Spaying is the term commonly used for an "ovariohysterectomy", the surgical removal of the entire reproductive system including the uterus and ovaries of a female dog or cat. (The term neuter applies to both sexes and can be used to denote spaying in females and castration in males)

Spaying removes many of the problems associated with pregnancies. Spaying is still the only safe and reliable method of birth control in both dogs and cats. With humane societies and animals shelters overwhelmed with homeless and abandoned animals, spaying is an important way in which we can be responsible pet owners and not contribute to the problem of pet overpopulation.

Spaying a pet will ensure that the problems associated with heat cycles are avoided. For example, in dogs, the bloody discharge from the vulva, which can persist for two to three weeks during each heat period, can result in bloodstains around the house. This problem is further complicated by the fact that they must be kept indoors or be closely supervised when outdoors to prevent the unwelcome approaches of males. In cats, the excessive vocalization and behaviour associated with heats is also avoided if spaying is done. If not mated, female dogs may also experience "false pregnancy", a condition wherein they behave as if pregnant, complete with whining, restlessness and lactation even though no pregnancy has occurred.

Female dogs run an increased risk of life-threatening medical problems later on in life if they are not spayed. For example, there is an alarmingly high risk of contracting uterine infections in older females that are not neutered. These infections are often life threatening and in many cases the treatment of choice is surgical removal of the uterus.

Spaying a dog before its first heat greatly reduces the risk of mammary tumours. Studies have shown that the chances of breast cancer in female dogs increases significantly with each successive heat period until the age of two years. After two years of age, spaying does not really make any difference to the incidence of breast cancer.

Spaying will not make a pet fat or lazy. Obesity in pets is usually the result of overeating and a lack of exercise. Similarly, spaying does not change a pet's personality or temperament, whether for good or for bad.

Spaying is a very safe surgical procedure. Many owners delay the operation because of a concern for their pet's well being (i.e. aesthetic and/or surgical risks). Discuss these concerns with your veterinarian.