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.