The Heat

They were ready to mate
They were ready to mate

With the onset of Spring and the advent of warmer weather, comes the instinctive desire in female kitties to mate! What we will discuss here is feline female mating behavior. To begin with, here is a little information about what heat or the medical term, "estrus," is all about: Estrus ("heat") is the mating period of female animals. When estrus occurs, animals are said to be "in heat" or "in season". Female cats normally have their first estrous cycle between 5 and 10 months of age, with the average age around 6 months. The female cat has 2-4 estrous periods every year, each lasting 15-22 days. If she is bred, estrus seldom lasts more than 4 days. If successful mating does not occur, a heat cycle may last for 7-10 days and recur at 15-21 day intervals. It is possible for an unmated female to cycle every 3-4 weeks indefinitely. Cats also have an estrous period 1-6 weeks after giving birth, so a female may be nursing one litter while pregnant with another.

Please be very aware that a kitty in heat is very vocal, calling and calling for a male cat. Female cats also exhibit many strange behaviors when they are in heat. Here are signs and behaviors to look for:

  • Rolling on the floor and rubbing against objects with intensity. Flexing the claws and stretching may accompany the rolling. Also rubbing of the head or neck on objects as well.
  • As the heat cycle progresses, female kitties will start howling and this can go on for several minutes at a time.
  • Some females can even spray urine in the same manner that is usually associated with tomcats - lifting the tail and squirting urine on a vertical surface.
  • The female cat may adopt postures suggestive of a desire to mate - tail raised, rear end held high. A strong desire to escape the house may develop.

The cat is usually described as being seasonally polyestrous and a long day breeder. Queens cycle repeatedly during a breeding season unless interrupted by pregnancy, pseudopregnancy (false pregnancy), or illness. Estrous cycles will occur at intervals ranging from four to 30 days, but typically 14 to 21 days. Cats housed indoors, but largely under the influence of seasonal light, will cycle according to the season. Increasing daylight (i.e., January and February in the northern hemisphere) will increase the frequency of cycling. Queens housed together may have synchronized estrous cycles. Longhair cats seem to be more sensitive to the amount of daylight than shorthair cats. It has been said that only 10% of longhair cats show regular estrous cycles during breeding season, compared to 60% of shorthair cats. Over 50% of all shorthair cats will cycle year-round. Inadequate intensity or duration of light is one of the major reasons for cats kept indoors to have infrequent estrous cycles. It has been found that queens kept under a minimum of 10 hours (12 to 14 hours is better) of artificial light per day may cycle all year round. Cats kept in eight hours of daylight (and 16 hours of dark) will virtually stop cycling.

Stages of the Estrous Cycle

The queen has four stages in her estrous cycle. The stage just before estrus is called proestrus. In this stage, many queens begin to rub their head and neck against convenient objects and display affectionate behavior. Occasionally, queens in proestrus have a slight mucoid vulvar discharge and increased frequency of urination. This stage may last only one day or so, and the signs may be subtle, so it is often not detected. During proestrus, toms may be attracted to the queen but she will not be receptive. Estrus is the behavioral receptivity to mating. This stage may last from as little as one day to as long as 21 days, with the average duration being seven days. The queen will crouch with her front legs pressed to the ground, with her back in a position of lordosis (sway back), and her tail turned to one side to present the vulva. Queens in estrus often call or vocalize to attract the attention of males. They may be restless, have a poor appetite, and show increased affection to their owners.

Occasionally, queens with prolonged estrus are seen. In some cases, it is thought that this is due to the maturation of overlapping waves of follicles (and, therefore, prolonged high levels of the hormone estradiol). Other such cats, however, are having normal distinct patterns of follicular growth. Why these queens show prolonged estrus rather than distinct estrus periods is not understood. Persistent estrus can also be associated with cystic follicles.

Follicle stimulating hormone (FSH) produced by the pituitary gland in the brain initiates the development of ovarian follicles. An average of three to seven follicles develop and start producing the hormone estradiol-17b (a type of estrogen). It is the estradiol that causes behavioral estrus, which occurs as the follicular activity peaks, with blood estradiol levels reaching a high of 20 to 50 pg/ml (or higher). The estradiol levels stay high for three or four days and then abruptly fall.

