Vaccine Could Help Control Feral Cat Population

UF researchers test a long-acting contraceptive on feral cats.

By Drew Andersen | Posted: September 30, 2011, 3 a.m. EDT

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Orange cat outside
UF researchers say a vaccine is a less expensive, less invasive way to curb feral cat reproduction.
A study performed by University of Florida researchers could aid in the management of feral cat populations.

The researchers found that a single dose of the immunocontraceptive vaccine GonaCon controls fertility over multiple years in adult female cats.

“We’re hoping this research will lead to a nonlethal method of control for feral cat populations that is less expensive, labor-intensive, and invasive than current methods, such as surgical sterilization,” said Julie Levy, DVM, Ph.D., lead researcher and director of the Maddie’s Shelter Medicine Program at UF.

Non-profit veterinary research organization Morris Animal Foundation funded the five-year study, which was published online in August in the scientific journal Theriogenology.

The UF researchers administered single dose vaccinations to 15 female cats and placebos to another five cats. The cats were then allowed access to a breeding male cat. All five placebo females became pregnant within seven to 28 days.

Among the cats treated with GonaCon, 93 percent remained infertile for the first year, 73 percent remained infertile in year two, 53 percent in year three, 40 percent in year four, and 27 percent in year five. Levy said researchers expected the decrease in the vaccine’s efficacy as the cats’ antibodies to the vaccine decreased.

“Although a permanent sterilant would be ideal, a long-acting contraceptive could be an effective tool for managing feral cat populations, especially where surgery is unavailable or impractical,” said Joyce Briggs, president of the Alliance for Contraception in Cats and Dogs, an advocacy group for nonsurgical birth control methods in animals.

Feral cats have recently come under attack as contributors to the spread of rabies. Many wild bird advocates consider feral cats a threat to bird populations, and consider more drastic measures than feral cat sterilization necessary.

Researchers at the USDA Animal and Plant Health Inspection Service National Wildlife Research Center developed GonaCon, and the UF researchers do not have any licensing agreements with the USDA or any commercial interests in the vaccine. The vaccine is registered by the U.S. Environmental Protection Agency for use on female white-tailed deer, and it been effective with other mammal species including feral horses, bison, elk, prairie dogs and ground squirrels.

The vaccine stimulates the production of antibodies that bind to GnRH, a hormone in an animal’s body that signals the production of sex hormones, such as estrogen, progesterone and testosterone. By binding to GnRH, the antibodies reduce the animal’s ability to stimulate the release of these sex hormones. All sexual activity is inhibited, and the animals remain in a non-reproductive state as long as a sufficient level of antibody activity is present.
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Vaccine Could Help Control Feral Cat Population

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Reader Comments

karen    cheektowaga, NY

10/23/2011 11:35:15 PM

Interesting !!!

Shirley    Tucson, AZ

10/21/2011 6:03:21 AM

Interesting discussions here.

Dr. Pierson, CA

10/12/2011 3:14:02 PM

As a vet who has darted about 15 feral cats for spaying and neutering, I will tell you that it is NOT easy to do and requires a special set of circumstances to perform. I do not see this as a viable options in 99.9% of all cases.

It takes about 10 minutes for a cat to fall asleep so you have to be absolutely sure that the cat cannot get anywhere that is inaccessible. The cat does not just drop like a rock once hit with a dart and, believe me, when they are hit hard with a big needle....they can travel a VERY long distance before falling asleep.

You also have to find a vet who has the equipment, the darts, the proper sedatives....the experience/talent to hit a small moving target with SAFE accuracy!!...and the willingness to spend a great deal of time performing the task.

As noted in an earlier comment, I do not see this vaccine as a positive thing. This is coming from a point of view from spending many hours 'in the TNR trenches' trapping cats over the past 15 years.

For the cats that will not get into a conventional wire trap, I have designed a folding drop trap that can be seen at

Kelly    Hamburg, NY

10/12/2011 4:43:08 AM

Having some experience with trapping ferals in our community and how difficult that is, not too mention our feral cat TNVR clinic is always full or not running clinics, I think the vaccine is a good option to keep the population from exploding until the cats can get spayed/nuetered. Further, I recall my horse vet, years ago, had a "dart gun" that she had to use to administer a tranquilizer for one of the difficult and dangerous horses. Sounds crazy, but it would be a possibility. Sometimes one has to think "outside the box" to come up with ideas and solutions.

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