Neuter. Or Not?
And When?

Not Black and White

You need to neuter your animal, right? I mean, that’s just basic: there are too many unplanned pregnancies, too many euthanasias because of that, and you need to be responsible and just do this.


What was once a very stock recommendation to all my puppy and kitty owners has evolved as new research findings have emerged of late.

And, in fairness, as I’ve dug more into the seriousness of the outcome of neutering, I had to leave the comfort of “one size fits all.”

Damn inconvenient, grumble mumble… why can’t biology be more like auto mechanics?

My newer recommendation goes something like this now:

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If you can prevent unplanned pregnancies, (and if you have a female and don’t mind living through heat cycles) you may want to keep your animal intact and not neuter.

Emphasis on “if” on the pregnancy question — I’m not wanting unplanned pups or kitties any more than those on the front lines in shelters and rescue groups who see way too many of them.

Oops is not an option.

It’s interesting to note, however, “Everybody Must Get Neutered!” is a uniquely American notion. Probably born in the last 20 years, would be my guess.

Europeans don’t buy this idea.

A Swedish study of 461 dogs revealed 99% were intact, not neutered.

A Hungarian study showed 57% intact dogs, and a British survey found 46% intact dogs.

Hmmm. Do they know something we don’t?

What Happens When We Neuter?

I like to call it “instant menopause.” You know how rough life can be in peri-menopausal or menopausal times, either from your own experience or from your mom’s or wife’s?

Imagine that all being condensed into the flip of a switch.

I know in my mom’s life, a hysterectomy was the beginning of a very significant downward spiral in her health when she was in her 50s.

Sex hormone production is mostly in the testes or ovaries, though a smaller amount is produced elsewhere, for example in the adrenal glands.

When spaying or castration (collectively called neutering) takes place, we shut off the major source of the sex hormones testosterone, estrogen, and progesterone.

While neutering prevents pregnancy, you have to evaluate the risks against the benefits to decide where the balance point is for you and your animals.

Clear Benefits

The good that comes from neutering is:

  • Birth control
  • Cessation of heat or estrus cycles
  • Absence of behavior that goes with the sexually intact animal

Birth control is the main reason neutering is pushed. Once the male loses his testicles to the surgeon’s knife or the female her ovaries and uterus, neither can create offspring from that point forward.

Estrus cycles are those periods of time when the female is in heat, surging with sex hormones, and both attractive to and receptive to the male.

Heats come typically every six months in dogs, seasonally in cats (usually spring and fall), throughout the year in cattle, and seasonally in early spring in the horse.

This all goes away when a female is spayed.

Behavior accompanying heat cycles can be both annoying and downright dangerous. Annoying is the female cat who comes mmrOOWWWwwwing at all hours, keeping you up at night with her chorus of lust.

Worse yet is the tom cat’s constant urge to leave his scent everywhere with a spritz of urine on doorways, furniture, or your shoes! Intact female cats will also “soil” your house with urine while going through their heats.

I was recently visiting my network chiropractor’s farm while her intact Dachsund was just going out of heat and her intact male Airedale was beside himself with desire, but locked up behind impenetrable fencing.

Poor Lionheart! He didn’t even recognize me when I came up to rub him and say hello. It was like I wasn’t there, and I was told he’d missed eating for several days, he was so taken with the lusty hormones he was smelling from Frieda!

The dangerous side of behavior in this instance comes from running out into traffic in “hot pursuit” of a female or, like Lionheart, running through a barbed wire fence, lacerating his penis, and bleeding for days!


There’s data out there on animals hit by cars: far more are intact than neutered.

And yep, it’s usually the guys.

Another danger is male aggression, though this is largely a cat issue, and in my experience much less likely in intact male dogs.

Tom cats are prone to getting into serious fights when they are intact, and this can make for wounds, abscesses, and disease transmission, if they are wounded by a cat carrying FeLV, for example.