Traditionally, queens are described as induced ovulators. Ovulation should not occur unless it is induced by mating or a similar stimulus. The length of estrus is not affected by whether ovulation does or does not occur. Some queens who have timid and shy personalities or who are at the low end of the social scale in the cattery may not show behavioral estrus even though their estrogen levels are increasing (silent heat). Some queens who fail to show behavioral estrus in one breeding season may show normal estrus behavior in the next one. The period between one estrus and the next in queens who have not ovulated is called the interestrus. During this time the blood estradiol level is low (under 15 pg/ml) and no sexual behaviors are seen. The time of interestrus can range from two to 19 days but on average is eight days.

The mating


Like lions, once a female is ready to mate, she will often do so, with more then one male. Outside, fights between males my occur, because a female in heat very likely makes Toms violate each others terretory. Although it has been reported that in city areas with a dens cat population, no such fights occur because Toms don't claim terretories. It is very common for a female to act agressivly during mating. Only if she does mate with a very familar male, like one from the same household, it has been seen that mating proceeds without any agrassion, even with licking each other before and after coupling. The fighting among the males however, has no impact one wich male is alowed to mate.

The queen choses the male by presenting herself to him in mating position. She is laying down, but holding her hindquaters up, possibly trippeling with her hindlegs and with the tail aside. The male will approche her from behind, graping her neck to make her hold still. Now the male will be pushing the female into position using his fore and espasially hindlegs. This also is to keep the females hindquaters up. Some females, espacially unexpiriend are likly to lower their hindquaters again, so it's difficult for the male to penetrate. In such situation, he will start trusting to find his belongings. If the Tom is unexpirienced, too, that can last a while. Once the position is correct, the male is most likely to ensure he has a good lovebite of the females neck before he penetrates. In many cases he will ejaculate immidiatly or rest for a few seconds without trusting. It is believed that the cat's anterior vagina will contract strongly, once stimulated. Maybe because of the barbs causing pain to the female, humping is not so commen among housecats. Although it seems to be neccessary for the Tom if he is to deliver a second, third or even fourth load. Very much unlike lions housecats do not have that kind of stamina. It would be unusual for a tom to mate more then two to four times a day. But the female surely will, if there are enough males present. In fact, the kittens of any resulting litter may well have diverent fathers.

Copulatory Ovulation

When a queen is bred, the tom's penis stimulates the anterior vagina and causes changes in brain chemistry via neurological and hormonal reflexes. A surge of luteinizing hormone (LH), produced by the pituitary gland in the brain, occurs within 15 minutes of each breeding. The maximum LH levels are reached after eight to 12 breedings. There is a minimum amount of stimulation needed to induce LH release, and this threshold level varies from cat to cat. Only about 50% of queens will ovulate after one breeding; however, most will ovulate after at least four breedings. By one day later, the LH level has returned to normal. The more times the queen is bred, the higher the level of LH, and a sufficient increase in LH is necessary to cause ovulation.

Ovulation typically occurs 30-50 hours after copulation. The eggs are viable for only about 25 hours after ovulation. Some queens do not release adequate levels of LH despite repeated breedings with fertile tomcats, but mating the queen several days later during the same estrus may result in ovulation. So the timing of breeding in the estrus cycle is important to achieve ovulation; either too early or too late may not achieve ovulation and fertilization (the best days to breed are days two to five of estrus). Following ovulation, progesterone levels rise within 24 hours, reaching 20 ng/ml at the end of estrus and a high of 40 to 50 ng/ml by 15 to 25 days post-ovulation. If the breeding is infertile, progesterone declines to under 2 ng/ml by day 40 to 50. Throughout a pregnancy, progesterone is maintained at levels over 40 ng/ml until approximately day 50, when the level drops back to under 1 ng/ml by term. Progesterone is not needed during the last 10 days or so of a pregnancy. As for other induced ovulators, the CL is the primary source of progesterone throughout pregnancy in the cat. The placenta produces little or no progesterone.

Fertilization occurs in the oviduct and then the fertilized eggs pass into a uterine horn by day four or five. Implantation in the uterine lining occurs 10 to 12 days after ovulation. Before they implant, the embryos space themselves out along the uterine horns so the developing fetuses will not be crowded. They may migrate from one horn to the other. In this process, some embryos are lost. The rate of implantation varies from 50% to over 90%, depending on how many eggs are ovulated. The average litter size is reported to be 4 to 4.5 kittens, but this is highly variable. The largest litters come from queens with the most ovulations.

