Reproduction Index Glossary

Surgical Sterilization of Dogs and Cats

Surgical sterilization has been the cornerstone of efforts to curb pet overpopulation. While undoubtedly effective in preventing reproduction in individual animals, surgical techniques are far from ideal tools for the simple reason that they are expensive. Many owners cannot afford or choose not to spend the money to "neuter" their pets. Additionally, the procedures requires general anesthesia and invasive surgery, which, while generally very safe, imposes some risk to the animal. Nonetheless, surgical sterilization remains a valuable means of blunting increases in populations of pets.


The most widely used techniques for surgical sterilization of pets involve removal of the gonads (gonadectomy). Terminology and procedures differ between the two sexes:

  • In males, each testis with attached epididymis is removed in a procedure commonly referred to as "neutering" or castration. In dogs, both gonads are usually removed through a single incision made just anterior to the scrotum and the incision is sutured closed. Typically in cats, an incision is made into each side of the scrotum and left open to heal.
  • In females, the uterus is removed in concert with both ovaries in a procedure called "spaying" or ovariohysterectomy. This procedure is usually performed through a incision in the midventral abdomen, although some veterinarians prefer a flank incision. The reason for removal of the uterus is to eliminate the possibility of uterine disease following the sterilization.

Each of these procedures is performed under general anesthesia, which presents a small but finite risk to the animal. As with any surgical procedure, there are occasional complications, including bleeding, infection, or dehiscence (breakdown of the suture line, sometimes from the animal chewing), and postoperative observation is clearly warranted.

In addition to eliminating animals from the breeding pool, gonadectomy has a number of beneficial effects on the animal's health, and from the viewpoint of most owners, on the animal's behavior.

Castration and spaying are most commonly performed on dogs and cats that are 6 or more months old. This practice is at odds with efforts to control pet populations because many animals enter or are approaching puberty by that time, and even a short delay can result in the animal producing offspring. Clearly, it would be advantageous to sterilize most pets well before puberty, and a significant body of research now supports the safety and efficacy of early spay-neuter programs for dogs and cats.

Other Techniques for Surgical Sterilization

Surgical techniques not involving the removal of gonads have been applied, though not commonly, to dogs and cats. Vasectomy (cutting the vas deferens) in males and tubal ligation (tying off and cutting the oviducts) in females are not significantly easier to perform that gonadectomy. Although these procedures eliminate the animal from the breeding population, they do not provide the other benefits to animal and owner that are obtained with gonadecomy and are not widely practiced.

Index of: Animal Population Control
Introduction and Index Nonsurgical Sterilization of Dogs and Cats

Last updated on April 25, 2006
Author: R. Bowen
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