trifexis and the seizures (kinda odd, as it’s not a regular vet but a specialist practice, so they don’t sell it there), she did advise we stop the Trifexis after our dog passed her neuro exam with flying colors. Also, not to put her on Comfortis or another that I can’t recall right now. I think we’re going to go the Heartguard route but would love advice in that area.
      Anyway, I’m replying to your post bec tippy mentioned that you hadn’t seen any effects in a year of your dog being on it, and NEITHER DID WE! I am sick that I was unknowingly poisoning my baby girl, sick that this med is still being prescribed, and concerned that some (most?) vets aren’t doing their due diligence and researching what they recommend. It unfortunately only takes a quick Google search to see what’s happening! I do realize that ultimately, it’s in me to research what I give my pet but why wouldn’t we all trust our vets whom, at least in my case, we chose after MUCH research and bad experiences elsewhere.
      I’m calling my vet first thing tomorrow and telling our story. This whole situation has me channeling Erin Brokovich!
      Good Luck to you!

      • Will Falconer, DVM on December 6, 2015 at 4:38 pm

        Great catch, Whitney. I’m so glad you’ve reported this. It took OVER A YEAR of dosing, without apparent illness, until seizures hit, folks! Be aware: pesticides are not friendly to living organisms, and a little bit of poison monthly will eventually bite your dog, potentially fatally.
        Love to hear what your vet’s response was, Erin, er Whitney…

  70. Megan on June 17, 2014 at 9:58 am

    I’m so glad I started looking into this drug before giving it to our dog. I’m currently in Med school right now because I want to work in Phase I-II clinical trials. The drug companies are ruthless….they will do anything to push a drug because well to them it’s a “cash crop”. I want to go into this field because I’m not a “pill pusher” I’m a scientist. I would never work for a company that would want me to “adapt” my results in order to get something on the market quicker. Unfortunately people do not all have the same morale as I do….and I believe that this drug was pushed out into the market before all conclusive data/analysis was researched. It’s sad and it completely breaks my heart because in med school you make an oath to practice medicine HONESTLY. I guess some have lost the meaning of that word along the way and exchanged their morales for fraudulent behavior. I’m really curious about the research and testing results they have conducted. They say that they haven’t made any corelation between the dogs who have taken trifexis and died. But I don’t think they are looking in the right place. Sometimes in research your mind gets overwhelmed by conclusive results and it leads you to stop asking questions. I’m a naturally curious person though so I like to even question my own results to see if they are lacking any substantial material that could lead to problems down the road. My question is have they looked into the corelation between the dogs that have died from taking Trifexis and the previous medicine they were on? I know that Interceptor and Sentinel were very popular before the shortage happened and were taken off the market to only be replaced by Trifexis. What I want to know is how many dogs have died from Trifexis that were previously taking one of these medications. I honestly think that is where they need to be doing their research. Maybe the two medications have severely adverse effects, if one medication taken previously had changed something in the make up of the dog then the next medication used could’ve killed them because of this. This should’ve been taken into account when doing testing/trials. It’s like a human currently or previously using warfarin, it’s a heavy blood thinner. They are NOT I repeat NOT suppose to be using OTC aspirin because both medications do the exact same thing (blood thinners) and it would lead to a server reaction. If you think about it Trifexis and the previous medications are “essentially” used to treat the same thing so why wouldn’t this do the same thing if the other meds permanently inhibited the dogs system? Anyways sorry for the rant I’m just really curious about this and my heart sincerely goes out to all of the fur babies that have been taken away because of this. I hope that justice is brought to you soon.

    • Will Falconer, DVM on June 17, 2014 at 11:50 am

      Hi Megan,
      While I think it’s possible there could be prior drug interactions here, I also see that Trifexis alone is a significantly toxic drug without a prior drug history. You can see, even in the comment above from JB about an 8 mo. old pup, it can cause mayhem with health all by itself.
      The key I think is that when research is done by a company selling a drug, that research will never be unbiased: the profit motive takes over and that’s a larger incentive than finding the truth and reporting it. Data can be and regularly is skewed to make a good show of the profitable drug.
      Thanks for joining the discussion, and all the best in your training and future research.

  71. Jan Harris on May 8, 2014 at 9:06 am

    Dear Dr. Falconer, The AVMA (American Veterinary Medical Association) had opened a page on their website for discussion about Trifexis: and although the opening statements by the AVMA indicated that the “rumors” about Trifexis were absolutely false, MANY pet owners and some veterinarians contributed to the discussion about the tragic things that they had experienced. Today, I noticed that the AVMA’s page about “Trifexis Rumors” was missing on their website and emailed them. This is their reply:
    We welcome opportunities to provide a discussion forum for our members and the general public, and we believe our post about possible concerns related to Trifexis reflects our desire to help educate and inform about pet-related issues. As time has passed since we posted the blog item in November, most of the recent posts are individual, anecdotal comments that may not be a fair reflection of the actual situation. We simply don’t know, and therefore we are concerned about not portraying a fair and factual representation of what is happening with the product. If you have comments or concerns about this product please contact Elanco at
    Kimberly A. May, DVM, MS
    Assistant Director, Professional and Public Affairs
    Communications Division
    American Veterinary Medical Association (AVMA)
    1931 N. Meacham Rd, Suite 100
    Schaumburg, IL 60173
    Is that a jaw-dropper? They “welcome” discussion about Trifexis as long as nothing negative is said about the product. And how do you like the sentence: “most of the recent posts are individual, anecdotal comments that may not be a fair reflection of the actual situation.” !!!! They are dismissing pet owners actual experiences saying they are not a fair reflection!!!
    I’m honestly speechless. I wish I had copied the stories and discussion that the pet owners and vets had contributed – now they are gone forever.