All of this behavior, the heat cycles, and the possibility of pregnancy are gone once you neuter. (I cannot personally imagine living with unneutered cats, unless you relish the scent of cat urine!)

Downsides and Risks

What’s become of greater interest to me of late are several studies showing the ill effects of surgical gonadectomy, or instant hormone-pause.

A study done in UC Davis and published in February 2013 revealed some startling health consequences of neutered animals, both male and female.

The research tracked 759 Golden Retrievers, and looked at early neuter (less than one year of age) vs later neuter (12 months or older) vs intact dogs and five common diseases:

  1. Hip dysplasia (HD), the arthritis of the hip joint common to dogs
  2. Cranial cruciate ligament (CCL) damage, the “football injury” of dogs’ knees
  3. Hemangiosarcoma (HSA), a type of cancer that can be fatal
  4. Lymphosarcoma (LSA), immune system cancer, usually fatal
  5. Mast cell tumors (MCT), yet another cancer that can kill dogs

To summarize the researchers’ findings:

  • Neutered animals fared significantly worse in all five diseases.
  • Early neuter of males doubled the rate of hip dysplasia compared to intact males.
  • None of the intact animals had cruciate ligament disease. Zero. It only appeared in the neutered animals.
  • Early neutered males had three times more LSA than the intact males, while late neutered males had no LSA.
  • The percentage of HSA was four times higher in late neutered females than in either intact or early neutered females.
  • MCT was absent in intact females but present in neutered females. In males, neutering status made no difference.

So, in dogs of both sexes, neutering had significant ill effects in this large study, though it wasn’t uniform across the board.

The clearest loser: early neutering, which has always made holistic veterinarians cringe.

But, in fairness to how facts aren’t always clear cut (damn them!), you noticed how early neutered female Goldens had less HSA?

Still not a good reason for early neutering, as you’ll see below.

Here’s an earlier study (2004)1 on cranial cruciate ligament injury that also showed an increased prevalence in the neutered dogs, male or female.

Early Spay: No Way!

We’ve known for many years that it takes intact sex hormones to grow naturally, with skeleton and ligaments and tendons all in harmony.

The proponents of spaying or castration at a very young age, long before maturity, have ignored that in favor of some desperate “get ‘em while we’ve got ‘em” mentality.

This is somewhat akin to what I call “steer in the chute” medicine.

If you’re a rancher and you only work your cattle infrequently, due to handling stress, manpower, weather, etc., you tend to do as many things to that captured animal at the moment he’s caught in your chute as possible.

So, steers are commonly castrated, branded, vaccinated for multiple things, ear tagged, and fly treated before they are released.

It’s convenience medicine, in other words. “We might not see him again for months, let’s get ‘er done now!”

So, shelters and humane societies got the bright idea some 20 years ago to start neutering dogs and cats when they were 8 weeks old.

Imagine giving your 9 month old daughter a hysterectomy, and you’ll cringe appropriately.

And yes, giving vaccinations while under anesthesia is a common practice.

No chance of struggle. Never mind that the immune system and all its defenses are asleep as well. “She’s in the chute, let’s do this!”

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Crooked and Crazy

This study showed the disastrous effects early neuter had on development, when it occurred in either of the ages studied: 7 weeks or 7 months, vs intact.

Bone conformation was distorted (radius to ulnar length), genitals and urinary tracts failed to develop properly, and both groups of neutered animals were “more active”, with the 7 week neuter group judged more “excitable” than the intact group.

Wait. What?

Ever see an ADD dog? One who can’t stay on task, easily distracted, over excited by most anything?

This isn’t the only study that hints at behavioral effects like ADD in neutered animals.

Here’s another, showing even aggression far more in neutered vs intact dogs in a large population study.

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Among the findings, neutered dogs were more aggressive, fearful, excitable, and less trainable than intact dogs.

Damn. And clients are asking me regularly if keeping their male dogs intact risks them being aggressive.

These data suggest the complete opposite.

The researchers above also measured bone lengths and found abnormalities in the neutered.

