Brazilian scientists develop method to castrate animals without surgery

RIO DE JANEIRO, BRAZIL – Neutering is a public health measure considered one of the most essential forms of population control for dogs and cats. The measure reduces the reproduction rate, abandonment and transmission of diseases among animals.

To reduce the number of street animals and promote access to spaying and neutering, scientists from the University of Brasilia (UnB) have developed fast and non-surgical spaying and neutering method for dogs and cats.

The studies were conducted by researchers Vanessa Nicolau de Lima, a doctoral student in the Graduate Program in Animal Biology, and Juliana Lis Mendes de Brito, a postdoctoral student in the same program, with support from Capes (Coordination for the Improvement of University Personnel).

In this procedure, which is exclusive to male animals, the animal is anesthetized and receives an injection of tiny iron oxide particles into the testes. Sterilization can then be achieved by applying a magnetic field (magnetohyperthermia) or an LED light (photohyperthermia). In both procedures, the temperature reaches about 45 degrees and does not cause burns to the animals.

In magnetohyperthermia, the external magnetic field is applied in the testicular area, and the injected nanoparticles generate heat only at the application site. The photohyperthermia procedure, on the other hand, involves using an infrared LED so that the nanoparticles convert light into heat and promote sterilization.

According to Juliana, the procedure takes 20 minutes and results in atrophy of the testicle. “We followed 13 animals and reached the end of the experiment with one animal that had remnants of a tissue that we believe is a testis, but it was no longer functional,” Juliana says in a statement.

PUBLIC HEALTH PROBLEM

According to researcher Vanessa de Lima, a single pair of cats can produce about 50,000 offspring in 10 years, including direct and indirect offspring.

“The contingent of dogs and cats living on the streets is a challenge for public managers. It’s a public health issue. This research opens the possibility of being used in public policy,” he affirms.

Although surgical neutering plays an essential role in the population control of dogs and cats, the procedures are not always sufficient or accessible for the high demand in large cities. Experts believe the project can help reduce the public health impact.

The magnetohyperthermia technique used in animal spaying and neutering, coordinated by Professor Carolina Madeira Lucci of the Postgraduate Program in Animal Biology, was patented in 2020.

The development of the new castration method was possible thanks to interdisciplinarity, which brought together knowledge from the fields of biology and physics. Andris Bakuzis, professor at the Physics Department of the Federal University of Goiás (UFG), provided the iron oxide nanoparticles for the study.

According to Bakuzis, the cost of producing the nanoparticles is low and the dose used per animal is small: “You don’t need a very large amount, which is good because it reduces the potential toxicity of the substance, since the amount you actually put in is minimal,” the professor said in a statement.