    • Will Falconer, DVM on May 8, 2014 at 4:24 pm

      Hi Jan,
      I was actually more surprised that they allowed as many comments as they did! There were so many people calling out the illness they saw after giving the Trifexis that it was remarkable the AVMA allowed it on their very conventional site.
      My guess is the moderator got tagged by Elanco and asked to take it down.
      No matter. It’ll still sprout elsewhere, like the FB page I linked to. It’s hard to suppress the truth.

      • Jan Harris on May 9, 2014 at 7:06 am

        I pulled up the cached page, and am in the process of putting it on my website so folks can read it. Shame on the AVMA.

        • Will Falconer, DVM on May 9, 2014 at 8:32 am

          Great, Jan. Email me the link when you’ve got it up, as I’ll need to update my earlier post now.

          • Jan Harris on May 9, 2014 at 9:36 am

            Unfortunately, the snapshot taken May 5, 2014 contains only about half the comments submitted to the AVMA website, wish I could have gotten them all:
            And you’ll love this – Dr. Kimberly May (AVMA vet who started the page and then removed it) emailed me and said that the page was never meant to be a [quote] “venting site.” !! Calling the personal and heartbreaking experiences of pet owners “venting” was atrocious, I thought.

  72. Will Falconer, DVM on April 21, 2014 at 10:21 pm

    Way to go, Erica. You’ve got two shining examples of Vital Animals that no dog person could possibly ignore. A story with a real, vivid outcome like this carries more weight than any amount of advertising or lecturing ever could.
    I’m glad you’re an ambassador for a better path.

  73. Erica on April 21, 2014 at 10:50 am

    Took the dogs to the intramural fields to run and play frisbee. Met a nice lady that said her dog wasn’t feeling well bc she gave him his Heartworm meds last night…he was sick all night…everytime she gives it to him he gets sick (it was comfortis or Trifexis I think bc she said it’s his flea pill too.). She had a dog with heartworm in the past and that coupled with the heartworm model on the vet’s counter scares her enough to have to shove the pill down her dogs throat every month (he’s learned not to take it willingly…likely bc he’s made the connection with how it makes him feel).
    As her dog moseyed along sluggishly, my dogs on the other hand looked strong and healthy and were tearing up the fields snagging the frisbee outta the air.
    She commented on how great they looked. I told her how we stopped all the chemicals a few years back ever since we switched to a raw diet. She said that was the first she’s heard of someone doing it, asked what that was and where to buy it. I told her a little about it and pointed her in your direction so she could get a vet who would support her. I urged her, at the very least, to just give HW meds (Heartgard) every 45 days and stop the combo pill. I also introduced her to nematodes. It was nice to run into someone so foreign to this other way and not immediately met with resistance. But we are seriously killing our pets with love. I was guilty too. Fozzie absolutely refused comfortis 2 years ago so I switched to Heartgard and the spot on. Thank god we’ve finally found the path to true health (Toxic free pest control and a species appropriate diet) because I truly have some vital looking dogs. And she noticed. That’s something you can’t argue with.

  74. ELIZABETH on April 20, 2014 at 10:08 pm

    It is so good to see an ethical Vet take a hard stance against dangerous oral insecticides and put dogs’ welfare above profit. Thank you for coming forward.
    After my young dog went into a non stop cluster seizure lasting 90 minutes until I got her to the ER,(where she was put on an IV drip of Phenobarbital and Valium for 24 hours ) i was shocked to learn the ER Vet had many dogs who had cluster seizures. These Vets had plenty of experience with these horrible seizures that would result in death without ER intervention.
    Later when I realized that it was the Trifexis that is causing the seizures, i was surprised that the Vets refused to see the relationship between seizures and this oral flea poison.
    I asked the Vet how many of his cluster patients were still on Trifexis, and he said, “All of them”.
    25 years ago you rarely heard of dogs having seizures or getting cancer, unless they were very old. Now, it is common place.
    I’ve read Trifexis costs less than ten cents a pill to make, but retails for $20+ dollars a pill. That’s a lucrative incentive for both Vets and drug reps to pocket the profits, accept the drug company’s reassurances, and refuse to see the obvious link between Trifexis and the poisoning symptoms in dogs being brought to their ER’s.
    The profits to an individual Vet’s practice in selling Trifexis must be huge.
    How much markup/commission does a vet make off each six pack of Trifexis they sell? What is wholesale cost of Trifexis to the Vet compared to the MSRP?

    • Will Falconer, DVM on April 21, 2014 at 10:18 pm

      Good questions, Elizabeth, all. More importantly, where in the veterinarian’s oath is the part about making a profit over using your brain to see and remove causes of illness you have control over?
      We just have to spend our money on those that “get it” and hope the others eventually come along with the growing pack who values the natural path.

  75. Elle on April 16, 2014 at 5:54 pm

    This may sound pretty simple, but in answer to Scott’s question, I’d have to share what Dr. Falconer shared with me when I was living in a flea-prone area of the country. If you suspect your dog has fleas, just comb her with a flea comb and keep a bowl of soapy water next to you. Should you find a flea or fleas, swish the comb in the soapy water and they’re dead. Do this daily through a cycle, which I believe is about 2 weeks (was that the Rx, Dr Falconer?) and you’ve rid your dog of fleas with a natural method, no chemicals, and have had a chance to get close to your pup at the same time.
    I believe there’s also a way to naturally rid your house or carpet of fleas. Is it Borax sprinkled on the carpet, DE or something else? I can’t recall.
    Also, Dr. Falconer has an ebook that covers the heartworm issue. What he said to me about that is once a year, have your dog tested for heartworm rather than poisoning his system just to prevent the possibility. If your dog contracts heartworm, then you can give him the medicine that removes the disease.
    Please correct me where I’m wrong, Dr. F. Thanks for everything and for all your wonderful advice over the years. I have the healthiest, happiest dogs in the world as a result of you.

