“We can just inject this zinc compound into his testicles, and voilà, no more sperm production! Neutering without the knife!”
A reader asked that I weigh in on Zeuterin, the injectable castration agent made from zinc gluconate. It’s made and marketed by Ark Sciences.
Kind of a cool play on words, you’ve got to admit: Zinc + neuterin’ = Zeuterin. Will it become a new verb? “I took Fritz in to get zeutered yesterday. He’s pretty swollen and sore today.”
Here’s how an injection sterilizes a male dog or cat.
The zinc solution is injected into the body of each testicle. Only those who’ve taken the company’s training can do this, and so far, that’s only veterinarians. The injection is made via a very fine needle, while the dog is sedated but usually awake. Some are not even sedated.
Once inside the testicle, the chemical spreads throughout the gland, creating inflammation and killing sperm. The inflammation is such that the testicles swell for several days, and scar tissue is laid down as a healing response to the chemical insult. This scar tissue effectively closes the tubules that are necessary for sperm maturation and delivery.
No tubules, no sperm production. And zinc is toxic to existing sperm cells, so they die. Chemical neutering is accomplished within minutes and is permanent.
Is It Worth it To Neuter Male Animals?
That ought to be your first question before considering chemical vs. surgical procedures.
As I pointed out earlier, the incidence of several diseases increases after neutering, including hypothyroidism, several kinds of cancer, obesity, and multiple orthopedic problems, including cruciate ligament rupture.
In addition, there’s evidence that neutered (and spayed) animals are significantly more likely to have vaccination adverse events in the first few days post-vaccination. [1. Moore GE, Guptill LF, Ward MP, Glickman NW, Faunt KF, Lewis HB, Glickman LT. Adverse events diagnosed within three days of vaccine administration in dogs. JAVMA Vol 227, No 7, Oct 1, 2005]
Odds are, neutered males will never be a significant birth control measure if animal overpopulation is a concern of yours. A female in heat will draw the unneutered male via her powerful pheromones, even if a population of males is somehow 90% neutered.
Known Side Effects
Zinc gluconate is aggressively irritating to tissue, which is why all the scar tissue forms in the injected testicle. If some of the solution leaks during delivery, scrotal ulcers result, and if enough leaks, a full on surgery may be necessary to remove the scrotum as well as the testicles.
The word “necrotizing” appears in the literature associated with this drug. If it leaks during the procedure, healthy tissue the zinc solution contacts dies. Necrosis is tissue death, and it’s not pretty. The fix is a bigger surgery than a simple neuter would have been.
Ouch! No, Probably Not
Yep, some of these dogs hurt after injection, as you might imagine. The clinical trial data showed a low percentage of this, but there was crying, licking, and general discomfort.
Trial dogs for FDA approval numbered 270, and post injection pain occurred in 17 of them, mostly within the first two days of the injection.
From the company’s literature:
While adverse reactions requiring medical treatment occurred in only 1.1% of the dogs, there were minor reactions observed in 6.3% of dogs during the FDA study. Local reactions included testicular swelling (normal reaction to the injection), pain (dogs may resist sitting or may sit with both hind legs open), biting and licking at the scrotum, swelling of the prepuce and irritation, dermatitis, ulceration, infection, dryness or bruising of the scrotum. Systemic reactions included an increase in the white blood cell count, vomiting, anorexia (loss of appetite), lethargy (tiredness or abnormal attitude), and diarrhea.”
In defense of these findings, odds are, if the technique is done properly (very fine needle, very slow injection into the testicles), this will be a painless procedure. Why?
Nature, in her infinite wisdom, has put different pain receptors in various areas of the body. The testicles, much like the intestines, feel stretching, especially sudden stretching, as painful (think gas pains in the belly here).
As my physiology professor pointed out, a match held under a loop of intestine wouldn’t cause pain. Those pain receptors are in the skin, where they act to keep us away from fire.
Similarly, a testicle has pain sensors for crushing injury or sudden expansion, but not for a chemical “burn,” which is essentially what this drug produces. Likely not to hurt, if (a big “if”) the vet is careful in the injection.
