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Cats have a unique and
extremely variable reproductive cycle. They are seasonally
polyestrous. This means they cycle in and out of estrus, or “heat”,
based on the amount of seasonal light. In Stillwater most queens (female cats) will
cycle from January through October.
This is the mating period for female cats. Cats normally have their first estrous cycle
between 4-12 months of age depending on season, day length and breed.
Indoor cats with artificial lighting may cycle year-round. Each heat cycle lasts about one week with a short
two-week interval between cycles. Some cats will occasionally have no
obvious break between cycles and it is possible for an unmated
female to cycle every 3 to 4 weeks indefinitely.
Clinical Signs of Estrus
Behavioral changes are usually the only obvious sign your cat is in
heat. Signs of estrus include increased vocalization
and rolling on the ground, increased affection, hind quarters
elevated and holding the tail to the side, ‘treading” with hind
feet, and restlessness. Occasionally they will urinate small amounts
frequently and have a decreased appetite. Unlike the dog, cats
usually do not have obvious vaginal discharge or vulvar swelling during estrus. In fact, vaginal
discharge in a cat could be an indication that she has an infection
and needs medical attention.
Cats are induced ovulators. It is this unique feature that accounts for the seemingly endless estrus cycle of the feline. Unless the queen is bred, she will
continue to cycle every 2 weeks throughout the breeding season.
However if she is induced to ovulate, but is not impregnated she
will not cycle again for about 45 days. Obviously, pregnancy also ends the
estrus cycle for the duration of gestation and usually until the
litter is weaned at 6-8 weeks old. The cat’s unique reproductive
physiology accounts for the possibility for superfecundation, or
kittens sired by different males, and also for their impressive
reproductive capacity. With a short gestational length of only
63 days, a queen can produce 2.5 litters per year averaging 4
kittens per litter.
Prevention
The most reliable prevention of estrus
and unwanted pregnancies is ovariohysterectomy, or surgical removal
of the ovaries and uterus. In one study cats
spayed before 6 months of age had 91% reduction in risk of mammary
cancer compared to intact females, and those spayed before 1 year had
86% reduction in risk.
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