    • Will Falconer, DVM on April 17, 2014 at 4:42 am

      Thanks Elle, but there’s quite a bit more on both to control these beasts and keep your Vital Animal free from hitchhikers.
      On my Non-Toxic Flea Control page, it’s actually the intent that the majority of the efforts be directed at the eggs and larva, 80% of the population of the fleas at any given time. Absent this, you’ll be spending a lot of time picking off adults.
      As to natural heartworm prevention, my book Vital Animals Don’t Get Heartworms lays out a holistic approach to making your animal bullet proof against developing these worms. If you merely test yearly without applying the rest of the principals of sound natural prevention you’ll likely find a positive test at some point, indicating worms have lodged in your animal’s heart. Treatment then is complicated, expensive, and toxic. Far better to thoroughly arm your animal with the tools of resistance outlined in this 50 page book.

  76. Scott on April 16, 2014 at 1:23 pm

    Dr. Falconer,
    Thanks so much for the article. I took my 1 year old Weimaraner off Trifexis earlier this year, after reading so many suspicious reports on the drug. Your article helped confirm my decision!
    Do you have suggestions for alternative prevention of fleas and heartworms?

  77. marina schonbauer on April 15, 2014 at 10:35 pm

    after reading all that i will never give my beautiful 4 legged friends Trifexis ever again!
    now what to do about flea, tick or heartworm ???????????????
    thank you!

    • Will Falconer, DVM on April 17, 2014 at 4:44 am

      Hi Marina,
      Two pages lay out complete plans to control these pests without danger:
      1. Non-Toxic Flea Control, and
      2. Drug Free Heartworm Prevention
      If you want to further understand these approaches, you can use the search boxes that appear at the bottom of most pages, like the home page. Just type in a word, like fleas or heartworm, and you’ll be presented with a list of every page that I’ve written that contains these subjects.

  78. sekholm on April 15, 2014 at 11:56 am

    I live in Europe & have used milbemycin tablets for small dogs per vets instructions but normally only 3 times each summer. I would like to know where this milbemycin is sourced? How do I find out?

    • Will Falconer, DVM on April 15, 2014 at 1:50 pm

      I’d contact the manufacturer directly, Sekholm.
      But, I don’t want to make too big a deal of source here. Milbemycin is a pesticide, where ever it’s made. Pesticides kill things. Therein lies the rub.

  79. Yankee Shelties on April 15, 2014 at 12:39 am

    I don’t use flea, tick or heartworm medication and it’s probably just my own personal bias, but you know, I have to wonder how much has to do with sourcing milbemycin from China.

    • Will Falconer, DVM on April 15, 2014 at 6:08 am

      I wonder as well. This part of the formula has a history of causing problems in the Comfortis version. A logical question then would be: where is it’s source?

  80. JB on April 14, 2014 at 9:52 pm

    I gave my new 8 month old puppy his first dose of Trifexis after my new vet’s recommendation because, “since it’s in one pill, it’s easier to administer than the alternatives.” (All of this before a friend thankfully recommended many of your and others’ resources.)
    Anyway, only a few days after this dose, this normally lively and happy puppy suddenly slipped into what appeared to be an EXTREMELY lethargic state; this behavior totally opposite from my time with him the month prior. He was having a hard time standing up and would barely walk without me helping him along. He also experienced head tremors–I had never seen this before, and it was quite alarming. He also had no interesting in eating or drinking.
    After almost two days of showing no progress, I brought him into the vet. He had a 104 degree fever and he was dehydrated. Per the vet’s recommendations, we put the pup on IV (for the dehydration), urinalysis, full blood work, chest x-ray, and finally a ultrasound. They did each of these one at a time, each one coming back showing completely normal results (excluding the blood test which showed slightly elevated white blood cell count.) The second day there his fever finally broke.
    All told, she prescribed a general antibiotic and recommended taking his temperature throughout the day to make sure the fever didn’t return.
    Waiting for my bill, I noticed a myriad of Trifexis signs all over, but didn’t even think that this could be the cause. Neither did any of the doctors, apparently, as it wasn’t mentioned even once after I told them during the consultation that he’d been given Trifexis only days earlier. I quickly became suspecting of this drug after only a Google search and about 15 minutes of reading. I find it kind of hard to believe that an issue of such large scale goes unnoticed by a veterinary practice. Who knows.
    Needless to say I’ve learned a lot about these toxic drugs since then and I’d never recommend this or any other “heartworm preventative” to anyone else.

    • Will Falconer, DVM on April 15, 2014 at 6:07 am

      Thanks for relating your story, JB. It is surprising this is not more top of mind, isn’t it? I think we can all help change that. The more who know about stories like yours, the more dogs will be saved from illness and death.
      I’m glad your young pup survived.

  81. Elle on April 14, 2014 at 8:13 pm

    OMG, Andrew’s story about his dog having seizures as a result of applying this flea control chemical brings tears to my eyes. And then I feel the terrible sadness spread as I think about all the unconscious people who buy this chemical and use it on their dogs because they love them and want to prevent them from getting sick. This is truly upsetting.
    I’m going to post a link to this article on the doggie listservs I’m a member of. We’ve got to spread the word. Thank you, Dr. Falconer, for these illuminating yet shocking exposés. Makes me wonder what kind of world we live in.

    • Will Falconer, DVM on April 15, 2014 at 6:03 am

      Elle, thanks for spreading the word. Clearly, there are stories that need to get out to a wider populace and that can’t be denied.