Normal tomcat anatomy

The reproductive tract of the tomcat consists of the penis, two testicles, the scrotum, the prostate gland, two bulbourethral glands and the ductus deferens (also called the vas deferens). Sperm produced in the testicles is carried via the ductus deferens into the urethra. The prostate and bulbourethral glands play a small role by contributing secretions found in semen. Cat owners occasionally are surprised to find that tomcats also have nipples, but these are nonfunctional.

An intact male cat's penis showing prominent spines. A neutered male cat's penis showing no spines present.

The penis is covered by a protective sheath called the prepuce. During licking and grooming, or sometimes during stimulating play, the penis may protrude from the prepuce. The tip of the penis is called the glans, and it is covered with 120 to 150 penile spines that are directed backward, away from the end of the glans. These penile spines start to appear at about 12 weeks of age and are fully developed at puberty. They are absent in neutered male cats, disappearing by six weeks after castration.

Sperm production by the testicles starts by the age of five to nine months. While sperm may be present in the testicles, the actual age at which mating begins will vary with physical condition, body size, and season. On average, the onset of puberty is at eight to ten months of age and at a body weight of 2.5 kg; however, significant variation among breeds is seen.

In addition to sperm, the testicles also produce testosterone, which regulates secondary sex characteristics, such as development of jowls, and male sexual behavior, such as mating and spraying. Testosterone levels in the blood vary widely (from 0 to 5.9 ng/ml) in an episodic fashion. It can be normal to find an undetectable level, especially in a single blood sample. Castration causes an almost immediate drop in the blood levels of testosterone, but viable sperm may still be present for up to six weeks.

Problems with Mating Behavior

A tomcat may be unable to complete a breeding attempt if he is inexperienced, if he is nervous in his environment (it may take up to two months for a tom to settle into a new home), if he does not learn how to grasp the neck of the queen properly, or if he releases the queen too quickly. Toms with dental problems may not be able to grasp the queen's neck properly. Any painful condition, such as arthritis or other orthopedic problems, can impair breeding performance and reduce libido. As well, hair rings around the penis make penetration of the female difficult, so that the tom may display long bouts of unsuccessful pelvic thrusting. Malpositioning can occur if there is a significant size discrepancy between the two cats. With time and experience, most toms will learn to adjust their position to overcome size differences.

Successful stud cats must be physically, socially and sexually mature, so that it is usually best to wait until they are close to one year of age before breeding. A young tomcat may need to be bred to an experienced and patient queen to train his mating behavior. Young, inexperienced toms can be discouraged by an aggressive or dominant queen. Exercise restriction in a cage environment also may not allow the tom to feel comfortable enough to attempt to breed a female. In addition, stresses such as being shown can adversely affect a tom's libido.

Giving testosterone to toms with low libido will not help increase their libido. It appears that giving supplemental testosterone to tomcats actually lowers the level of testosterone within the testicles (despite increased blood levels), which will deprive sperm cells of adequate testosterone needed for development and cause sterility. Increased testosterone secretion in the tom can be stimulated in a meek or subordinate male, however, by an injection of GnRH (Cystorelin®, Factrel®, and others) about one hour before breeding.

Normal tomcats may also attempt to mount and breed queens not in heat, spays, other male cats (neutered or intact), kittens, or inanimate objects such as furry toys. Mating behavior usually disappears when a tom is neutered, but tomcats with much experience may continue to display mating behaviors for years after neutering.


Some catteries routinely use vasectomized tomcats (teaser toms) to help bring queens out of estrus when a pregnancy is not desired. Vasectomy can be accomplished by surgically removing a section of the ductus deferens through an incision. Live sperm may be present for up to six weeks after the procedure is done. Vasectomy does not alter libido or mating ability in adult toms.

Semen Collection and Examination

Collect semen
Collect semen!

Semen evaluation is not commonly performed in the cat outside of research and zoo settings. It is difficult to collect semen and the volumes obtained are small. There are two methods for collecting semen from tomcats: training to an artificial vagina and electroejaculation. Occasionally, a very docile tomcat can be trained to mount and ejaculate into an artificial vagina in the presence of a female in heat. It may take a few weeks of training and patience, but it has been reported that 20% of toms can be trained. Electroejaculation must be accomplished under general anesthesia and the equipment is not commonly available, which makes it impractical.

