Neutering a male cat is called castration. Male cats are usually neutered between 7 and 9 months of age, before establishing undesirable habits, like spraying urine. Neutering involves the removal of the testicles, the source of sex hormones and sperm cells. The incisions are usually so small that sutures are unnecessary. Generally, the cat is sent home the same day.

Vasectomy is available but rarely used for male cats. "People do ask me about vasectomies in cats for their individual pets, and I always recommend against it for four reasons," says John Hamil, DVM. Vasectomized cats remain territorial and still fight, wander and spray urine, he says.

Vasectomy renders a male cat sterile but does not affect testosterone levels provided the spermatic artery remains intact. Simply put, a vasectomized cat can mate but cannot father kittens.

The procedure has implications for population control in feral cat colonies, says Thomas R. Kendall, DVM, who has done research in this area. The idea is that if dominant males fathering the kittens in a colony or neighborhood are identified and vasectomized, they can continue to mate with females in the colony but not reproduce. Dominant vasectomized males would prevent submissive, intact males from inseminating unspayed females.

"Vasectomy is still a topical issue for feral cat colonies," Kendall says.