Answer: All female animals undergo cycles of sexual activity called oestrous cycles. The overall regulation of these is performed by a part of the brain, the hypothalamus, which responds both to changes taking place in the body, such as hormone levels, and to environmental changes, particularly the number of hours of daylight. The hypothalamus has the role of preparing the animal both physically and psychologically for meting, pregnancy and birth and ensuring their successful completion. It does this through its control of the hormonal output of the pituitary glands (at the best of the brain) which is turn affects the release of the sex hormones, oestrogen and progesterone, from the ovaries.
In the male cat (the queen) oestrous cycles recur throughout the breeding seasons which extend from late winter to autumn, (approximately January to September in Britain, North Europe and North America; October to June in Australia and New Zealand). During the late autumn and early winter there is a period of sexual inactivity called anoestrus, lasting on average four months, which is associated mainly with the decreased amount of daylight, and much less with fall in the temperature. Consequently cats kept indoors with artificial lighting may have no such period, or only a very short one, so that their oestrous cycles then occur practically all the year round.
There are generally two or three peaks of sexual receptivity during the year when the cycles are most noticeable; in the northern hemisphere these are early spring and early summer, and sometime in late summer/autumn. At other times sexual receptivity wanes and the cycle are less obvious.
An oestrous cycle beings with a preparatory stage during which the cat is often more affectionate, though restless and unwilling to mate; she paces up and down, often rubbing against the furniture, and she may roll on the floor. Often she urinates more frequently. Unlike in the bitch, there is little obvious swelling of the vulva and usually no vaginal discharge at this time. Then after one to three days she enters the stage of oestrus, or sexual receptivity, during which she will be prepared to mate.
The previous signs are intensified; the cat roll on the floor emitting a characteristic howling cry known as the ‘call’, which is particularly raucous in the Siamese. For this reason oestrus is often popularly referred to as ‘calling’, or ‘being on call’. Other euphemisms described the queen as being ‘on heat’ or ‘in season’. This behavior is often so dramatic that owners who have not witnessed it before believe that the cat must be in great pain and seek veterinary attention as a matter of urgency. When stroked the cat adopts the mating posture normally adopted in the presence of tom, with her forelimbs lowered and her hind quarters raised giving a concave curve to the spine. The tail is down to one side, and in this crouching posture she makes treading movements with her his feet. The cat often goes off her food and may spy urine in the house. If confined she will make determined efforts to escape outside. Even if these signs are not sufficiently distinctive for you to notice them, and this may indeed be the case with a cat pregnant for the first time (the maiden queen), the neighbourhood toms will almost certainly know and congregate outside your home.
Unlikely most other mammals, the cat does not release an egg or eggs from the ovaries (the process of ovulation) unless she has been mated. Ovulation takes place twenty-four to thirty six hours after mating and this ensures that the egg(s) will not be discharged until there are sperms already present, so that fertilization in much more likely to take place.
If mating occurs, the signs of oestrus decline within one two to days; if not, they will persist for ten to twelve days. If the female becomes pregnant as a result of mating, no further oestrous cycles will normally occurs, but if mating doesn’t take place oestrous will be followed by a quiescent period lasting seven to twelve days before signs of pro-oestrus appear again, indicating the start of the new cycle. Consequently, oestrus cycles recur at intervals of approximately twenty-one days. Older queens tend to have shorter oestrous cycles.
In about 12% of queens, and those if the Siamese breed in particular, dioestrus appears not to occur, and calling can continue noon-stop for six to ten weeks or more (referred to as nymphomania) which can be very wearing for the owner.
There are no breeding seasons for male cats and they are able to mate all the year around, although in fact they are more active sexually in the spring and much less so during the winter. Undoubtedly this is related to the presence of calling females at those times.
