Having your pet spayed (ovariohysterectomy) or neutered (castrated) is an inexpensive and realistic method of pet population control. The number of unwanted adult and young animals that are euthanized each year in the United States is astounding. Aside from the pet overpopulation problem, neutering a male dog and spaying a female helps prevent, and even eliminates, medical problems associated with hormonal imbalances.

Male and female dogs reach sexual maturity around nine months of age. Often, male dogs reach maturity slightly later than females. Sometimes confusion exists between sexual maturity and normal puppy behavior. Normal puppy behavior is often exhibited when he or she straddles the leg(s) of an individual. This behavior has nothing to do with sexual maturity and is performed by both male and female puppies.

It is usually noticeable when a female dog (bitch) reaches sexual maturity. A bloody discharge is seen around her external genital area. This bloody discharge is significant and can last up to 10-14 days. Along with the discharge, the external genitals become swollen. This is the first phase of her heat cycle and is called "estrus." During the last few days of the estrus phase, the bitch is receptive to the male and can get pregnant. Similar to cats, the gestation period lasts about two months. At the end of the two-month gestation period, puppies (puppies, not a puppy) are born. A typical litter size averages between five to 10 puppies.

Aside from having puppies, non-spayed females are more susceptible to mammary gland tumors and uterine infections. Pyometras (infections of the uterus) are extremely common in non-spayed bitches and almost always require emergency surgery. Mammary tumors get large and multiply quickly if left untreated. Having your dog spayed can eliminate both of these conditions.

Having your male dog neutered makes him a better pet. Instead of roaming, he will spend more time at home. Non-neutered male dogs often exhibit aggressive behavior, especially if a non-spayed female is in the vicinity. Dog fights between two non-neutered dogs are not uncommon. Usually one of the dogs ends up severely injured.

An aggressive dog will not hesitate to bite a human. Often, non-spayed and non-neutered dogs are significantly more aggressive than spayed and neutered animals. Many people receive serious injuries resulting from dog bites.

Dog neuters and spays are generally performed when animals are six to nine months of age.