Non-spayed female cats will go into "heat" or estrus seasonally--typically February through October in the Northern Hemisphere. They may go into heat many times during the season if they are not bred. The period of heat lasts an average of about a week but can vary from three to 14 days. Your cat will exhibit many behaviors during the estrous cycle that you should expect. The only cure for these behaviors is to have the cat spayed.
Five Stages of the Feline Estrous Cycle
A female cat goes through five estrous stages of different lengths:
- Proestrus: Not many signs are seen in the cat for this stage. The female is attractive to the male but unwilling to mate. Length: one to two days.
- Estrus (Heat): This is when the female cat is receptive to the male. External signs such as a swollen vulva are not as observable in the cat as they are in the dog. The main signs are behavioral—loud vocalizing, rolling on the floor, elevating the hindquarters, and possibly a decrease in appetite. Many people have confused the signs of the feline estrus phase as signs of being in pain. Length: three to 14 days (average of one week).
- Interestrus: The period between estruses if the female isn't bred. Length: around nine days on average, but can be anywhere between four and 22 days.
- Diestrus: Period after mating and ovulation (with or without pregnancy). Length: 35 to 40 days without pregnancy. If pregnant, pregnancy lasts on average 60 to 64 days in the cat.
- Anestrus: Period of inactivity (sexual and hormonal) that occurs during low light months.
Facts About Feline Estrus
The first estrus usually occurs between the ages of 6 to 12 months; for some cats as early as 4 months of age, for others not until after 12 months. Cats can get pregnant during their first heat cycle, but this is not advisable as a 6-month old cat is not yet fully grown/mature, and complications for the mother and the kittens are more likely. An intact (not spayed) female cat of reproductive age is called a queen.
Cats are induced ovulators, meaning that they only ovulate (release an egg from the ovary) if mated. If not mated (no ovulation), the estrus phase of the cycle will quickly return. Cats sometimes mate several times with different males during a single estrus so more than one male can be the sire within a litter.
What to Expect When Your Cat Is in Heat
Your cat will be extremely eager to mate due to the effects of her hormones. The behavioral signs of being in heat include:
- She yowls to attract attention and show she is eager to mate, although it can seem as if she is in pain.
- She will pace and may attempt to run out the door.
- She will rub against you or other objects. If you pet her, she may assume a mating position (hind end up with tail to the side).
- She may mark her territory by spraying.
These are all normal behaviors when in heat, but they can make an intact female cat difficult to live with during estrus. Unless your cat is a part of a breeding program, the best solution is to have her spayed.
Spaying Your Cat at the Right Time
It is recommended that you have a female pet cat spayed before her first heat, eliminating the risk of accidental pregnancy and reproductive diseases later on in life. Cats may be spayed while in heat (or pregnant), but there is an additional risk due to the engorged blood vessels and enlarged tissue of the reproductive tract, which is associated with a higher chance of bleeding during surgery and other complications. The cost of surgery while in heat or pregnant is often higher as well.