Nonsurgical Contraception - The Pros and Cons for Community Cats

There is no question about it— trap-neuter-return (TNR) saves cats from suffering and dying. Cats who have been TNR’d face far fewer risks to their health than unsterilized, unmanaged community cats. The even more significant effect of TNR is that it prevents community cats from producing kittens, 75 percent of whom probably will die and suffer from painful diseases before reaching six months of age.

When we at ACR drop off a feral cat, secure in the trap, to be fixed at a clinic, our main feelings are of happiness and optimism. We know that in a few days, she will dash out of the trap, back to her outdoor home where she has the greatest chance at living a long, comfortable life. 

A breakthrough contraceptive shot for female cats is showing a lot of promise. The shot uses gene therapy to stop the ovaries from producing eggs and so far, it does not appear to cause any side effects. The positive implications of a single-injection sterilant for female cats go even beyond benefitting sparing the cats from surgery. Females make up around half the outdoor cat population. If they could be sterilized in just minutes at the trapping site and by the trappers,  that would be a huge step forward in ending cat overpopulation. 

There are some practical hurdles and downsides to nonsurgical contraception. The shot is believed to remain effective for about two years, maybe longer. That will be good for pets, and could certainly enable shelters to ensure all female cats are sterilized prior to adoption. However, to be useful for community cats, the sterilization must last for the lifetime of the cat. Community cats who receive basic daily care, as all should, can live well into their teens.  

Another complication may be finding a way to identify cats who have been sterilized. We would need to find a replacement for ear tipping that is painless but also permanent and easy to see. One possible solution, proposed by the Alliance for Contraception in Cats and Dogs (ACC&D) is a tattoo patch, done with microneedles. The tattoos have been tested on a group of 97 dogs and cats and, according to the ACC&D, have not faded within the first three months, which is encouraging. 

TNR pioneer, Dr. Julie Levy, has pointed out that cats sterilized by injection would still be susceptible to mammary and other cancers and diseases of the reproductive system that often occur in cats.* This must be a consideration for all cats, including pets. And, Dr. Levy reminds us, the hormonal behaviors of cats in heat, such as yowling, would also remain an issue. 

Nonsurgical sterilization could be a TNR gamechanger. However, there are significant barriers to its use in community cats. It has taken two decades and teams of scientists to develop an injectable sterilant. If it does become commercially available, the torch must be passed to veterinarians and the TNR community, so that we find a way to make the sterilant work for the cats whom it will benefit the most.
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*Reference: 
Grimm, David. “Hello Kitty, Goodbye Kittens? Gene Therapy Spays Cats Without Surgery.” Science, 6 June 2023, www.science.org/content/article/hello-kitty-goodbye-kittens-gene-therapy-spays-cats-without-surgery.

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