Researchers recently published the results of a small study in Nature Communications describing how a single shot of a gene therapy prevented pregnancy in cats for at least two years. Researchers analyzed 15,220 freeze-dried fecal samples for estrogen and progesterone levels and examined 1,200 hours of video of mating behavior.
Source: The New York Times, June 6, 2023. Link. The contraceptive shot delivers a gene that enters muscle cells, enabling them to pump out a substance called anti-Müllerian hormone, or AMH, which interferes with the development of egg follicles in the ovaries. Researchers cautioned that much more research would be needed to test the preliminary findings.