  82. Andrew on April 14, 2014 at 2:37 pm

    Excellent article. Our young healthy dog recently began having severe cluster seizures, each time after administering Trifexis. The most recent one continued unbroken for over an hour as we raced to get her to the 24 hour Vet ER.
    This last seizure was only 13 hours after giving her oral Trifexis, and we have eliminated all other possible causes of accidental poisoning in the environment. It can only be the Trifexis. And looking back, we found each seizure occurred shortly after giving her Trifexis. Cause and effect seem undeniable here.
    Our vet is now reconsidering the safety of using Trifexis, which he says is pushed by the Elanco sales reps far more aggressively than most other pharmaceuticals.
    We have had time now to research and reconsider the mounting evidence against Trifexis. Elanco’s attitude does not inspire confidence. I’ve seen Trifexis called ‘the Agent Orange of pet drugs’ in an online Amazon review of Trifexis. I will never give Trifexis or any other oral pesticide to our dog ever again. Thank you for spreading the word online to other dog owners.

    • Will Falconer, DVM on April 14, 2014 at 3:32 pm

      Good deductions, Andrew. I’m glad you found the info helpful and are stepping on to a more natural path with your youngster.
      All the best going forward.

    • susann thomas on November 4, 2015 at 4:30 pm

      ?? So what do we give our dogs for heartworm and fleas

      • Will Falconer, DVM on May 7, 2016 at 9:56 am

        Hi Susann,
        Two pages will be of interest to you:
        Thanks for stopping by.

      • Judy Godfrey on July 14, 2016 at 7:43 am

        There is an easy preventative for Heartworm. Guinness Beer, Black Label, Brewed in Dublin. 1/4 tsp per pound given orally at room temperature. Two weeks later do it again. Then monthly thereafter. It is all over the internet. Do your research. It has to be the Guinness brewed in Dublin, though. There is something about the hops in that particular one that kills and prevents Heartworm. For fleas, we use Vet’s Best on Amazon but you can also use coconut oil or food grade Diatomaceous Earth. Research these two items and you will find much information on them for dogs. You can also feed your dog the Food Grade Diatomaceous Earth over dog food (1 tsp per day) to rid the dog of worms and parasites.

    • Ronda Reisdorph on April 26, 2016 at 12:01 am

      I found this website after it was too late…I am so sad to say that we had to have our 8 year old German shepherd put down 2 weeks ago due to Trifexis. We moved to Hawaii in September with 3 healthy, beautiful dogs. After the first dose of trifexis my dog’s hocks swelled and filled with fluid. We took her to the vet where they did not know what was wrong but thought it could be an autoimmune disease that would cost $700 to diagnose? We said that we just wanted to treat the symptoms for now….they gave her high dose prednisone. The swelling was better but she developed a slight limp. When we gave her the next dose of Trifexis she swelled again although not immediately and the limp grew worse. I took her to the vet where they x-rayed her and said her gallbladder was swollen and again that she might have some autoimmune disease. All her chemistries were normal. I questioned the vet about Trifexis and was told that it only caused vomiting and diarrhea and since she did not have any of these if was not that. We continued with the prednisone which had other side effects like incontinence so I weaned her off of them down to 1/2 tablet once a day. I forgot to give the Trifexis dose on time and it was 6 weeks since the last dose…she was feeling better but had a permanent limp. The swelling had returned to normal and then I did the unthinkable…I gave them their Trifexis on a Thursday morning. The next morning she could not even support her weight and her joints were hugely swollen. I KNEW !! I took her to the vet on Saturday barely able to walk at all and in a lot of pain. I had to carry her in to the office. The vet diagnosed her with a completely severed ACL in one knee and partially severed in the other. We were devastated…I reported to him about Trifexis causing all this in my dog. He said that he reported it to the company but I never received a phone call from the manufacturer. I asked if we could wait a week to see if she improved with prednisone, tramadol and gabapentin. The next Saturday I took her back and we all held her while they put her to sleep…she was suffering and I could not put her through anymore. We still have our 2 miniature schnauzers but I am afraid to put them on any heart worm medicine. I pray that they will be ok…I need a solution and do not want to put them on drugs that could kill them. They are promoting Trifexis to everyone even after watching my dog die. What an insane world we live in when the people and drug manufacturers who are supposed to protect our beloved pets kill them to protect the $$ they are making while turning a blind eye to our suffering!

      • Will Falconer, DVM on May 4, 2016 at 10:19 am

        Oh, Ronda, what a heart rending story! Having lived in Hawaii for several years, and studying the quarantine system, I know your dogs were likely multiply vaccinated before they arrived at their new home.
        That, plus this drug, sent your Shepherd into a dangerous immune spiral that she simply couldn’t pull out of. I’m so sorry you lost her.
        The good news for the survivors is two fold: you needn’t vaccinate again (and shouldn’t!). No rabies law there, and they are now immune for life (review my Vaccine: Efficacy and Vaccine: Safety pages to ground yourself in this understanding).
        And second, I kept HW away from my patients both in Hawaii and her in Texas (and Florida, and other states known to have the parasite) with my Drug Free HW Prevention Program. So, get that going and don’t risk another dose of the Trifexis.
        I wish you all the best. It’s such a stress just moving to a totally different place on the planet, but adding the heartache of losing a family member in the mix makes it ever so much more challenging.

        • Barbara Gallander on May 10, 2016 at 2:18 am

          Something similar happened to me n just now putting it together. My shar-pei who was not quite 12 yet went to the vet for a check-up. She passed in flying colors. 3 mos. on trifexis and yesterday I had to put her down. Her whole abdomen was filled with fluid. Her gums were white my vet was speakless. So I put my baby girl down yesterday 2 wks before her 12 birthday. I know this stuff did this to her. I’m taking my other dogs off. Plz beware this product is deadly.

