What is Zeuterin or Chemical Castration/Chemical Neutering?
Chemical neutering (such as with Zeuterin™) is for MALE dogs.
At this time in the USA, female dogs & cats require surgical spaying to make them sterile. Surgical neutering of male dogs and cats does not remove the scrotum, but does remove the testicles that are inside the scrotum.
Chemical neutering of dogs was developed as a way to control large populations of free roaming dogs in areas where surgical neutering is not feasible due to lack of accessibility. The chemical neutering process of Zeuterin™ has been around for over a decade. It is the chemical zinc gluconate neutralized with arginine. It was originally marketed as Neutersol in 2003, but disappeared from the market by 2005 because of too many adverse reactions as a result of improper injection technique. It is currently being marketed as Zeuterin™ with on-line training for veterinarians and vet techs so they can become certified by Ark Sciences to properly administer this chemical.
"Zeuterin™ is currently U.S. FDA approved for dogs 3-10 months old and testicle widths in the range of 10-27mm." Outside the US, Zeuterin™ is known as EsterilSol, and is licensed for dogs 3 months and older. When Zeuterin™ is injected slowly into the center of each testicle, the chemical causes “permanent and irreversible fibrosis in the testicle rendering the dog sterile.” (Quotes source: the Zeuterin™ website.)
Calcium chloride dihydrate in alcohol, “Calchorin”, is also used to chemically neuter male dogs and it yields similar results to Zeuterin™. Spay First has a video on their website that shows a chemical neutering of a dog, which they only recommend for street dogs, not for pet dogs where surgical neutering is affordable and available.
Planned Pethood Taos recommends chemical neutering of pet dogs only in the rare medical cases where surgical neutering is not possible for that dog, or if a dog owner is strongly against surgical neutering of their male dog. Considering the tremendous dog overpopulation problem here and around the world, chemically neutering a dog is better than leaving the dog intact/fertile. However, considering the (1) relative ease and access to free and low-cost surgical neutering for Taos area residents (2) behavioral benefits and (3) lower testicular cancer rates resulting from surgical neutering, surgical castration remains the gold standard for neutering one’s pet dog here.
“Zeuterin™ may or may not eliminate male behavior, such as roaming, marking, aggression, or mounting.” (Quote source: the Zeuterin™ website.)
Chemically neutering a dog will not completely eliminate testosterone from the treated dog. In fact, most dog’s testosterone levels are only marginally reduced. In a recent study using EsterilSol [Zeuterin™], “~ 30% of the chemically sterilized dogs has a reduced testosterone concentration…similar to surgically castrated dogs. Most chemically sterilized dogs, however, showed no long-term changes in blood testosterone concentrations.” Therefore, the hormonal- based behaviors that most pet owners find frustrating are likely to remain.
(Quote source: Vanderstichel, et al., Theriogenology 2015 Apr 1; 83(6):1021-7.)
Chemical castration is not without its own risks. “Some dogs that are Zeutered experience pain, testicular swelling, vomiting, redness and, rarely, ulceration of the scrotal skin.” (Source: the Zeuterin™ website.) In cases with severe ulceration to the testis, complete removal of the scrotum is necessary, requiring full anesthesia from a DEA-licensed veterinarian to perform the surgery. “EsterilSol [Zeuterin™] is an appealing choice for situations when the public is unlikely to opt for surgical castration, since it is FDA approved and its application requires little equipment. The occurrence of severe adverse reactions at unpredictable times after administration, however, emphasizes the need for the provision of long-term monitoring and veterinary care”.
(Quote source: Forzán, et al., Veterinary Pathology 2014, Vol. 51(4) 820-23.)
Anesthesia is not required for chemical neutering, but it does require sedation since a dog must remain still during the injection while the chemical is slowly injected. Ark Sciences, the company that sells Zeuterin™, “recommend[s] a combination of Dexdormitor and Butorphanol”. “Butorphanol (aka Torbugesic) does require a DEA license”.
(Quote source: ArkSciences Customer Relationship Manager.)
Furthermore, if Zeuterin™ is administered by a DEA-licensed veterinarian, your dog can be treated in the safest manner possible if there are complications during or post injection. If Zeuterin™ is administered by a veterinarian without a DEA license or by a vet tech, treatment options for complications are more limited, and may increase the time in which the dog can get the necessary treatment if the dog needs to be transferred to a DEA-licensed veterinarian for follow up care.
Worried your dog will become fat and lazy if surgically or chemically neutered?
The activity level for all dogs reduces as puppies transition into adulthood. Ever notice the middle age pudge for humans? We tend to be less active as adults than we were as children. Most of us cannot consume as many calories as we did as children since we are no longer growing. So adult dogs must reduce calories and continue to exercise (go for walks, etc.), just like adult humans, to prevent weight gain.
Zeuterin™ is not FDA approved for use in cats.
Anyone who has smelled male cat urine would agree that surgical neutering of pet cats is a much better remedy, as surgical neutering gets rid of that overpowering male cat urine odor, as well as reduces roaming and cat fighting. A high-quality, high-volume veterinarian can surgically neuter a male cat in 30 to 60 seconds (cut to close), which is far less time than what is required for chemical neutering. Male cats have an incision made in the skin of the scrotum, and the testicles are removed.
How to get a chemical neuter for your dog: Not currently available.
Chemical neutering is not offered by the Santa Fe Animal Shelter & Humane Society, the Española Valley Humane Society nor any of the local Taos vets because those vets prefer the benefits of surgical neutering.
Zeuterin™ is no longer in production as of 2016 due to lack of profitability for the Zeuterin company.
How to get a surgical spay or neuter for your dog or cat:
Taos area residents have multiple options for free and low-cost spay-neuter. Both the Santa Fe Animal Shelter & Humane as well as the Española Valley Humane have multiple DEA-licensed, high-quality high volume surgical spay-neuter veterinarians. Furthermore, the Salazar Rd. Vet Clinic and the Taos Vet Clinic have DEA-licensed veterinarians who routinely perform surgical spay-neuter on cats and dogs. At this time the Taos Animal Shelter, aka Stray Hearts, does not offer spay-neuter for the public.