Estrus (Heat) - or why has my cat
started acting nuts?!

The fertile period of a female animal's reproductive cycle (the mating period) is called estrus, commonly referred to as "heat" or being "in season". 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.

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, estrus may last for 7-10 days and recur at 15- to 21-day intervals. Estrus in cats most often occurs during the seasons of spring and fall. During these seasons, an unmated female cat may come in and out of heat continuously until she is bred.

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.

Cats also have an estrous period 1-6 weeks after giving birth, so a female may be nursing one litter while pregnant with another.

Mating Behavior in Queens (female cats)
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.

Since there is usually no obvious vaginal discharge or swelling of the genitals during estrus in cats, as is seen in dogs, behavioral changes are the only obvious signs that your cat is in estrus.

A cat in estrus carries her tail to one side, keeps her hindquarters elevated, exhibits "treading" movements of the hind legs, and seems unusually affectionate. She spends a good deal of time rolling on the floor and seems much more restless than usual. The cat's voice seems more piercing than usual and she may "call" for 1-2 days before she accepts the male.

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 unusual 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.

Spaying Prevents Estrus
Spaying your female cat or dog is a surgical procedure usually performed at 6 to 8 months of age. 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.
• Eliminates unwanted heats and the annoying behavior associated with the estrus cycle.
• Spayed pets, particularly those spayed before the first heat, have a decreased risk of developing malignant mammary tumors later in life. Spaying helps protect your pet against the risk of ovarian and uterine cancer and uterine infection (pyometra).
• 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.
• There is no scientific evidence that your pet will in any way benefit from having a heat and/or litter before spaying. Although hormonal changes after the surgery may temporarily increase her appetite, weight gain can be controlled by adjusting the type or amount of food given.

A few words about neutering your male pet:

Neutered pets make better pets. They stay at home more instead of roaming and getting into fights. Neutered males don't get testicular cancer either. The surgery consists of removing both testicles. We urge you to have it done.

Considering the emotional and physical stress endured by cycling females, spaying a pet is an act of kindness. Unless you are sincerely convinced that you want your dog or cat to have a litter, we recommend this important procedure. Feel free to call us if you have any questions.