          • Will Falconer, DVM on May 11, 2016 at 4:53 pm

            Oh, Barbara, what a heartbreak. I’m so sorry you lost your initially healthy Shar Pei.
            Best to you in healing this deep wound.

  83. Jan Harris on April 14, 2014 at 1:13 pm

    You said it better than I ever could. Succinct, factual, and exposing Elanco’s whole bogus “necropsy defense.” If you are interested, one of our puppy owners taped a 40 minute conversation with Elanco, and is transcribing it for me now. It contains a few more surprising statements by the makers of Trifexis (including advocating giving it to a 3-lb dog, and saying that there have not been 700 deaths). And if folks really doubt the facts stated in the excellent article above – CALL Trifexis (1-877-352-6261) and ask them point blank: “What exactly WOULD be the necropsy findings IF the dogs did die of Trifexis?”
    Two things that scare the bejesus out of me are 1) How many non-reported deaths/illnesses have occurred – simply because the owners or attending vets didn’t make the connection between Trifexis and the deaths/illnesses? (My guess is in the thousands) and 2) Spinosad, the insecticide which I suspect is the main culprit has been approved as an “organic insecticide” and is being sprayed on our grocery store produce – the rationalization being “that it completely breaks down in 24 hours.” (!) (and yet it protects a dog from fleas for 30 days).
    Anyway, congrats on an absolutely excellent article – which I hope will be read by every dog owner.

    • Will Falconer, DVM on April 14, 2014 at 3:30 pm

      Thanks Jan. I found your page, linked in my post, to be quite valuable in helping me pull together the disparate pieces of the story. Thanks for putting it out there.

      • Terry on November 2, 2015 at 2:00 pm

        Three days ago we started our Cocker Spaniels on Comboguard. Midnight last night my four year old Cocker had a Grand Mal seizure. She has never had this problem before. The vet says seizure wasn’t caused by Combo guard and if she was going to have a seizure, it would have happened sooner and not three days later. I don’t believe this BS! I have an appointment to get her examined tomorrow. Do you think Combo Guard caused my dog to have this seizure? I do. If my Vet sticks to their story, I’ll change Vets. Seeing my companion going into a seizure like that ripped my heart out. I cried! I am a 66 year old man!

        • Ryan on August 2, 2016 at 1:00 am

          What was the outcome Terry? I hope your pup is ok.

        • Sylvia Olney on March 27, 2018 at 9:24 am

          I forgot to mention his labs. His platelets were so low, red blood cells very low. He had so many things going on. I’m taking this medicating back and getting our money back.

        • Sylvia Olney on March 27, 2018 at 9:25 am

          Switch vets. My vet was acting clueless. My dog almost died. The vet that sold it didn’t make the connection. Just sent him home saying dogs get sick sometimes. That’s what happens. He said just keep an eye on him. I took my dog to another vet which then referred to a specialist. They asked me what heart worm medication is he on. I had no idea the original vet had introduced this awesome new medication, Combo guard to my husband. After giving it to my dog, a few days later loss of appetite happened, then lethargy. My dog looked like he was dying. He could barely open his eyes. One was turning kind of greyish. Found enlarged pancreas, beginning of liver damage, kidney failure, incontinence. I’m so grateful that I did not listen to the first ignorant vet. If you introduce a so called new medication you claim is so awesome. You should know to be aware of any changes. Trust no one but your instincts. You know your pet better than anyone. VCA clinics should train the vets to gain more knowledge in the medications they are selling and pushing on people’s pets.

        • AMY KAY on October 7, 2018 at 4:49 pm

          My dog started having seizures. He also came down with a case of pancreatitis. Im starting to think it’s trifexis. What did you find out?

        • Sherrie Satterfield on March 25, 2019 at 1:52 pm

          I believe you sir, this product nearly killed my pet of 9 months. this is terrible that this can go on. My dog didn’t have a seizure but he should had some terrible and scary symptoms and I will NEVER give him this comboguard or trifexis to any of my animals ever.

          • JOLEE D KENNEDY on June 30, 2019 at 2:02 pm

            Sherrie: just wanted to say I am sorry you lost your pet. I appreciate your input as I am at a loss as to how to control insect disease in our dogs, both 10 years old. We have to choose between flea, ticks and heartworms or watching them vomit and suffer for several days after giving them Heartgard. Doc tried to switch us to Trifexis but then I read some of the reviews. The sample is going in the trash right now! We switched from Nextgard to Frontline for ticks and as it is not internal, and it does not seem to upset their tummies. But it is still poison I am giving them and it makes me nuts. There is no easy answer. In Wisconsin the insects are thick as thieves and we have to make hard choice.

    • Janice Rogers on October 17, 2015 at 9:35 am

      The vet started my dog on Trifexis 2 years ago when she was 11. She is now 13 and I have taken her off. She took the medication for 1 1/2 years. She is still not well, but I think she may be a little better. During the time she was on Trifexis, she experienced seizures, hypersensitivity, and vomiting. I had no idea that this could be a side effect of the Trifexis. My vet told me that at her age she probably had a brain tumor that was causing the seizures. Anyway, she had her teeth cleaned at the same time she started on Trifexis. Her labs were perfectly normal. 1month ago, she had to have some minor surgery and her labs were terrible. The vet said that she had chronic pancreatitis. I realized that all of her symptoms occurred after starting on Trifexis, so I asked him about it and he said that many of his clients were on Trifexis and that he had never seen any problems. He suggested that I put her on a low fat diet which cost me a fortune and she would not eat. So, I went to the Internet and looked up Trifexis and found that many people had trouble with it. I took her off of it and I have changed vets since. When I requested a different heart worm med from the new vet, she thought that I wanted to start Trifexis and she said that she needed to caution me against starting Trifexis on my pet at her age. I truly believe that all of my pet’s problems occurred as a result of Trifexis.

