A complete discussion of breeding and reproduction in cats is beyond the scope of this book. And considering the surplus of pet cats in the US and other countries, casual rearing of litters by pet owners is not recommended. However, the following section includes a basic discussion of reproduction in cats.
Female cats (queens) are usually taken to the home of the male cat (tom) for breeding when they show signs of estrus. The breeding area should be quiet, familiar to the tom, and allow for observation with minimal interference from people. The courtship should not be interrupted unless there is a concern for the safety of either cat. Toms have been known to mate to the point of exhaustion, but queens usually go through a period of rolling and grooming after mating and may not let the tom remount for some time. Because cats are what is known as induced ovulators (see Reproductive Disorders of Cats: The Ovaries), multiple breedings over several days are recommended. Periods of separation between breedings may prevent exhaustion and fighting. Evaluation for pregnancy can be done by your veterinarian by physically examining (palpating) the abdomen or by ultrasonography. Pregnancy lasts 60 to 63 days and can be detected by day 25 to 30.
Unlike in other domestic species, manipulation of the estrous cycle is not easy in cats. Prevention of estrus is typically accomplished by spaying, although short-term suppression of estrus can also be achieved by medication. The side effects of medical suppression can include inflammation and infection of the uterus, diabetes, and mammary cancer. Ovulation can be induced in cats by physical stimulation (for example, mating with a vasectomized tom) or sometimes by injections of hormones.
Unplanned and unwanted mating of cats is a common concern. Pregnancy can be completely prevented or ended by spaying or neutering. Pregnancy can also be ended by a veterinarian giving the hormone prostaglandin F2alpha.
Pregnancy and Delivery
Predicting the timing of delivery can be difficult. Labor and delivery in cats is divided into 3 stages. Stage I lasts 12 to 24 hours. During this stage uterine contractions begin, but are not visible externally. The cervix also begins to dilate. During Stage II, abdominal contractions can be seen and the kittens are delivered. The kittens are usually delivered at intervals of 1 to 2 hours, but that can vary considerably. Stage II can last up to 24 hours. Stage III is defined as the delivery of the placenta. Cats typically alternate between stages II and III until delivery is complete.
Abnormal labor and delivery (dystocia) can be diagnosed if the uterine contractions are too infrequent or too weak to deliver the fetuses. This can lead to prolonged labor (more than 24 hours for stage I or II or more than 4 hours between delivery of kittens during stage II). Other signs of difficult birth include kittens that are born dead or near death or excessive maternal distress. Uterine and fetal monitors can be used to assess the condition of the uterus and fetuses. Dystocia can be treated either medically or surgically. Medical treatment includes injection of calcium or the hormone oxytocin to increase the strength and frequency of uterine contractions. Neither should be given without specific directions from your veterinarian. If these measures are not successful, cesarean section is performed to remove the fetuses.
Physical examination, and in some cases x-rays, are used to ensure that all kittens have been delivered. Injections of oxytocin are not routinely given unless the cat has not delivered all of the placentas. Disinfection of the umbilicus (belly button) with tincture of iodine helps prevent bacterial infection in the newborn kittens. Kittens should be weighed as soon as they are dry and then twice daily for the first week. Any weight loss after the first 24 hours indicates a potential problem and should be given immediate attention, such as extra feeding, assisted nursing, or examination by a veterinarian (see Routine Care and Breeding of Cats: Kitten Care).
Problems Associated with Delivery
Cats should be allowed to deliver their kittens in a familiar area where they will not be disturbed. Unfamiliar surroundings or strangers may hinder delivery, interfere with milk letdown, or adversely affect maternal instincts and cause the cat to neglect her newborn kittens. This is especially true for a cat delivering her first litter. A nervous cat may either ignore the newborn kittens or give them excess attention. This can lead to nearly continuous licking and biting at the umbilical stump, which can potentially cause serious injury to the kitten. If the cat's maternal instincts fail, she may ignore the kittens, leave them unattended, or not allow them to nurse.
Common inflammatory diseases in the period after delivery include inflammation of the uterus (metritis) and breasts (mastitis). Retention of a placenta usually leads to metritis (see Reproductive Disorders of Cats: Metritis). Signs include continued straining as if in labor, vaginal discharge, fever, and depression. Drugs that help stimulate uterine contractions such as oxytocin or prostaglandin F2alpha may help expel the placenta. Mastitis (see Reproductive Disorders of Cats: Mastitis) is uncommon in cats and is usually caused by a bacterial infection. It can be treated with appropriate antibiotics.
Lack of milk production (agalactia) is uncommon in cats, but can be associated with premature delivery of the litter. Cats that do not produce enough milk should be examined by a veterinarian to check for other underlying diseases. The normal presence of colostrum (a clear, watery fluid produced before milk and containing important antibodies) should not be confused with agalactia. Contented kittens that gain weight daily after the first 24 hours are a good indication that milk production is adequate. If necessary, milk production can be stimulated by injections of oxytocin. If milk production is inadequate, kittens may need supplemental feeding.
Last full review/revision July 2011 by Cheri A. Johnson, DVM, MS, DACVIM (Small Animal); James A. Flanders, DVM, DACVS; Autumn P. Davidson, DVM, MS, DACVIM; Fabio Del Piero, DVM, DACVP, PhD; Mushtaq A. Memon, BVSc, MS, PhD, DACT; Robert C. Rosenthal, DVM, PhD, DACVIM (Small Animal, Oncology), DACVR (Radiation Oncology); Brad E. Seguin, DVM, MS, PhD DACT