Hormone Injections for Cats in Heat

It's no wonder you want to do something to prevent Kitty from coming into heat, if spaying's not an option. While cats don't bleed when in heat like dogs do, it's pretty obvious when it happens. Kitty might be affectionate to the point of being a nuisance. She'll roll around on the floor, yowling her head off. Going out the door without Kitty coming along is an exercise in fancy footwork. What's worse, this behavior can last a week or more, repeating itself just three weeks later.

Marketed under the name Depo-Provera, this synthetic progesterone hormone is approved by the U.S. Food and Drug Administration for birth control in women, but veterinarians can use it "off-label" for feline and canine patients. It's also used not just to suppress heat, or estrus, but to aid cats with certain behavioral issues, such as inappropriate urination. During pregnancy, progesterone protects the fetuses and helps the placenta grow. After receiving the injection, your cat's body believes it is pregnant, so estrus doesn't occur. Kitty will probably receive monthly injections to suppress her estrus cycle. If it's given for behavior modification, she might receive a shot every three to four months.

Think carefully and discuss options with your vet if you decide to give Kitty Depo-Provera injections. It's a powerful drug with potentially serious side effects. Depo-Provera can't be given to cats diagnosed with diabetes, but may also cause diabetes in some felines. It can also cause mammary—or breast—cancer, as well as uterine infections. A bad uterine infection might leave you no option but to spay Kitty. She might also gain weight while on the drug, because it can cause an appetite increase at the same time that it makes cats somewhat lethargic.

Another hormonal option for suppressing estrus systems is megestrol acetate, marketed under the brand name Ovaban. This medication is available in pill form. According to the Merck Veterinary Manual, the dosage for estrus suppression is 5 mg daily for three days, then between 2.5 and 5 mg once a week for up to 10 weeks. If you don't plan to breed Kitty at that point, allow her to have one normal heat before she receives Ovaban again. Ovaban has many of the same risk factors as Depo-Provera.