      • Will Falconer, DVM on October 17, 2015 at 10:13 am

        Oh, Janice, I’m so glad you stopped the Trifexis and learned first hand its dangers. Obviously, that was more than your vet was willing to look at. I can only imagine how many dogs are sick but still no one’s connecting the dots like you did.
        The blood profile is so telling. Can you imagine Elanco, being so focused on making profits off their pesticide, that they’ve never tested before and after blood values, like you did?
        Madness like this will only stop when people learn this stuff themselves, like you did. And, just like you did, then vote with their pocketbook: we’re not buying this product any longer, and we’re not taking our animals to the vet who refuses to look deeper.

        • Katie McLain on October 26, 2015 at 11:04 am

          Dr. Falconer,
          My dog is currently on Trifexis and I will never give him another dose. After reading this, though he seems fine, I am so afraid that damage may have already been done. What do you recommend for flea and heartworm preventative? Are there natural treatments that work?
          Thank you for spreading the word!

          • Brenda on May 4, 2016 at 8:09 am

            Katie, try garlic for flees & tics,and if you go to Canine Health Concern, and become a member (a few dollars or pounds per year) you will get ALL the natural non harmful treatments available.
            Bye B X

          • Anita tally on November 30, 2019 at 9:25 am

            What is your natural method of worm control in a lab who will eat anything including the ground where the worms are? Our dog is 21. Months olds do has only had two doses of interceptor plus . We have had her since she was 8 weeks old. Pure lab part American and English. Planning to spay her around 22 months of age. Letting growth plates finish. Vet does not recommend I’ve but will do it. Said they have seen problems with leaving uterus in.

        • Michele Damore on May 15, 2016 at 9:31 pm

          How long do you think it will take to rid my dog of the problems As a result of a monthly treatment

        • Matt Rocha on November 27, 2017 at 8:04 pm

          Are we nit supposed to give dogs heartworm medication?

      • Carrie on October 8, 2016 at 9:39 am

        So sorry to hear about your dog. I have my 10 month old gsd on Trifexis. She is constantly itching. I thought it was food allergies, nope, changed her food a couple times and now we’re on Simply Nourish. Still the itching. Thought it could be environmental but after reading about Trifexis I wonder if it could be from it. She also snaps at the air at times. Monday she will be due for her next dose. I am not going to give it to her to see if it helps with the itching. What do you use now for heartworm and flea preventative? Thank you.

    • John on January 6, 2016 at 4:57 pm

      My cockapoo has been on triflexis every month since he was 3 months old, he is now 3 years old and perfectly healthy and heart worm and flea free

      • Cody on March 16, 2016 at 12:48 am

        Yeah, my dog, a Shiba Inu, has been on Trifexis for years and he’s healthy and parasite free. Dogs have bad reactions to medication just like people.
        To say Trifexis is deadly and kills every dog is ridiculous. There are rare but serious complications with all human drugs too, yet people still take them! How many millions of people would die if they refused to take medicine because of “what happens in under 1% of those who take it?”
        Every time I see a commercial for a drug I laugh at the end when they go over all of the bad things that can happen. The list is a mile long.
        That’s why I don’t get it when people slam Trifexis for all dogs because of some reports that it harmed a dog. Yeah, vaccinations have killed people, yet most people are still vaccinated.

        • Will Falconer, DVM on March 16, 2016 at 7:28 am

          Hey Cody,
          “To say Trifexis is deadly and kills every dog is ridiculous.”
          “That’s why I don’t get it when people slam Trifexis for all dogs because of some reports that it harmed a dog.”
          Seriously? It appears you never even read the article, if you think this.
          I doubt if anything on this site will make sense to you, Cody. It’s not written for you, who are happy to take what Big Pharma serves you and not question it.
          I invite you to start your own website and gather those who think like you. This site is here for thinking people who aren’t afraid to question authority, especially when that authority is despensing risky advice and drugs.
          You’re lucky your dog is just fine on years of giving him a pesticide that’s clearly been associated with serious illness and death in many, many others. The fact that you know two other dogs who’ve been on this poison and aren’t harmed yet proves absolutely nothing.
          Carry on. There’s nothing for you here.

          • Cody on March 18, 2016 at 4:22 pm

            Correct, just because you think a certain way doesn’t mean it’s accurate or backed up by science. Yes, people like me, a progressive liberal, atheist, who has no tolerance for unscientific views.
            All medication can cause a rare but serious complication. To stop using science to our benefit because of any risk would be foolish.
            The fact of the matter is the government does in fact regulate and pull down products that cause excessive harm or death. So my views may prove nothing but the fact that this product is still available on shelves world wide proves plenty.

          • mari adloh on July 7, 2016 at 9:16 am

            some people just have been so brain washed by the media AND the big pharmaceutical corporations for themselves and their animals that NOTHING you say or SHOW them will change their minds always have a excuse
            so i say if it happens the their dogs they will say old age or genetic or thats how long a dog lives???
            oh well good for them,,,, i will not put something in my dog or on my dog that I CANT TAKE and when it says wear gloves and wash your hands after using!!! the big red flag goes up
            its just a sad day when you cant trust anything you read you have to research everything you feed or give a animal
            you have to do your own research and not take their word for anything use your brain that’s why we have one

          • Laurie Johnson on September 24, 2016 at 5:23 pm

            My reply is directed to Cody. I was fine with your comment until you said that ‘the government does indeed Regulate and Pull Down Products that cause excessive harm or death.’ This statement could Not be further from the truth!!! Also the fact that Trifexis and other Dangerous drugs are Still On the Shelves Does Prove a Lot! It Proves just how Greedy Greedy Greedy these government agencies are! They are All in bed with Big g Pharma, Big Ag, and Big Business!!!!! They are so Corrupt it just makes me Sick!!

