Scientists develop new technique to sterilize cats – 06/08/2023 – Science

Scientists develop new technique to sterilize cats – 06/08/2023 – Science


Researchers in the United States have developed a technique for sterilizing cats without the need for surgery. The study, published on Tuesday (6) in the journal Nature Communications, shows that it is possible to prevent pregnancy in these animals using gene therapy.

In the article, 21 scientists from the Cincinnati Zoo, Harvard Medical School and the University of Massachusetts say that sterilization occurred by increasing levels of anti-Müllerian hormone (AMH, in English), produced by the ovaries of females of different species .

The group began studying AMH years ago and, in 2017, published an article showing the contraceptive potential of the hormone in rodents. Since then, with the support of dog and cat protection foundations, researchers have turned their attention to felines.

According to scientists, 80% of the world’s cat population, estimated at 600 million, live free, and although castration is the usual control practice, there is a need for more efficient, safe and cost-effective contraceptive alternatives.

“Surgical sterilization [castração] It’s a difficult model to achieve on a large scale because the surgery requires general anesthesia, a properly equipped operating room, and more veterinarians than currently exist,” researcher Bill Swanson said in an interview released by the Cincinnati Zoo.

To increase AMH levels, the team used a viral vector with a modified version of the gene responsible for expressing the hormone in cats.

“A single injection of the gene therapy vector caused the cat’s muscles to produce AMH, which is normally produced only in the ovaries, and raised the overall level of AMH by about 100-fold,” commented David Pépin, a professor at Harvard, in a note. and also author of the article.

The impact of the therapy was evaluated from the observation of nine cats: three from the control group and six that received the injection with two different doses.

Twice, the females were paired with a male over the course of four months, and the interactions were monitored by video.

In the first test, carried out between October 2019 and February 2020, the three females in the control group became pregnant, giving rise to ten pups, while none of the females in the other groups became pregnant.

In the second experiment, conducted between October 2020 and February 2021, the three untreated cats again gave birth to 11 kittens, while the treated cats did not get pregnant.

The females continued to be monitored and are now available for adoption by residents in the Cincinnati area, where they will continue to undergo health assessments.

According to the scientists, the increased level of AMH stopped the development of ovarian follicles and ovulation in females, but did not affect important hormones such as estrogen, nor did it cause adverse effects.

The researchers highlighted, however, that more studies are needed, with a larger number of cats, to evaluate the contraceptive effect of the treatment. They also recalled that gene therapy is still recent and that there is no structure for producing doses in sufficient quantity to sterilize millions of animals.

“Our goal is to show that permanent, safe and effective contraception in pets can be achieved using gene therapy,” said Pépin. “We hope that, as the capacity to manufacture viral vectors increases with the popularization of gene therapy in humans, it will become feasible to offer this form of contraception to control populations of abandoned cats.”



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