A new option to help control feral cat populations may be on the horizon. GonaCon, a vaccine that stimulates the production of antibodies against gonadotropin releasing hormone (GnRH), was recently tested in female cats; the results look promising.

GnRH is normally responsible for stimulating the production and release of sex hormones. When GnRH is inactivated by the antibodies produced in response to this vaccine, the levels of estrogen and progesterone drop in the body and sexual activity ceases as long as sufficient levels of these antibodies remain present. GonaCon has been used to control populations of wild mammals like white-tailed deer, wild horses, bison, elk, ground squirrels, and prairie dogs.

The study was published online in the August 2011 issue of the journal Theriogenology. Researchers at the University of Florida gave fifteen female cats GonaCon and five female cats placebos after which they all were allowed access to an intact male cat. According to the paper’s abstract:

A total of 93% of vaccinated cats remained infertile for the first year following vaccination, whereas 73, 53, and 40% were infertile for 2, 3, and 4 y, respectively. At study termination (5 y after a single GnRH vaccine was administered), four cats (27%) remained infertile.

Meanwhile, the five cats that did not receive the vaccines were all pregnant within one month.

The study does report that five cats developed "non-painful but persistent late-onset granulomatous injection site masses" two years after vaccination, which makes me worry that some cats might develop injection site sarcomas if the vaccine were used in a larger number of cats and follow up continued for a greater length of time. More research is needed to determine whether this would be more than an esoteric concern considering the relatively short lives of feral cats.

GonaCon could be a big step forward in managing feral cat colonies. Traditional population control measures — trapping followed by spay/neuter and release, adoption, and/or euthanasia — are expensive, labor intensive, and controversial. GonaCon won’t eliminate all of these concerns, but it certainly deserves to be looked at it greater detail.

And for an update and some good news…

President Obama signed an executive order on October 31 ordering the Food and Drug Administration (FDA) to take steps to reduce the problem of drug shortages that we spoke about in September. The FDA will take action in three areas:

  • Broadening its reporting of potential drug shortages
  • Accelerating reviews of applications to change production of drugs facing potential shortages
  • Giving the Justice Department more information about possible instances of collusion or price gouging

While President Obama’s executive order is aimed primarily at drug shortages in human medicine, it will benefit our pets as well. Executive orders do not need to be approved by Congress. The President is also supporting Congressional legislation that would require drug manufacturers to notify the FDA six months ahead of a potential shortage. Currently, such notifications are voluntary unless a medically necessary drug is being discontinued.

Dr. Jennifer Coates

Image: Seiji / via Shutterstock