          • Louise on December 2, 2016 at 1:21 pm


          • anna on June 16, 2018 at 9:30 pm

            My 7 years old Maltese used Trifexis for 6 months, when we came from S. California to Florida. No problems , I’m getting her more from Canadian Pharmacy “VetExpress” —It is about 35USD cheaper, than in US.

          • Zoe on November 30, 2019 at 9:00 pm

            Will, you are incredibly rude for someone that holds the profession of DVM to respond to people in such a condescending way. My Labrador retriever has also been on Trifexis since she was 7 yrs old with no problems whatsoever…she’s now 12. Although I do agree that pesticides are deadly, my Labrador only eats raw meats/fish, veggies, and broth, gets acupuncture on a bi-weekly basis and takes Chinese herbal formulas as well as milk thistle to keep her liver healthy. Even though she’s 12-years old, people still comment that still looks/act like she’s 5-6 years old, while still being on Trifexis as required by most boarding places. I sincerely hope you don’t talk to your clients like that in person or you would most likely be out of business!

        • Marie on April 8, 2016 at 1:04 pm

          Cody – It’s so incredibly sad to me that you have such little compassion for other’s lives: “Yeah, vaccinations have killed people, yet most people are still vaccinated.” Take some time to research this, there are hundreds of thousands of people living with illnesses tied directly to vaccines, OTCs, environmental chemicals, conventional farming practices. These are the mystery illnesses and autoimmune disease “your body attacks itself” BS that simply clears a doctor and entire scientific community from their lack of understanding in how the human body works. The human body does not attack itself, that’s completely false and undermines true health and hope.
          There have been great advances in medicine but in chronic illnesses, it’s failed miserably. The funding and testing are just not there to really make a positive and lasting difference in true health.
          I value personal responses or reactions far more than scientific studies. Scientific studies are incredibly flawed and the ones that are created without ulterior motives are buried quickly with the hundreds of thousands of silly studies all funded to promote someone’s profits. I also trust my gut over any sterile lab, in fact, anyone that undermines my intuition is a red flag. You might want to get outside and stand barefoot on the ground. Yes, this is an ancient technique that grounds one and the benefits of it could never be fully measured in a lab, nor does a lab care to measure the benefits of grounding unless someone can patent and profit from it. Critical thinking is pretty easy, anyone who defends the BS, to me, is either paid to do so or just disconnected.

          • Kathleen on April 11, 2016 at 8:34 am

            Hi Marie,
            I wouldn’t worry too much about Cody. His words sound exactly like they are from a drugstry (drug industry) script. Drugstry shills are hired to manipulate public opinion. All large industries use this deception. Here is medical investigator, Sharyl Attkisson, giving her TED talk on front groups/astroturfing.

          • D Frye on July 27, 2016 at 5:20 pm

            You mention ” These are the mystery illnesses and autoimmune disease” yet you attribute the illnesses to specific drugs. If tested and shown to be caused by a certain drug the illness is NOT a “Mystery Illness!”
            And if parasites are killing my dog, what do you want me to do? Wish them away? Try some Holistic treatment that doesn’t work, leaving her in misery for months?
            I will listen to my vet; check the label, check the facts as best I can and go with what we decide is best for my pet. While I agree that some medicines, Trifexis included, can cause severe side effects, if every natural treatment, and every topical treatment has failed, I will give it a try.
            Good luck

          • JR on August 24, 2017 at 3:58 am

            Right, because the settings in people’s homes are so secure against alternatives that can sicken or kill the animal, versus a scientific study that is very controlled!
            Also, the very manner that this “report” is written in drips lunacy. A more professionally written paper would give a little more credibility, but starting off with a title with B.S. in it automatically starts to lose points. If I was researching a paper, as one person said everyone should do, this not the paper I would lean on just because of how the author decided to put his work out there.
            Cody seems to be right on point in several of his comments.

          • April Sanford on June 14, 2018 at 5:52 pm

            Marie, I think we’ve witnessed the birth of a Sociopath or two. First off, no one said, “Let your dog suffer with worms while you give her holistic treatments that don’t work”. I read and re-read. If you don’t agree with the Article, you don’t agree with the Alternative Treatment and don’t share the opinion of the General Consensus so wtf are YOU doing here? Seems to me you want to sow some seeds of dissent amongst a group of people who are peacefully exchanging info and support. Yeah, you SOUND REALLY PROGRESSIVE, my “liberal” friend.

        • Vanessa on November 10, 2016 at 11:39 am

          I concur Cody. I’ve been rescuing/adopting and treating all kinds of dogs – but mostly large and giants as they are harder to find homes for – for decades (no I shall not divulge my age hahaha) I’ve been using products such as Program and an ivermectin/pyrantel med for heart worms since 1985 (when I graduated from med school … people med, bc I love animals more!) and was able to have dogs in my own home. I’d used the same vet from ’89 until his recent death in 2015, and he was always amazed at the longevity of all of my large breeds! egs. Gr Dane lived to 13 yrs, Newfie to 14, etc. Maybe it’s luck/good karma/love I don’t know, but I have had no reactions to any flea/heartworm meds (including Trifexis) – that would be in 21 dogs. When I was in med school and the pharmaceuticals were cost prohibitive I did use garlic etc. but I did not know of a heart worm substitute.
          Now I do continue to use meds for fleas and heartworm, but I am SO sad that these kind dog lovers and owners have had such tragic events! I wish I could figure out what I am … I guess, what I’m doing right … and/or send my good fortune to you all!
          And to those people who have not experienced any untoward effects – that’s awesome! As an MD I do use medications, however if someone shows me an alternative therapy that works, I’m all ears!

