Breeding and Reproduction: male birth control


Castration (removal of the testes) is the traditional method employed for neutering (altering) male cats. Although castration renders a male cat sterile and unable to impregnate a female and is the socially responsible thing to do, the birth control aspect is of minor importance unless other neighborhood males are also neutered. (One roaming tom can impregnate all the unaltered females in a neighborhood.) The prime significance of castration for most owners of male cats is the changes of behavior that follow it.

Breeding, fighting, roaming, and urine spraying are behavioral patterns that are activated when the blood level of testosterone (a hormone secreted by the testes) rises markedly, following sexual maturity. Roaming results in encounters between cats—by nature loners—and fighting often results. The wounds and abscesses that follow are not only extremely stressful for the cat but can also become very expensive when they occur repeatedly and require veterinary treatment.

Urine spraying is a kind of scent-marking behavior associated with territorial identification. Both neutered male and female cats may spray, but this behavior is most characteristic of tomcats. The male who is scent marking backs up to the object to be marked, raises his tail to a 45- to 90-degree angle, and as the tail quivers sprays or squirts a small amount of urine onto the vertical surface of the object. Occasionally squat spraying occurs where the urine is deposited on the ground. Although perfectly normal, this behavior is not acceptable to most cat owners when it is performed around the house.

Tomcat urine has a strong and objectionable odor that, together with the stains left from spraying, can be difficult to get rid of.


Castration before puberty prevents the development of behavioral patterns most often considered objectionable by owners of male cats.

Castration later in life, after roaming, fighting, and/or spraying has developed, often stops objectional behavior within two weeks, although in some instances improvement takes several months. In a few instances (6 to 13%) fighting, roaming, and/or spraying persist and are independent of the age of the cat at castration or time of the onset of behavioral problems.

Castration also helps prevent the development of “stud tail”. And castrated males are generally more affectionate and docile. In other words, a castrated cat is usually a much better pet and companion than his unneutered counterpart.

Castration can be performed by your veterinarian as early as six months of age. Many animal population control advocates encourage the surgical neutering of toms by castration before six months of age. Although this effectively prevents breeding, males neutered at this age do not develop the characteristic secondary physical sex characteristics that distinguish mature male cats (e.g., larger heads and bodies and better defined muscles). Their behavior toward people is not adversely affected by early neutering. Should you desire normal male development and if you will be careful to prevent random impregnation of queens by your pet, castration can be delayed until adulthood or until objectionable behaviors develop.

The surgery is simple and should be inexpensive. A short-acting general anesthetic is usually administered intravenously. The hair is plucked from the scrotum. After disinfection, two incisions are made in the scrotal sac, one over each testicle, and the testes are removed through them after the spermatic duct and the blood supply are interrupted. The incisions are allowed to heal as open wounds. Most veterinarians will send your cat home to recover the same day or within twenty-four hours following surgery.

It is a good idea to examine the castration site for signs of infection and to take your cat’s temperature daily until the castration wounds are healing well. No special care is necessary later except perhaps to watch your cat’s diet. Although castration does not cause a cat to become fat, the lower daily calorie needs of an altered male may result in obesity if you allow free-choice feeding or overfeed him.


Vasectomy, surgical removal of a portion of the vas deferens that conducts the sperm from the testes to the urethra, is rarely performed on male cats. Although vasectomy renders a male cat sterile and unable to impregnate a female, it has no effect on his ability or desire to breed, or on other behavior undesirable in a pet, because it does not remove the source of testosterone—the testes.

A vasectomy may be useful to the owner of a purebred cattery who desires to keep a sexually active but sterile male available to bring queens out of heat. But since it has no effect on fighting, roaming, urine spraying, grooming, or docility, it is not desirable for most house pets. Also, vasectomy is a more difficult, and therefore more expensive, operation than castration.