2023-06-10 10:00:00
Four of the cats that participated in the experiment/Cincinnati Zoo & Botanical Garden
2023.06.10 Sat posted at 19:00 JST
（ＣＮＮ） There are an estimated 600 million domestic cats in the world. 80% of them are stray or abandoned cats. Spaying and neutering cats can also reduce feral cats, reduce overburdened shelters, and reduce the risk of wild birds and small animals becoming food for cats.
A US research team has developed a new non-surgical method to prevent pregnancies in cats over the long term, and announced it in the scientific journal Nature Communications on the 6th.
Co-author Bill Swanson of the Cincinnati Zoo and Botanical Gardens said the proof-of-concept study was designed to address the problem of overpopulation of cats and dogs and the euthanasia of many of them. “The best way to prevent euthanasia is to eliminate homeless animals,” he said.
The development of a new feline contraceptive method began with the discovery of Harvard Medical School associate professor David Pepin. His team had studied hormones present in follicles, the cell layer surrounding mammalian egg cells, that promote follicle growth. To study its function in detail, the researchers injected the gene that produces this hormone into female mice. In addition to the amount that naturally occurs, it has become a form of additional administration of hormones.
“Surprisingly, the mice stopped most of their ovarian activity and became completely infertile,” Pepin explains.
Pepin’s team learned regarding the Michelson Found Animals Foundation, a non-profit organization that supports the development of non-surgical contraceptives for dogs and cats, and through the foundation, began collaborating with Swanson of the Cincinnati Zoo. rice field.
Michelle, the cat who participated in the experiment/Cincinnati Zoo & Botanical Garden
In addition to cats such as lions, tigers and sand cats, the Cincinnati Zoo was home to regarding 45 domestic cats used for research by the foundation.
“Jack” the cat who participated in the experiment
To study contraceptive methods, the research team selected nine female cats as research subjects and injected the gene for the hormone in question into a virus with mild symptoms into six of them. Because the muscle cells reached by the virus are extremely long-lived, the genes persist for a long time.
Injecting the gene didn’t change the genomes of the cats. “We’re basically putting in a blueprint to make a protein, but it’s not in the animal’s DNA,” Pepin said.
Meanwhile, the gene produced a hormone in the cat’s body that interfered with the development of follicles. If the cells surrounding the egg do not mature, ovulation cannot occur and the cat cannot become pregnant.
The research team observed the hormone levels in the feces and urine of the cats three times a week for two years, and confirmed that the levels of the hormone in question remained high even following more than two years had passed since the injection. bottom. In order to confirm that pregnancy can actually be prevented in this state, the research team sent in two male cats. As a result, all 3 animals that were not injected with the gene became pregnant, while none of the 6 animals in the injected group became pregnant.
The results hold promise for a new method of contraception in cats, but Swanson expects it will take years to get the necessary approvals for veterinarians to prescribe it. “It will be in production, and eventually it will be approved and available, but it won’t happen in a year or two,” he said.
The cats in the study will be looking for foster homes around Cincinnati. New owners should be brought to the zoo once a year to observe changes in hormone levels and any side effects.
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