Merck Manual

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Pet Owner Version

Breeding and Reproduction of Cats


John A. Bukowski

, DVM, MPH, PhD;

Susan Aiello


Reviewed/Revised Jul 2011 | Modified Oct 2022
Topic Resources

Like dogs, cats also have an estrous, or heat, cycle. However, female cats, which are called queens, are induced ovulators. This means that they do not ovulate (pass an egg) unless they are bred. This greatly increases the chances of conception when bred, which is why stray queens often have many kittens per year. The queen can enter her first heat as young as 4 months of age, and she generally has 2 or 3 heat cycles during the breeding season (typically February to October in the northern hemisphere). During heat, the queen is receptive to males and shows characteristic mating behavior. She will roll, rub against objects, knead her back feet, and yowl repeatedly and loudly. This behavior can last 3 to 20 days and can repeat in 10 to 40 days if the queen is not bred. If the queen is bred, the cycle ends as her body prepares for pregnancy.

Multiple kittens

Multiple kittens

Gestation, or pregnancy, lasts about 2 months (60 to 63 days), with an average litter size of about 4 kittens. Queens can be bred by more than one male during a heat period, resulting in kittens from the same litter with different sires. Signs of pregnancy include a large abdomen, increased appetite, and swollen mammary glands that may release milk when squeezed. During the later stages of pregnancy, the queen seeks a nesting area and places bedding in a quiet, secluded spot. Cats that are not pregnant sometimes show these signs of pregnancy during a pseudopregnancy, or false pregnancy. This usually begins at the end of estrus and can last for several months. Your veterinarian can tell you if the pregnancy is real or false.

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