FIVE STAGES of the feline heat (estrus) cycle:

Proestrus

Not many signs are seen in the cat for this stage. The female is attractive to the male, but unwilling to mate. Length: 1-2 days.

Estrus

This is when the female cat is receptive to the male. External signs such as a swollen vulva or bloody discharge, are not as obvious in the cat as they are in the dog. The main signs seen 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: 3-14 days (average of one week). If the female is not mated, she may go back into heat within several days.

Interestrus

The period between estrus cycles if the female isn't bred. Length: 2-3 weeks.

Metestrus (or Diestrus)

The period after estrus or mating. Length: 30-40 days. If pregnant, pregnancy lasts on average 60-64 days in the cat.

Anestrus

The period of inactivity (sexual and hormonal) between estrus phases. Length: 2-3 months.

Some general "rules of thumb" for feline estrus

•The first estrus cycle usually occurs by age 4-12 months.

•Cats are considered to be seasonal breeders; most often showing signs of mating behavior in the spring and fall.

•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 return in 1 - 3 weeks.

•Multiple matings produce more ovulations; more than one male can be the sire of a litter.

•Cats can get pregnant during their first heat cycle, but this is not advisable as a 4-6 month old cat is not yet fully grown/mature, and complications for the mother and the kittens are more likely.