[Now, in fairness, a variable was not factored in here, one I see as significantly important in creating the excitable, ADD-like dogs who regularly grace my practice: vaccination. I asked the chief author of the last paper if vaccine status was taken into account. It was not.]

More Fuel for the Risk Fire

An earlier study on osteosarcoma showed twice the incidence of this deadly bone cancer in neutered vs intact dogs.

A study of dogs spanning nearly 40 years and over a million dogs (!) confirmed that female hormones are protective against lymphoma, a cancer that takes over the immune system.

Their working hypothesis came from the observation that women don’t get this disease until after menopause. And yes, that’s the state we induce immediately after spaying. Bye bye, female hormones.

Hypothyroidism in Dogs — Highest Risk: Neutering

Here’s a study from 1994 of 66 dogs studied over five years, and the researchers found neutering was the “most significant … risk factor” in the dogs becoming hypothyroid. Vaccines are another, per Dr. Jean Dodds.


We’ve known for many years that spayed female dogs develop urinary incontinence later in life. Until it was taken off the market for safety reasons, the standard treatment was giving estrogen replacement. Remember, ovaries are the main estrogen producers.


The neutered animals tend to get obese more easily than their intact cohorts. This has been studied in cats as well as dogs. This has also been commonly seen in practice over many generations of dogs.

I strongly suspect that this is due to carbohydrate laden foods (i.e. kibble) being fed to carnivores, especially the cat. You can have a big influence here by making good feeding choices in both species.

Beware: Red Herring

You’ll hear this argument in favor of spaying that’s based on real life observations by Dr. WhiteCoat:

Unspayed females (dogs) are more likely to get breast tumors than spayed females.

But wait.

I’d ask you to put this in the only context that will shine a light on it: the wild model.

Look to the closest cousins, genetically, to verify this.

Are intact wolf bitches succumbing to breast cancer? Coyotes? Dingos?

I seriously doubt it.

This is a disease of man’s interventions, like every other chronic disease you can name in domestic animals.

These animals with breast cancer were likely multiply vaccinated, for years if not for life.

They were likely fed kibble, a very species inappropriate diet, full of toxic byproducts, preservatives, and starches.

They may also have been treated with the ever present flea pesticides.

Add in the risky heartworm drugs given monthly, and you can imagine spaying was perhaps one small reason for their disease.

Intact wild canines who live free of these influences would not be dying of breast cancer.

Pyometra, Red Herring II

You’ll often hear this argument for spaying as well: spayed females don’t develop pyometra, the infection of the uterus that can be life-threatening.

Well, that’s true: one can’t get an infection in an absent organ.


But again, look at what’s happening in the real world.

Do lynx and wolves die of pyometra or is this another man made disease? I’ll bet you can answer this yourself.

What’s a Thinking Pet Owner to Do?

Let’s break it down to four groups and I’ll offer my take on this neuter question as a guideline for you.

Ultimately you have to answer these questions for yourself, in your living situation to decide which way to go for the animals in your life.


This may be the easiest for me, having grown up with one male dog at a time throughout my youth, none of whom were castrated.

Looking back, I realize now that we were careless some of the time, letting our guy out to eliminate on his own.

There were a few times we’d not see Jake for the rest of the night, only to have him drag himself in, exhausted, the next morning. My dad would make a joking remark about “visiting girl friends,” and we moved on after a laugh.

That meant unplanned for puppies somewhere.

Not good. Irresponsible.

None of our intact male dogs were aggressive in the least.  None were given to mounting or undesirable sexual behavior.

N=4 (science term for the number in the study).

Q: Can you prevent your male dog from wandering the neighborhood?

Good fencing and/or leashing and supervision when he’s out to eliminate would answer that seasonal wanderlust.

Wandering uncontrolled not only makes puppies, it can make for auto injuries or death.

A: If you’re confident you can answer yes, I’d recommend not castrating your male dog.


This one’s also pretty easy.

