A new study by researchers at the Cincinnati Zoo & Botanical Garden and Massachusetts General Hospital Lindner Center for Conservation and Research of Endangered Wildlife, or CREW, and the Horae Gene Therapy Center shows birth control for domestic cats may be on the horizon.
The research, which can be found in the latest issue of “Nature Communications,” showed that a single dose of Anti-Müllerian Hormone (AMH) gene therapy can induce long-term contraception in female cats. Researchers estimate that there are between 30 million and 80 million free-roaming cats in the United States.
The study was paid for by the Joanie Bernard Foundation and The Michelson Found Animals Foundation, and demonstrates the efficacy of a non-surgical alternative to spaying domestic cats, researchers said.
Currently, there are no contraceptives capable of producing permanent sterilization in companion animals. Spaying, the surgical removal of the ovaries and uterus, is the most widely used strategy to control unwanted reproduction in female cats.
“The trap, neuter [spay], return model is difficult to achieve on a large scale because surgery requires general anesthesia, an adequately equipped surgical facility, and more veterinarians than are currently available,” said senior author and CREW’s Director of Animal Research, Dr. Bill Swanson. Six female cats at CREW were treated with AMH gene therapy and three untreated females served as controls.
A single injection of the treatment caused the cats’ muscle cells to produce AMH (which is normally only produced in the ovaries) and raised the overall level of AMH about 100 times higher. Two, 4-month-long breeding trials were performed one and two years post-treatment to test the efficacy of the AMH gene therapy. “Evidence for the effectiveness of this treatment is strong. All of the control (non-treated) cats produced kittens, but none of the cats treated with the gene therapy became pregnant,” said Dr. Lindsey Vansandt, lead author of the paper and Director of CREW’s Imperiled Cat Signature Project.
The treated cats have been monitored for more than three years to assess the safety of the treatment, including regular physical exams, abdominal ultrasounds, and bloodwork. There were no adverse effects observed in any of the treated cats, demonstrating that at the doses tested, the gene therapy was safe and well tolerated.
It’s not just cats that stand to benefit from this breakthrough. Cats are prolific hunters and their outdoor presence can have devasting consequences for wildlife populations, including North American Songbirds. “Cat predation is a major source of mortality in wild birds. Outdoor cats also contribute indirectly through fear, resource competition, and disease transmission,” said Jenny Gainer, Curator of Birds & African Animals at Cincinnati Zoo & Botanical Garden. The Cincinnati Zoo serves as a program partner to Saving Animals From Extinction North American Songbird (SAFE NAS). The goal of SAFE NAS is to reduce the threats to songbirds and secure sustainable wild populations. “Controlling and reducing the population of free-roaming cats will make a major difference for declining songbird populations.”