The Use of Melatonin as Birth Control in Female Cats

“My girl kept me up all night long! What can I do to stop the howling? I need some sleep!” says the newbie breeder.“Have you tried giving her melatonin?” says the experienced breeder. “It really knocks mine out of heat in a hurry!”

- Lucy Drury

Wander a show hall in the late winter to early spring and you are likely to overhear a similar conversation before very long. Most female cats are not bashful about announcing their availability during estrus (“heat”), and their continual howls can leave a new breeder— or even an experienced one —wondering why they ever though breeding cats was a good idea.

It’s not just the noise that makes frequent heat cycles without a pregnancy a bad idea; they can be detrimental to the prospective queen’s health. Repeated heat cycles can result in the formation of cysts in the lining of the uterus, known as cystic endometrial hyperplasia, which not only can be painful for the cat and reduce fertility, they are also prone to bacterial infection, particular while the cervix is open during the heat cycle and mating. This is known as pyometra, a severe uterine infection that is difficult to treat and can lead to infertility, spontaneous abortion, sterility, and even death in an afflicted queen. Queens with strong heat cycles in show halls can be problematic for both their handler and their neighbors. Their calls and their pheromones are stress-inducing for neighboring cats, particularly adult males, not to mention the girls themselves. At best, the cycling cat and her neighbors may become a little difficult to handle; at worst, someone could get bitten.