Having seen beat up intact male cats in practice, with a thick neck and a scarred face, and knowing that they, in their territorial imperative as breeding males, were also marking their territory (to include, but not limited to, their owner’s personal things and living space), these guys need to be neutered.

When will come in a bit, read on.

The only exception would be someone with a carefully planned breeding program who is set up with a cattery.


The data here clearly show risk from removing the ovaries, which is part of spaying. So, we’re back to a couple of Q’s and A’s:

Q: Are you confident you can prevent pregnancy for a few weeks twice a year?

A: If yes, I would keep your bitch intact, not neutered.

Q: Are you comfortable with diapering for a couple weeks every six months to avoid blood spotting on your bed or floors?

A: If yes, not spaying may be appropriate for you.

Time Out for the Big Picture

An important BUT comes in here, however.

If you aim to raise your dog the way I advocate, with no vaccinations after the initial couple as a youngster, and feed a species appropriate diet, and avoid the poisons foisted on you in the name of flea and heartworm control, you’re likely to avoid pyometra and breast cancer.

If you go for the Dr. WhiteCoat version of “prevention” instead, you’re likely better off spaying.

Like so much of biology, health and illness is usually a combination of many decisions you make for your animals, all rolled together.

Hence, the need to approach health holistically.

Have you found your holistic vet yet? Or better yet, your homeopathic vet?


Again, with the exception of those planned for a breeding operation, if you don’t relish amorous behavior several times a year with urine marking and the neighborhood toms hanging around spraying urine and fighting outside your dwelling, I’d recommend spaying your adult cats.

The data of ill effects of neutering are largely from the dog world. Cats may follow suit, but we don’t typically see bone cancer in cats, nor HSA, or MCT.

LSA, the cancer of the immune system is not uncommon, but it’s not been studied in intact vs neutered cats, to my knowledge.

We can say there are protective effects of having one’s ovaries intact in both dogs and humans.

When to Do the Deed?

If you’ve decided to neuter, after weighing risks and benefits, timing is everything.

Growing to maturity with one’s hormones fully intact is best. I’m speaking here not of sexual maturity, but the cessation of growth and the closure of the bone growth plates.

Maturity comes at different times in different breeds.

In general, the smaller the adult weight, the sooner maturity will set in.

That might be 9 – 12 months in the wee breeds, and up to two years in the bigger guys, like Danes and Mastiffs.

This is even true in cats, with Maine Coons thought to not reach full maturity until they are two years old.

Here’s the trick: you want the hormones intact until growth to mature size is finished, but you don’t want unplanned for pregnancies, either.

Sexual maturity will very likely come before bone growth is finished. You’ve heard of teen brides, right?

You’re the Chaperone!

Once more, we’re left with messy old biology to deal with. Never one size fits all, nor simple black and white decision making, living beings are complicated!

They are wired biologically to reproduce, you might say.

While it’s ideal to let your female’s first heat (or two or three) go by before you neuter, you also don’t want the surprise of pregnancy!

You have to be prepared for it and protect her from getting bred.

Doggy diapers can help, but ultimately, determined males can get through about any barrier except one: YOU.

If you have a male, it’s easier: don’t let him wander unattended. If he needs to go out after your bedtime, that either needs to be in a well fenced area, or you need to be there with him, leashing him so he’s not getting a whiff of biology from the female a mile away that sets him on a course to breed her.

I’m seeing more unneutered pets in my practice now, several of them up in years.

I’ve cured a pyometra or two and am confident any practiced homeopathic vet can do this as well.

If I were to shop for a dog at this stage of my life, it’d be a naturally raised intact male, and I’d keep him that way.

Will you choose to neuter or not? And if so, when? Hopefully you’ve now got more information to help you make these decisions.

1Slauterbeck, et al “Canine Ovariohysterectomy and Orchiectomy Increases the Prevalence of ACL Injury” Clinical Orthopaedics and Related Research 429 (301): 5