Most tomcats have less than 30% structurally abnormal sperm in an ejaculate. In lions, it is known that inbreeding, decreased testosterone levels and increased numbers of deformed sperm are interrelated. In the domestic cat, higher testosterone levels are associated with lower numbers of abnormal sperm.

A less invasive method of examining the sperm from a tomcat is to perform a vaginal flush on the queen immediately after a natural breeding to collect ejaculate. Interpretation of semen samples collected by this method, however, is difficult. When cats ejaculate, some sperm are discharged retrograde into the bladder. Another possible method to confirm a tomcat is producing sperm is to examine a urine sample from the tom just after he has bred a female. The simple presence or absence of sperm may be determined by these methods, although no information about the numbers or quality can be found this way.

Silent heats

Queens who are timid or low on the social scale of the cattery may have the hormonal events of estrous cycles in a normal fashion, but may not display estrus behavior. The same effect may occur in queens living in crowded conditions. One way to detect these cats is to use vaginal cytology. Also, blood samples may be analyzed every seven days for estradiol levels. A low estradiol level (under 15 pg/ml) indicates no hormonal estrus, therefore no silent heat exists; however, the estradiol level only stays high for a few days during estrus, so several blood samples may need to be taken over time to evaluate the hormonal events properly. If a queen is experiencing silent heats, it may help to remove her from the group of cats with which she has been living and house her separately or in a much smaller group to elevate her social status. Using a regime of 14 hours of daylight and 10 hours of darkness is also helpful. Conversely, the queen who is housed alone (such as a family pet) may not show estrus behavior until she is exposed to other queens in estrus. Exposure to a tomcat may also increase the chances she will display estrus behavior.

Breeding management

Queens have a lower chance of ovulation if they are bred too few times. Observing the behavior of the queen and the tom is also important. All the stages of mating should be observed – did the tom mount the queen successfully, did the queen give a coital cry and show the typical post-coital behaviors? If the coital cry and post-coital behavior did not occur, then a mating did not take place; however, some queens will display the typical post-coital behavior even if ejaculation did not occur. A vaginal swab or flush can be examined for the presence of sperm in order to verify intromission and ejaculation. It is important to know whether the queen appeared to be successfully bred or not, as different conditions apply to each situation. If it is difficult to observe breedings (some cats will not breed if they are observed), it can be very helpful to set up a videocamera for surveillance.


If the queen returns to estrus about 35-45 days after breeding, then a pseudopregnancy should be suspected – the queen ovulated but did not conceive. Pseudopregnancy can be confirmed by checking the queen's serum progesterone one to three weeks after breeding. Canine ELISA kits for serum progesterone (ICG Status-Pro®, Canine Ovulation Timing Test, Synbiotics) have been validated for use in the cat. Queens who ovulated but did not conceive should be suspected of having cystic endometrial hyperplasia. The fertility of the tomcat should be examined, however, if several queens he breeds are experiencing pseudopregnancies. If the queen does not return to estrus for 60 days after the breeding, ovulation and fertilization likely occurred; however, the embryos or fetuses may have been resorbed, and all the causes of abortion and resorption must be considered.

Care of the Pregnant Queen

Most queens display no significant changes in behavior for about the first three weeks of pregnancy. There is usually no increase in appetite, no change in activity levels. Very rarely, a form of morning sickness may occur which is short-lived. There is no need to restrict the queen's activity due to the pregnancy; however, it is best to avoid unnecessary exposure to other cats to reduce the risk of the queen contracting an infectious disease. Pregnant cats should not be exhibited, and trips away from home should be avoided unless absolutely necessary. If a queen has been shipped by air to be bred, the optimum time to travel home is during the first two weeks after breeding, and the pregnant queen should never be sedated for travel. Once the first few weeks have passed, the stress of travel could be detrimental to the pregnancy. We do not fully understand the effects of high altitude and pressure changes on animals traveling by air.

By about the end of the third week pinking of the nipples may be noticeable, especially with a first pregnancy. Gradually the hair around the nipples tends to recede as the nipples enlarge, becoming more prominent and making them easier for the newborn kittens to find. Longhair cats may be best kept clean by clipping the hair around the perineum and on the abdomen around the nipples.

