FDA Approves Canine Sterilization Drug

The only FDA-approved nonsurgical sterilization drug for male dogs is now available to U.S. veterinarians.

Mixed breed dogZeuterin, manufactured by Ark Sciences Inc, offers new hope for low-cost spay and neuter and provides an alternative to traditional, surgical procedures.

The use of Zeuterin does not involve traditional neutering—the surgical removal of a dog’s testicles. Instead, Zeuterin is injected without general anesthesia directly into each testicle using a fine needle. Sperm production ends within one to three days, and the testes ultimately shrink, the manufacturer states.

The drug can be used on male dogs ages 3 to 10 months and may be delivered under mild sedation.

“It’s a simple, one-time procedure that takes only minutes,” says celebrity veterinarian Dr. Marty Becker, who attended the product launch Monday at the Western Veterinary Conference in Las Vegas. “It is such an improvement over traditional castration that shelter operators and veterinarians are embracing it.”

Becker reports that Zeuterin is the first veterinary product he has endorsed.

A similar drug, Neutersol, was distributed by Addison Labs beginning in 2003 but fell out of favor by 2005 over training issues and side effects such as a high rate of testes inflammation.

Ark Sciences acquired the rights to Neutersol and then worked with a contract facility to earn FDA approval while also rebranding the drug and training veterinarians.

An FDA clinical trial found Zeuterin to be safe, with a sterility rate of 99.6 percent. Minor reactions, such as testicular swelling and pain, were observed in 6 percent of the dogs within a week after injection. Adverse reactions may include vomiting, loss of appetite and lethargy, the manufacturer reports. While  Zeuterin cuts testosterone levels by approximately half, according to the company, sterilizing a dog with Zeuterin may not eliminate roaming, aggression and other behaviors commonly absent in castrated dogs.

Ark Sciences initially is focusing on the drug’s mass use through animal shelters and spay/neuter clinics. The company also is conducting online and hands-on training to certify more veterinarians in the precise administration of Zeuterin—from measuring the testicles to injecting the drug. 

The SPCA of Central Florida this month announced free Zeuterin injections for 100 dogs at its Orlando and Sanford veterinary clinics. After the first 100 dogs, the SPCA clinics plan to offer Zeuterin sterilizations for $50.

“Having an injection available to sterilize male dogs, as opposed to traditional surgery, is truly revolutionary,” said Rebecca Rhoades, DVM, a certified animal welfare administrator and medical director of SPCA of Central Florida. “Increased efficiencies also allow us to sterilize many more male dogs with this procedure.”

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