UF researchers test cat sterilization vaccines

Gainesville, Fla.-Immunocontraceptive researchers at University of Florida (UF) are closing in on creating nonsurgical, long-lasting feline contraceptives as tools for population control.

The market: roughly 70 million feral and free-roaming cats.

In collaboration with the U.S. Department of Agriculture's National Wildlife Research Center, UF assistant professor Dr. Julie Levy heads up work on what she says will amount to a new approach to animal control. Contraceptives are the future treatment for uncontrolled reproduction of feral or homeless cats and a likely solution to overpopulation, she says.

"In the past, we've relied on destroying unwanted cats," says Levy, a longtime advocate of trap-neuter-release programs. "Vaccine contraceptives offer a solution that's safe and effective. It's easy for lay people in the field to go out and vaccinate cats."

GnRH

At the core of the new vaccines is a gonadotropin-releasing hormone known as GnRH. USDA researchers report that a single dose of a trial vaccine inhibits GnRH activity for an extended time period, decreasing estrogen and testosterone levels. The vaccine has been tested in several species of "pest" wildlife, including deer, bison, rabbits and rats. The next phase is feral cats.

Encouraging results from a small pilot study of GnRH's effectiveness on male cats has led Morris Animal Foundation to award UF $193,858 to evaluate a single-dose GnRH vaccine in female cats over a two-year period. Immunized cats will be compared to placebo-treated controls by monitoring estrous cycling, serum hormone concentrations and fecundity in a breeding trial, Levy says.

"We just started the study in females, but the vaccine for male cats is very promising," she says. "I'm really excited about it."

Presenting ideas

Results from Levy's work involving the vaccine's effects on male cats will be presented in June at the Second International Symposium on Nonsurgical Contraceptive Methods for Pet Population Control at Beaver Run Resort in Breckenridge, Colo.

Scientific sessions will be conducted to address state-of-the-art information on contraceptive drugs and vaccines, as well as regulation, funding and marketing of contraceptive products.

They are the next step toward addressing overpopulation by eliminating the need for expensive, labor-intensive surgical sterilization, Levy says.

"Contraceptives offer real evidence to a new means of animal control," she says. "They save time and money, but most importantly, they save animal lives. Destruction of animals should truly be a last resort."