By about the fifth week of pregnancy the fetuses have grown significantly and the queen's abdomen has expanded. She may require more food at this point and feeding small, frequent high quality meals is important. The queen's appetite during pregnancy may increase from 25% to 50%. Many breeders will feed a kitten or growth type diet to pregnant queens during the last two to three weeks of pregnancy. This diet is especially helpful during nursing, when the queen needs to produce large quantities of milk and therefore needs more calories and protein in her diet. Many nursing queens eat twice as much food as when not nursing. It is not necessary to feed this type of diet from the start of the pregnancy unless the queen is underweight or not in optimal condition. Unnecessary weight gain from excess nutrition during pregnancy should be avoided as it may contribute to difficulties during labor and delivery. Some queens will develop digestive upsets, such as diarrhea and/or vomiting, when fed growth diets. In these queens a high quality adult maintenance diet is best. Dietary supplementation should be avoided.

Stages of Labor

Stage One: The first stage of labor may pass largely unnoticed. During this stage, the cervix dilates and the uterus starts contracting. It can last for a few hours or for as long as 24 hours. Queens may be restless, overgrooming, pacing, panting, or even vomiting during this stage. They may not eat for up to 24 hours before active labor, although some queens eat normally right up to stage two. No visible contractions are seen, although there may be a clear mucous discharge from the vagina. As the end of stage one labor approaches, most queens will settle in the birthing box, purring loudly and scratching around to prepare their "nest." It is important to ensure that the location where the queen will give birth is warm enough for the neonatal kittens.

Stages Two and Three: During these stages of labor the kittens are delivered (stage two) and the placentas are delivered (stage three). The delivery of the litter is actually a series of stage two and stage three labors. Strong uterine contractions help deliver each kitten from its uterine horn into the uterine body and through the cervix and vagina. Once strong labor starts the entire litter may be born in under two hours, or it may take as long as 24 hours. Most commonly, kittens are delivered every 30 to 60 minutes, although they may be delivered more rapidly. Both head first (2/3 of births) and hindquarters first (1/3 of births) presentations are normal in the cat. A true breech birth is when the tail and rump are presented before the hind legs, and this is a more difficult delivery. The time from the start of active labor to the birth of the first kitten is usually less than 60 minutes. A queen who is in active, hard labor for two hours without delivering a kitten must be assumed to need veterinary attention.

As each kitten is born, many queens will pause to break open the amniotic sac if it is still intact and clean the membranes away from the newborn, stimulating breathing. The amniotic sac is often ruptured by the queen during licking at her perineum as the kitten is being delivered. Not all queens show interest in eating the placentas and there is no evidence to show that it is necessary. Queens will sever the umbilical cord with their teeth. In some cases the kittens arrive too rapidly for the queen to clean each one and sever the umbilical cord.

The breeder should be prepared to dry off each kitten to prevent it from chilling and to stimulate breathing if 10 minutes has gone by without the queen attending to the newborn. It is preferable to tear the umbilical cord with clean fingers, leaving it about two to three inches long, rather than to cut it, as there will be less bleeding and less chance of infection. It is acceptable, however, to tie a piece of thread or dental floss tightly around the umbilical cord about two to three inches from the kitten's abdomen after "milking" the blood in the cord away from the placenta and toward the kitten. A second tie is placed just beyond the first and the cord is cut with a pair of sharp, clean scissors (preferably swabbed with alcohol) in between the two ties.

The stump of each umbilical cord should always be dipped in 2% tincture of iodine to prevent infection. It is important to avoid having kittens crawling around the birthing box while their umbilical cords and placentas are still attached. The cords of the kittens can become entwined and cause tension on the umbilical area, which may lead to a hernia, or the cords can become entwined around a kitten's leg causing trauma. Sometimes, kittens are born with the placentas already detached, so it is important to count the number of placentas when labor is finished. In most cases, there is one placenta for every kitten, although twins and triplets sharing the same placenta do occur.

Cherish Resting

Occasionally queens may pause during labor and rest without having uterine contractions. This may be for an hour or two or, rarely, it can be for up to 24 hours. She may nurse the kittens already born, giving the appearance that delivery is finished. Queens are more likely to interrupt labor and delivery if something disturbing occurs in their environment. In general, the queen should be monitored but interfered with as little as possible. Labor and delivery can be made longer by inappropriate intervention by the breeder or curious onlookers. That having been said, there are queens who will be very restless unless their owner is present. Maiden queens need to be watched most closely as they may neglect to clean kittens adequately, especially if the time interval between kittens is small. In this situation, it is best to care for each newborn and remove it from the birthing box to a separate warm box until the whole litter is born.