Please read: Update on Feline Contraceptive FeralStat
Oral contraception for cats can be an alternative method of controlling population in the feral cat community.
According to some reports, birth control pills for pets have been around for a good many years. The advantage of pills or injections is that they are a non-surgical procedure. But they must be used with great care and under the supervision of a veterinarian. They are also not 100% effective.
Ovaban (megestrol acetate, similar to progesterone, a hormone) can have some serious side effects such as diabetes, skin disorders, inflammation or cancer of mammary glands, pyometra, danger to adrenal glands, creating Addison Disease-like symptoms.
There is an injectable called Depo-Provera (medrocypogesterone) which is also sometimes used.
Ovaban is used in humans, but is not approved by the FDA for use in animals. However it may be legally prescribed by veterinarians.
Oral contraceptives have been used on horses and raccoons in the wild.
The drugs act so that the cat’s body thinks it is pregnant, eliminating heat cycles. The drugs have been used for behavior problems such as aggression, urine spraying or any unwanted male sexual behaviors. These drugs can also interact with others such as antibiotics and steroids.
The drugs must be used cautiously and only under veterinary supervision.