Heat (Estrus) Cycle in Cats

Queens vary in the age at which they first go into heat. Some breeds (such as the Siamese) may have their first heat as early as 5 months. Others, particularly the longhaired breeds such as Persians, are not sexually mature until 10 months or older.

Cats are seasonally polyestrous. This means they will have repeated heat cycles over a year unless they are bred, and the heat cycles are influenced by the seasons. The mating season in cats is determined by a number of factors, including the length of daylight, environmental temperature, and the presence of other cats.

When there are 12 hours of daylight and other conditions are optimal, the hormonal system is activated, and the queen begins the estrus cycle. The mating season of cats in the northern hemisphere is from March to September. Cats in the southern hemisphere cycle from October to March.

Throughout the breeding season, queens go into and out of heat several times but do not always display estrous behavior at regular intervals. Often they exhibit continuous heat cycles in early spring (averaging 14 to 21 days from the beginning of one cycle to the beginning of the next), followed in late spring by cycles that are further apart. Each queen establishes her own normal rhythm.

Since cats are considered to be primarily induced ovulators (the physical act of mating causes them to ovulate), a cat will continue to cycle unless she is bred or the daylight factor takes over.

Proestrus

This stage of heat is the first, lasting from one to two days. You may notice that the vulva enlarges slightly and appears somewhat moist, but this usually is not apparent. The queen shows increased appetite and restlessness, utters short low calls, and displays more than usual affection for her owners.

At this time, she begins to attract toms-but refuses to mate. She may urine mark around the house. Proestrus has been described as a period of courtship during which exposure to the male acts as a hormonal stimulus that brings on full heat. This belief stems from the observation that in feral cat colonies, where male companionship is common, the conception rate is higher than in catteries, where courtship is less spontaneous.

If you do not want your queen to become pregnant, take steps at the first sign of proestrus to prevent unwanted pregnancy.

Estrus

The second stage is the period of sexual receptivity. It is what breeders refer to as heat and lasts four to six days. The queen begins to make more noise and her meows are louder and more frequent-eventually becoming almost constant. There is an obvious change in her behavior: She becomes much more affectionate toward people, weaves in and out of their legs, rubs against them, shakes her pelvis, and rolls about on the floor. If picked up when rolling, she may grab at your arm or even bite.

As the urge to mate becomes pronounced, her cries become alarming-sounding like those of an animal in pain. This call attracts toms from near and far.

Young cats having their first heat have been described by unknowing owners as “rabid,” due to the dramatic changes in behavior. It is at this time that many families decide spaying is a good option.

To determine if your queen is receptive to mating, hold her by the scruff of the neck and stroke her down the back toward the base of her tail. If she is in estrus, she will raise her hindquarters, move her tail to the side, and tread up and down with her hind feet.

This estrus period generally lasts 4 to 10 days.