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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.

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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.


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.

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