        • Stacey on July 8, 2019 at 10:11 pm

          If your pet started convulsing and then seizing or acting lethargic after you gave them medicine would you continue to give it to them? My 7 yr old Shih tzu has been a healthy dog and started seizing in January after giving her trifexis. Then again in March in April the seizures started getting closer . Instead of happening once a month they were every week. I stopped giving her trifexis in May and so far she hasn’t had any seizures. I am going to try to find another way to treat her for heartworm. We wash our produce before eating it because of pesticides. Yet we cram a pill loaded with it down our pets.

      • Scout on March 22, 2016 at 10:19 am

        We have 2 Beagles Leo, and Droopy who are 9 years old now and in very poor health. Probably will not be with us much longer. By the way they are city Beagles who live inside and are walked everyday twice a day and their weight has been controlled all their lives. We live in Western NC. We fell into the trap of thinking they needed the parasite treatment since they were old enough to take it. They become sick for a day every month at pill day. We ask our vets and were told you need to weigh the risk if you stop the treatment. Being Beagles as some of you know they will grab and eat anything they find when walking them if I am not fast enough to keep it from them. Then within a few days it was off to the vet and we were always told they picked up a parasite. I Always ask I thought the parasite prevention meds stop that. Always got a BS excuse from our vets.
        Two years ago we started seeing tumors coming out on both dogs. At their annual Checkup and shots we ask about them and were told it’s just something that happens to some dogs. Hard for me to believe both dogs have the same condition at the same time. Then we were told that they needed the heart worm test twice a year. I ask why if they had always been on it would they need tested. Got another BS excuse from the vets. I then told the vets my dogs would not be given parasite meds anymore I had read the stories on the web. One of the assistants told me she was calling PEDA and letting them know I was a bad pet owner. We have been receiving reminder cards monthly for months now telling us it is the law that we get them parasite tested, more BS.
        Anyway I think it is a money thing for the vets
        $35.00 for the test
        $45.00 for a office visit
        $30.00 for the parasite meds
        this is per dog.
        The big question here is would you put this in your body?

      • Rachelle Keeney on February 7, 2018 at 4:51 pm

        I have 3 dogs on Trifexis 6 years. Terrier mix, short-hair. Ages; 12, 11, and 7. Weight; 20, 12 and 12 lbs.
        They are very active, playful dogs on a high protein, fruit/vegetable diet. ‘Grain-Free’. No junk food, no fat, sugars, salt or starch extras.
        They have been on Trifexis going on 6 years with no problems or side effects.
        It is necessary to observe closely and know their behavior to notice slight changes because they are so good at hiding things. They do slow down a little and rest for the day but nothing unusual. Trifexis has worked very well for fleas, ticks, worms.
        We also drive a lot of long distance. Trifexis is a safeguard that has worked.
        As an added back-up with benefits, we also use for our dogs, cats, chickens, ducks and deer …
        A safe, effective, ALL-NATURAL SOLUTION for fleas, ticks and intestinal worms.
        Sparingly, add a light dusting of Food Grade Diatomaceous Earth on to all animal feed. Also, lightly dust on their fur and / or bedding and areas as needed.
        “DE” is natural silica sedimentary rock that is an off-white, super-fine powder. Having so many health beneficial uses -for pets and humans.
        Very inexpensive. Available most everywhere, cheapest on eBay.
        Make sure it is labeled FOOD GRADE that is safe for ingesting.
        Here is a (copy and paste) link for DE benefits and uses:
        For pets; https://www.diatomaceousearth dot com/diatomaceous-earth-for-pets/
        For humans; https://www.diatomaceousearth dot com/diatomaceous-earth-human/
        DE also works on ants, roaches and bed bugs like glass.
        With microscopic abrasive properties, -Keep clear from inhaling and eyes.

      • Kobe on March 12, 2020 at 10:08 pm

        Same as my cav, he was on trifexis since puppy now he is 9 years old.

    • Eddie jank on March 28, 2016 at 7:42 pm

      It’s one thing too run down the product what do you do for a dog that craves dirt.every pile of wild rabbit poo I find is filled with worms chocolate to my dog .I held brownie while I watched him almost die from parvo all the vets charge 150 too 200 a month for visits it sounds like the best things for me is too just put him down now so he won’t suffer any heart worms he’s only 4 months old we just don’t want our animals to suffer. Do you always call your doctor a liar. it may be the leaset of all the other chances of them dying a real sad dog owner eddie

    • Mazzy on July 5, 2016 at 7:30 pm

      I have a story for my animals too. One dog was lathargic for days after dose of the 6th cycle, and the other didn’t eat for three days. She adamantly wouldn’t let me give it to her and I didn’t listen and now feel terrible. Also, after the 6th cycle I started noticing large patches where her hair stopped growing. Needless to say we stopped go on. The product immediately. Now I have 240$ of product sitting in the drawer. 🙁 this was prescribed by the bet so I didn’t even think about checking it.

    • Shirley Jackson on September 23, 2016 at 10:14 am

      What would you recommend

    • Linda Anthony on January 22, 2018 at 7:30 pm

      Hi Shirley,
      I would very much like to access that audio. I live in Australia and my cat died 3 hours after taking this tablet. It is called Comfortis here. There are many deaths online or serious illness in dogs and cats and I plan to ensure this is off the market.My cat was only 6 months old and perfectly healthy. She let our a horrifying and painful scream and was dead instantly with vomit beside her. Gave her this tablet at 5.30 and she died just after 8pm. I could not afford the $1500 autopsy to find out what killed her but from what I’ve read online by users I am convinced it was this medication.