If you are not looking forward to the pitter-patter of little paws, there is a simple solution: Neuter or spay your pet. For cats, the most reliable and effective method for birth control is the removal of the reproductive organs.

For some people, however, the procedure is too permanent. They may want their pet to breed some time in the future, and are looking for a way to suppress the sex drive. Two medications – progestin and mibolerone – have been shown to suppress the reproductive drive, but they are only effective in the female. So far, there is no medication that can suppress the libido in male cats.

Progestins

Progesterone-type medication, such as megestrol acetate, medroxyprogesterone acetate and proligestone, have been used to suppress estrus (heat) in cats. In order to be effective, the medication must be given at a specific time during the heat cycle. The dose of the medication varies on when it is given related to the heat cycle. These medications usually do not affect future heat cycles and the ability to become pregnant.

Currently, there is an implant (Norplant®) being tested and is showing some promise in suppressing estrus in cats.

However, these medications carry increased risk of cystic endometrial hyperplasia, uterine infections and mammary tumors. Diabetes, adrenal gland dysfunction and hair loss have also occurred in pets that have been given progestins.

Mibolerone

Mibolerone is an androgen (testosterone-type drug) that has been used in cats to suppress estrus. The medication is usually started 30 days before the onset of estrus.

As with progestins, there are adverse effects associated with mibolerone. Thyroid disorders and fatal liver disease have occurred in cats.

Due to the potential side effects, use of these medications to suppress estrus in cats is not recommended. Discuss the potential risks and benefits with your veterinarian.