CINCINNATI — The Cincinnati Zoo has helped developed a way to spay cats — and tackle cat overpopulation — without having to perform surgery.
The zoo's Center for Conservation and Research of Endangered Wildlife (CREW) teamed up with the Massachusetts General Hospital and Horae Gene Therapy Center to publish findings from a study on effectiveness of a non-surgical alternative to spaying domestic cats.
The study was funded by The Joanie Bernard Foundation and The Michelson Found Animals Foundation.
The study's research found that a single dose of a Anti-Mullerian Hormone (AMH) gene therapy can induce long-term contraception.
The zoo said these findings represent a step toward humanely reducing free-roaming cat populations, as well as eliminating euthanasia of healthy shelter cats.
While exact numbers are unknown, there's an estimated 30 to 80 million free-roaming cats in the U.S., and animal welfare experts have long used spaying as a widely used strategy to reduce that population.
"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 unavailable," said Dr. Bill Swanson, senior author and CREW's director of animal research.
Other than helping with the cat population itself, the zoo said this breakthrough can positively impact other wildlife populations impacted by too many cats.
During research, six cats with CREW were given the single dose of gene therapy, and three other cats were left untreated to use as controls in the study. That dose caused the cats' muscle cells to produce the hormone, which is normally produced in the ovaries, and raise the hormone level roughly 100 times higher.
The scientists then tested two 4-month breeding trials a year after the dose was given and then two years after it was given.
"Evidence for the effectiveness of this treatment is strong," said Dr. Lindsey Vansandt, lead author on the paper and director of CREW's Imperiled Cat Signature Project. "All of the control (non-treated) cats produced kittens, but none of the cats treated with the gene therapy became pregnant."
The treated cats have been monitored for more than three years to assess the safety of the treatment, the zoo said there has been zero adverse side effects.
Gary K. Michelson, founder and co-chair of the Michelson Found Animals Foundation, said the findings are a "major milestone."
"A non-surgical sterilant for community and companion animals is long overdue and will transform animal welfare," Michelson said.
The cats involved in the study were also put up for adoption, and several found forever homes with Cincinnati Zoo staff members and volunteers, including Dr. Swanson himself.
"We are cat lovers, which is one of the reasons we're excited about what this new technology can do to improve the lives of domestic cats," he said.
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