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Estrus (Heat) in the Bitch and Queen

The fertile period of a female animal's reproductive cycle is called estrus, commonly referred to as "heat." The female will not mate with a male except during this period. The average female cat (queen) or dog (bitch) reaches sexual maturity at about 6 months of age. Some female cats and small-breed dogs begin to cycle sooner. Female cats reared indoors in the absence of a tomcat (uncastrated male cat) may not come into heat until later. Large-breed female dogs may not have their first estrous period until 9 or 10 months of age. The first cycle may be so subtle or mild that it goes unnoticed.

Mating Behavior in Queens
Beginning at puberty, estrus in queens normally occurs about every 3 weeks between January and November. Each estrual period lasts about 1 week, with about 2 weeks between the end of one cycle and the beginning of the next. During estrus, the queen becomes increasingly restless, and may eat and sleep less. Housecats in heat may try to escape. The queen may vocalize excessively, sometimes crying in a loud and plaintive tone. She may roll on her back, becoming more docile and solicitous of petting or attention. She may groom herself more, frequently licking her vulva. During peak estrual behavior, the queen presents her hindquarters, elevating her hips by leaning on her forepaws with tail quivering. This behavior becomes more and more insistent. The estrual queen may display this behavior toward her owners, who may at first find it amusing. After several sleepless nights, however, they may be less entertained. Estrus is a stressful and exhausting experience for the queen, who may eat and sleep less despite heightened levels of activity. Weight loss is not unusal during heat. Because the queen cycles so frequently, she may not have adequate time to regain lost weight before the next cycle begins. Changes in temperament, ranging from lethargy to irritability, may be observed in queens between heat cycles. Queens advertise their reproductive status by chemical signs in urine and vaginal secretions. The scent attracts tomcats across many barriers, leading them to your home even if the queen is indoors. Immediately after mating, the queen may briefly show aggression toward the tomcat. This behavior is normal. Unless purebred queens are intended for breeding, females should be spayed before heat cycles begin. Rather than allowing your cat to roam outdoors and possibly be injured or become pregnant, keep your cat indoors at least until it is spayed, and preferably also after it is spayed.


Mating Behavior in Bitches
Bitches normally go into "heat" every 6 months. Each cycle normally lasts 1-2 weeks. A bitch in heat may show little change in temperament or activity as compared with the exaggerated displays of many female cats. Some dogs become somewhat lethargic, while others become anxious and possibly aggressive. The bitch may become restless, making frequent escape attempts. At no time should a bitch in heat be left unsupervised in the backyard or off a leash during walks. Close supervision prevents undesired mating or injury. During walks, the estrual female urinates more frequently than usual, leaving a trail of scent to your home. Male dogs can detect powerful chemical signals in vaginal secretions and urine from a distance of several miles. The estrual bitch may also attract neutered dogs that are aroused by the changes they sense. If your dog has been undesirably bred, contact your veterinarian within the first few days after mating to discuss your options. Physical changes associated with estrus tend to be more obvious in bitches than in queens. The nipples may become slightly enlarged in anticipation of milk production associated with pregnancy. The vulva may appear inflamed and swollen, with a normal bloody discharge. These physical changes normally regress if the bitch does not become pregnant. During intercourse, the male dog's penis becomes engorged with blood, and the male may be unable to detach himself from the female for as long as a half hour. During this period, it is normal for the male to dismount and stand tail to tail with the female, joined by his penis. Do not be alarmed by this sight, and do not try to separate them. When the male dog's erection subsides, the dogs become separated.


Spaying Prevents Estrus
There are many more reasons to have your pet spayed than not to have it spayed. An animal does not have to experience "heat" or have a litter to lead a healthy and happy life. In fact, their lives may be healthier and happier because neutering may prevent many physical problems and emotional stress. Spaying female animals prevents unwanted pregnancies and keeps your pet from contributing to overpopulation of pets. Millions of dogs and cats are needlessly destroyed every year. Spaying your pet also avoids the risk of infection and trauma from mating and the complications of a difficult pregnancy and delivery. Uterine infections can occur in dogs and cats of all ages but may be even more dangerous in older females. Spayed pets, particularly those neutered before the first heat, have a decreased risk of developing malignant mammary tumors later in life. A female dog or cat is unlikely to develop any dramatic improvement in temperament by delaying or not having spay surgery. Similarly, there is no behavioral advantage to breeding or to the experience of delivering and caring for a litter. In fact, the opposite may be true. Do not use your pets to educate children about the "facts of life" when there are so many other appropriate teaching references available. Considering the emotional and physical stress endured by cycling females, spaying a pet is an act of kindness