Estrus Cycles in Cats
When does a female cat have her first estrus cycle?
Cats will have their first estrus cycle, or 'heat' when they reach puberty. On average, puberty or sexual maturity first occurs in cats at about 6 months of age, but this can vary slightly by time of year.
How often does a female cat come into heat?
Cats are "seasonally polyestrus", which means that they have multiple estrus cycles during the breeding season. The breeding season for cats will vary according to geographic and environmental factors such as temperature and the number of daylight hours. In the Northern Hemisphere, female cats usually cycle from January until the late fall. Cats that live in more tropical regions or that mainly live indoors may cycle all year round.
How long does estrus last?
Each heat generally lasts several days - it can be as short as 1 day or as long as 7 days. If the queen is not mated during estrus, she will "go out of heat" for a short period of time, usually 1-2 weeks. Thus, the average complete estrus cycle of a cat is 1-3 weeks.
What are the signs of estrus?
It is not common to observe vaginal bleeding from a cat in heat. The most notable signs of estrus in cats are behavioral. Most cats become very affectionate, even demanding; they persistently rub against people or objects such as furniture, rubbing against their owners and constantly demanding attention. They roll on the floor. When stroked along the back or spine, they raise their rear quarters into the air and tread with the back legs. They also become very vocal. These behavior changes often become annoying to owners, and sometimes owners think their cat has some unusual illness.
Some female cats will urinate more frequently or may even spray urine on vertical objects ("marking") when they are in heat. The urine contains both pheromones and hormones, both of which act as signals of her reproductive status to other cats. This is the reason that queens in heat attract intact male cats. In some cases, this may be the first indication that a young cat has reached puberty.
Tomcats that have never been seen before in the yard or neighborhood will appear and may attempt to enter the house to mate with the female, or may spray your house with urine to mark 'their territory'.
At what stage of the estrus cycle is the cat able to get pregnant?
Cats are "induced ovulators", which means that the act of breeding stimulates or induces ovulation or the release of eggs from the ovaries. Therefore the queen can be bred at any time during the active stage of estrus or heat. Most females require 3-4 matings within a 24 hour period for ovulation to occur. It only takes a minute or two for cats to mate, and cats may mate multiple times in a short period of time. Queens may mate with several different tomcats during this time, so it is possible that a litter of kittens may have several different fathers. Once ovulation has occurred, the queen will go out of heat within a day or two.
How long does pregnancy last in a cat?
Pregnancy lasts approximately 9 weeks (63 days) in the cat. However, it is not possible to detect pregnancy during the first 3 weeks. An experienced veterinarian may be able to palpate or feel the fetuses in the uterus of a relaxed cat, as the optimal time for pregnancy palpation is about 28-32 days of pregnancy. Ultrasonic pregnancy diagnosis can be performed any time after about 25 days of pregnancy. At 6 weeks of pregnancy, the fetal skeletons begin to become calcified and pregnancy can be confirmed by means of radiographs (x-rays) after this time.
How can I prevent my cat from becoming pregnant?
The best way to prevent your cat from becoming pregnant is to have her surgically sterilized (an ovariohysterectomy or 'spay' operation) before she has her first estrus cycle. Since it can be difficult to predict when this first cycle will occur, most veterinarians recommend performing an ovariohysterectomy before the cat is 6-7 months of age.
Should I let my cat have an estrus cycle or a litter of kittens before spaying her?
There are no valid reasons for letting a cat have an estrus cycle or have a litter of kittens before being spayed. Cats can become pregnant on their very first estrus cycle, increasing the chance that an accidental breeding may occur. Cats are indiscriminant, so a brother cat may breed with its sister, a father may breed with his daughter, and a son may breed with his mother.
A common myth is that female cats will become more friendly and sociable if they are allowed to have a litter of kittens. This is not true, and only serves to contribute further to the cat overpopulation.