Feline Heat CycleUnlike dogs, female cats do not cycle at regular intervals throughout the year. Cats tend to come into heat in relation to the season. The mating season in cats is determined by a number of factors, including the length of daylight and the presence of other cats. When there are 10 hours of daylight and other conditions are optimal, the hormonal system is activated, and the queen begins the reproductive cycle. The natural mating season of cats in the Northern Hemisphere is from March to September. Long-haired cats are more sensitive to light and temperature than short-haired breeds. Cats under artificial lighting may come in heat anytime of the year, while house cats under intermittent light have unpredictable heat cycles.
Throughout the breeding season, queens go into and out of heat several times but not always at regular intervals. They may exhibit continuous heat cycles in early spring (averaging 14 to 21 days from the beginning of one cycle to the beginning of the next), followed in late spring by cycles that are further apart. Each queen establishes her own normal rhythm.
PUBERTYMost female cats reach puberty and have their first heat cycle between five and nine months of age, occasionally earlier. Yet we do not want her to becoming pregnant until the queen is physically and mentally ready. Persians as a breed are considered late matures and may not reach puberty until 1.5 years of age.
The estrous heat cycle or reproductive cycle of cats has four distinct stages: anestrous, proestrus, estrus and metestrus.
- Is where the queen does not come into heat and her ovaries are in a quiescent (inactive) stage. This would be the period of no sexual activity. In most areas of the United States, this would run from late September through mid-January. The low light and short length of daylight is a primary factor in suppressing the heat cycles during the winter months. Cats kept indoors may be stimulated to cycle from artificial light sources that are lengthening the queen's day. If light levels are similar to those experienced during the peak breeding seasons of early spring, they start cycling.
- Is used to describe the stage of estrous immediately following anestrus. In this stage of heat, the ovaries are becoming active in follicle formation. This lasts from one to four days. Unlike the bitch, the queen's vulva enlarges only slightly and appears somewhat moist, but no discharge comes from the hormonal changes. The queen shows increased appetite and restlessness, utters short low calls, and displays more than usual affection for her owner. This is best described as the period in which the cat is coming into heat, but is not yet ready to be bred. Hormones such as the follicle stimulating hormone (FSH) and estrogen help promote the egg development occurring during this phase.
- Is the period of the heat cycle when the cat is able to become pregnant. It is what breeders refer to as heat or the call, as queens can be quite vocal, yowling when in heat. Length is variable but usually lasts 10 to 14 days. During this period, the queen will insist the owner notice behavioral and other physical changes in the female. The queen "in heat" will vocalize and urinate frequently. She will appear overly passionate by rolling, rubbing and assuming the breeding posture with the head and forelegs low to the ground and the rump area held high. As the urge to mate becomes pronounced, her cries become alarming – sounding like those of an animal in pain. This "call" will attract toms from near and far. Unlike the female dog, the queen usually has little if any noticeable vaginal discharge in either the proestrus or estrus phase.
- Is the time immediately after estrus. The female will not pay attention or accept the male at this time and will return to her normal self.
The actual breeding or copulation takes place during the estrus phase. Copulation usually lasts 10 seconds or less, but although the time is short, most females will breed repeatedly over a 24 to 48 hour period, helping to ensure semen from the male is present and the queen's eggs are ovulated. Queens are "induced ovulators," meaning the act of breeding stimulates the female to release (ovulate) her eggs. Repeated breeding ensures ovulation with copulation happens as many as 36 times in 36 hours. In other mammals (dogs, cattle and humans), ovulation occurs even if breeding does not. A cat not bred will not ovulate, but will usually go out of heat within 10 to 14 days. Bitches will be in anestrous for 4.5 months, but the queen not induced to ovulate by breeding will come into heat every two to three weeks (or sooner) until breeding and ovulation occurs.
QUEEN PROBLEMSQueens have very little reproduction issues, but when they do, it is often related to lack of ovulation. This is an issue with submissive, extremely shy, intimidated queens. Little estrus behavior occurs and little copulation happens, as opposed to the queen that seeks the male. This lack of copulation numbers result in no ovulation and no pregnancy, in spite of a fertile male.
TREATMENTYoung males often do not repeatedly breed if the shy female does not exhibit breeding behavior. An experienced male will help and often breed in spite of the female's shyness. HCG can be given when copulation has happened and semen is present. Check for semen by collecting the vaginal discharge onto a slide. If semen is present, veterinarians have induced ovulation with 250 IU of HCG (Human Chorionic Gonadotropin) given IM.
It is possible to artificially induce ovulation in the cat with vaginal stimulation. A clean rectal thermometer can be lightly inserted in to the vagina to induce ovulation and therefore "knock" the queen out of heat. This is usually done to synchronize queens for embryo transfer or with AI when collecting eggs for embryo transfer.
If you need help, call us at 1-800-786-4751.
Don Bramlage, DVM, Director of Veterinary Services at Revival Animal Health
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