Cat Pregnancy and Breeding
Male (tom) and female (queen) cats usually reach puberty between six and twelve months of age, although some are not mature until fifteen months. The actual onset of sexual maturity and the time of first breeding vary greatly with the individual cat because these are influenced by many factors; among them are day length, nutrition, characteristics of the breed, and “psychological” maturity.
(Some females have had their first estrus cycle as early as four months or as late as twenty-one months.) In general, male cats mature physically and breed later than female cats. Although a tomcat may be able to produce sperm and copulate as early as four or five months of age, the actual time he first breeds is dependent on attaining a minimum body weight (usually 7 to 8 pounds, 3.3 to 3.6 kg) and on many social factors not associated with physical maturity. A male cat not yet “psychologically mature” and secure in his social position may not breed in spite of the physical ability to do so.
Queens undergo a cyclical physiological rhythm of reproductive function called the estrous cycle. This cycle is divided into four stages: anestrus, proestrus, estrus, and diestrus (formerly called metestrus). Of the four stages, however, only two, anestrus and estrus, are easily differentiated without laboratory tests.
During anestrus the ovaries are quiescent. This period usually lasts three to four months and usually occurs during the fall and early winter (September or October until January or February in the Northern Hemisphere). It may, however, occur any time of the year. The anestrous state can be artifically induced by the ovariohysterectomy or “spaying” operation. Anestrus is followed by proestrus, estrus, and diestrus, which occur sequentially and repeatedly during the spring and summer months.
During this period of active sexual cycling (seasonal polyestrus) breeding occurs. The estrus or “heat” period, during which the queen is sexually receptive and breeding will occur, is usually marked by an obvious change of behavior and voice.
SIGNS OF HEAT
The meow becomes lower and very frequent (calling), and the cat usually becomes much more affectionate toward humans, rubbing against them (or against inanimate objects) and rolling. Occasionally the estrus female will lose her appetite or spray urine.
Sometimes you may notice increased size of the vulva, but this is extremely variable and is not a reliable sign of heat. If grasped at the nape of the neck with one hand and stroked along the back or genital area with the other, female cats in estrus usually elevate their hindquarters, move their tails to one side, and tread (step up and down) with the hindlegs. These same postures occur when a queen accepts a tom for breeding.
The changes associated with estrus are most easily detected in queens who are kept indoors and not allowed to breed, since the signs may persist up to twenty days (average six to ten days) in the absence of breeding. Cats with free access to the outdoors or to a tom may pass into and out of heat before you recognize it. Cats are induced ovulators (ovulating in response to breeding), and, if bred, signs of estrus soon pass and pregnancy almost always results.
The estrus period in females allowed to breed at will usually has a maximum length of four days. During the breeding season female cats will return to signs of heat about every two or three weeks unless bred or artifically stimulated to ovulate. Remember, however, that these time periods are only averages. Each queen has her own normal cycle that, once established, tends to repeat itself.