Possible Advantage Over Surgery: Testosterone
One upside of “zeutering” over neutering is that the production of testosterone is not shut down completely. Somehow, the cells of Leydig, responsible for this hormone’s production, are left intact after the injection. Because there’s no longer a chemical signal for more testosterone production by developing sperm cells, the overall production of testosterone drops by about 50%.
Testosterone loss is complete in surgical neutering. It’s like throwing a switch when the surgeon removes gonads. “Instant menopause” for the females, and as one wise crack commenter on Quora called it, “instant man-o-paws” for the males. As I mention in the fuller page on neutering, loss of these hormones is a significant one to the animal and can set them up for ill health.
So, keeping some testosterone in the male is a good thing. One protective role of testosterone is a reduction in prostate cancer in dogs.
Provings in Homeopathy
All the substances used in homeopathy have undergone what are known as “provings.” This is where human volunteers, often doctors, take repeated doses of a remedy to see if it elicits symptoms.
The first known proving and the one that launched homeopathy was Dr. Samuel Hahnemann’s self experiment of taking Peruvian bark, Cinchona. This was the crude source of quinine, the cure for intermittent fever or malaria. Amazingly, in his healthy body appeared symptoms of intermittent fever, quite similar to those experienced by malaria sufferers.
He surmised that substances that are capable of producing symptoms are also capable of curing diseases that produce those same symptoms, and homeopathy was born in 1790.
Zinc: Depressed and Fagged Out
If you look up zincum metallicum in your materia medica, you’ll see a pretty dark picture that’s come from either
- people poisoned with excess zinc,
- provings dating back to Hahnemann,
- or those cured of illness with a homeopathic prescription of zinc
The word “fag” comes: worn out, depressed in function, both physically and mentally. “Marked anemia and profound prostration.” Weakness, restlessness. Convulsive twitching or jerking, worse at night, during sleep (hmm, I see this in a lot of my patients, and interestingly, it goes away when they become cured after proper homeopathic treatment). In big bold print (meaning it was common to many of the sufferers in a zinc state of illness), DEFECTIVE VITALITY.
My own homeopath, perhaps more sensitive to zinc than most, was given zinc lozenges by a friend, and told of the deep depression it put her in, “I wanted to jump off a bridge and end it all!” From the materia medica, “Thinks calmly of death.”
So, zinc is a chemical I’d not want injected into my body, certainly, nor into my patients’ bodies.
Zeuter Your Animal? Nah.
In sum, I don’t see chemical castration as a means to more vital animals. Current long term studies are only 40 dogs, tracked informally for over two years (the maker is quick to point out, “fourteen in human years.”). Not too impressive.
The healthiest, most vital guys in my practice still have their testicles (or ovaries), are fed balanced raw food, are minimally vaccinated, and stay away from toxic pesticides for fleas and heartworm prevention.
Their owners are responsible people. They see to it that males don’t breed and females don’t get pregnant by knowing their animals’ whereabouts and exercising close supervision when they go out.
I suspect shelters who are bent on neutering will find more use for this drug than the average pet owner.
OMG. This Really Exists??
Just for fun, before we part ways this time, in my research for this article, I stumbled across something that left me dumbfounded: Neuticals.
Yes, if you don’t want it to look like your neutered male is, erm, lacking in any way, your surgeon can now implant artificial testicles after he’s done! With the real look and feel of a full scrotum, no one ever need know that your guy isn’t packing any more.
The site actually frames their sales pitch partly around how your dog would feel better, sporting a pair of falsies in his scrotum when he walks down the street! Really?
Amazing. Really speaks to the society we’ve become, where appearances have become so important. Epitomized by Kim Kardashian, featured prominently on the Neuticals website, hanging out of her blouse with her dog Rocky, who’s sporting the latest in surgical technology: phony nuts.
Have you thought about using zinc to neuter a male in your life? Oh, maybe I should rephrase that, in case you and your husband are at odds at the moment. Have you considered using chemical castration for an animal in your pack? Let us know in the comments.
And, if you’ve used Neuticals, well, odds are you’re not reading this but are planning your next bust enhancement or tummy tuck. Probably nothing of interest to you on this site.