How long is a cat in heat?

posted: 05/15/12
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Get ready. When heat hits they'll howl.
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Female cats that aren't spayed seem to constantly sing loud love songs to potential mates. But feline heat cycles, or the period in which cats can become pregnant, are dormant in the short, dark days of late fall and winter, and return in full force with the arrival of longer days. If your cat has not been spayed, she can experience heat cycles from the earliest days of spring until Halloween. Here's what you need to know about the seemingly endless feline heat cycle:

What triggers feline heat?

It's no accident that during the warmer, brighter months of spring and summer we see a surge in pregnant cats. A cat comes into heat because of the decrease of a hormone called melatonin, which is secreted nightly by a gland in her brain. With the arrival of more daylight and shorter nights, melatonin production diminishes. This affects the hypothalamus, or the area of her brain that manages her heat cycle. The hypothalamus releases a reproductive hormone that travels to her pituitary gland, which in turn releases two more reproductive hormones that travel in her bloodstream to her ovaries where her eggs await fertilization.

How often do cats enter heat cycles?

Cats are polyestrus breeders, meaning they can go through multiple heat periods in a year (and can have as many as five litters in that year). They can come into heat every two to three weeks, for seven to 10 days, beginning in early spring and winding down in late autumn as the hours of daylight decrease (a cat needs at least 12 hours of daylight for a normal cycle). If the cat does not mate, her body will continue repeating the heat cycle until she does, or until she is spayed.

A cat that is not fixed and lives indoors and exposed to artificial light year-round may experience almost constant hormonal activity and many more periods of heat. A cat can experience her first heat cycle at the age of 4 months, when she is still on the fringe of kittenhood, and most cats have had their first heat at around 6 months old.

The long and short of heat

The entire heat cycle spans five stages. During proestrus, which lasts about two days, the cat is attractive to a male, but she is not willing to mate. A cat in proestrus may start becoming vocal, and raise her hind end. During estrus, the period when a cat's body is receptive to sexual activity, her behavior will be more affectionate, increasingly vocal and even frantic. Estrus can last from three to 16 days, with an average of seven days, before subsiding for three to 14 days. A cat only ovulates, or releases an egg from the ovary, if she mates; if no ovulation takes place, her body goes into interestrus, the time between estrus periods and then back to proestrus.

If ovulation occurs, diestrus follows. If the cat is pregnant, her body secretes progesterone. Her pregnancy will last around 60 days. If she is not pregnant, diestrus is termed a false pregnancy, and lasts about 40 days. During late fall and winter, when the fertility cycle diminishes, the cat's body is in anestrus, an inactive period.

The myth of feline menopause Those tabloid stories about 28-year-old cats giving birth are not entirely fabrication. If a cat is not fixed, she will be able to conceive all her life. There is no feline equivalent of menopause, because cats do not menstruate. Her fertility may decline but will not cease, and those familiar symptoms of heat, such as loud meowing, anxious behavior, even marking with her urine, will continue. An aging cat that is permitted to mate into her later years may produce smaller litters. Health issues, plus the strain of motherhood can result in a poorer quality of life for older cats. Even professional purebred cat breeders usually allow their cats to mate only until about age 5, when they generally have them spayed.

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