New Drug 'Chemspay' Could Sterilize Female Dogs Without Surgery

A new drug could be the non-surgical alternative to spaying female dogs and a major change for animal shelters.

Chemspay is a contraceptive drug that can either be administered orally or through injection, and based on trials significantly reduces the number of eggs in a female dog's ovaries, making them sterile.

The Arizona Republic reports:

Dr. Loretta Mayer was looking for a way to artificially induce menopause in mice so they could be used to study human diseases when she and another scientist developed a drug that they realized also could be used to sterilize female dogs, removing the need for expensive and painful surgery.

The first drug they developed, dubbed "mouseopause," eliminated the eggs in a mouse's ovaries. Mayer looked for ways to adapt the drug for other animals, including "ContraPest" in rats, as an alternative to poison in areas where animal overpopulation is out of control.

"I would really like to see us do things that improve our environment and are compassionate to other beings," Mayer told the Republic. "My passion, without question, is to stop killing animals, however we might do that."

Mayer began testing Chemspay on dogs in 2004 on Arizona's Navajo Reservation when the tribal animal shelter's director asked for her help with their feral and stray dog problem.

"He said to me, 'If you could do for a dog what you do for a mouse, I wouldn't have to kill 400 animals a month," Mayer said. "This technology, if successful, will really have a huge impact on unwanted dog populations."

In Arizona, thousands of dogs and cats are euthanized in overcrowded animal shelters every year. According to the Republic, the Arizona Humane Society performed nearly 20,600 surgical sterilizations on dogs, cats and rabbits in the past year, at a cost of almost $2 million.

Food and Drug Administration approval is still at least six years away, but Mayer hopes to begin FDA trials in Arizona within the next few years.

Chemspay is not the first drug alternative to surgical sterilization: Neutersol, for male dogs, was approved by the FDA but taken off the market in 2005 due to a manufacturing dispute. GonaCon is a contraceptive currently used on deer populations, and is being studied for use in dogs and cats.

Check out this 2009 report in which Mayer discusses the development and use of ContraPest in curbing rat overpopulation in rice fields: