Suppression of the Heat Cycle in Cats

The feline heat cycle, formally known as estrus, occurs initially between the ages of 5 months and 1 year. It lasts between a week and 10 days, then repeats itself every 2 to 3 weeks during the typical breeding season, from January to August. Kitty's behavior changes considerably when she's in heat, so your normally friendly, well-mannered cat can turn into a constant nuisance. The only thing she has on her little feline mind is finding a male cat.

Marketed under the name Ovaban, megestrol acetate contains progesterones that suppress estrus if given to the cat during the proper time in the heat cycle. Your vet can prescribe this medication for your cat, but it's not a good idea for long-term use. Cats receiving Ovaban for long periods are at higher risk for breast and uterine cancer, as well as diabetes or liver problems. Side effects also include diarrhea and vomiting.

Medroxyprogesterone, better known under the brand name Depo-Provera, is a birth control drug approved for use in women but not felines by the U.S. Food and Drug Administration. Vets can use it off-label for dogs and cats. It's used more often to control inappropriate elimination in cats than as birth control, but an injection keeps Kitty from getting pregnant. However, it also can cause diabetes or uterine cancer.

In certain countries, other nonsurgical methods of suppressing estrus and subsequent pregnancy are available. According to DVM 360, these include the controlled-release implants Suprelorin and Gonzalon, both available in Europe. These drugs appear to be safe and effective in female cats. In the United States, the implant Norplant is undergoing testing and might be available soon for veterinarians.

A non-pharmaceutical method of suppressing the heat cycle focuses on triggering ovulation in the cat, but requires getting more up close and personal with Kitty than you might feel comfortable doing. Cat breeders refer to the practice as sham breeding. The technique involves putting a cotton swab or similar item into Kitty's vagina, allowing it to rub on her cervix. This fools her body into thinking she's had intercourse (do you think it really fools the cat?) and ovulation occurs, ending estrus. Another method involves exposing the female to a male that has undergone a vasectomy, but leave this one to knowledgeable professional Always consult an experienced veterinarian regarding the health and treatment of your pet.