Spaying and neutering

For other uses of Spay, see Spay (disambiguation).

Spaying and neutering are the respective surgical processes of female and male animal sterilization, to keep them from producing offspring. Neutering is sometimes used to refer to the surgery in either males or females. The process in males is also referred to as castration, or gelding.

Unlike in humans, sterilization in animals usually involves the outright removal of sexual organs. While many agree on the advantages of sterilization as a method of birth control, the necessity and humanity of spaying and neutering, as opposed to alternative methods of birth control, and the political agendas within the debate, are a subject of some controversy.

Household pets

Most humane societies, animal shelters, and rescue groups (not to mention numerous commercial entities) urge pet owners to have their pets "spayed or neutered" to prevent the births of unwanted litters, contributing to the overpopulation of animals.

Additionally, spaying and neutering have health benefits. Uterine, ovarian, and testicular cancer are prevented (although these cancers are not common in household animals), and hormone-driven diseases such as benign prostatic hypertrophy become a non-issue as well. Female cats and dogs are seven times more likely to develop mammary tumors if they are not spayed before their first heat cycle. Unspayed dogs have a 25% chance of developing mammary tumors, about 50% of which are malignant. A dangerous common uterine infection known as pyometra is also prevented.

Immediate complications of spaying and neutering include anesthetic and surgical complications. In the long run, dogs of both genders have an increased risk of obesity due to the fact that pet owners continue to feed as if the animal was still intact; this can be easily prevented by modifying the diet. Spayed female dogs sometimes develop urinary incontinence, and neutered males display a somewhat increased incidence of prostate cancer over intact males. Spayed and neutered dogs have also been known to develop hormone-responsive alopecia (hair loss). Neutered male cats are more prone to urethral obstruction due to narrowing of the urethra.

The procedures may also help to address behavioral issues that might otherwise result in animals being given up to shelters, abandoned, or euthanised. Obviously, the animals lose their libido, and females no longer experience heat cycles, which may be a major nuisance factor, especially in female cats. This is due to the hormonal changes involved with both genders. Minor personality changes may occur in the animal. Neutering is often recommended in cases of undesirable behavior in dogs, although studies suggest that while roaming, urine marking, and mounting are reduced in neutered males, it has little effect on aggression and other important behavioral issues. Intact male cats are more prone to urine spraying, although many common behavioral causes of urine marking remain in neutered cats.

Methods

Traditional spay/neuter

Spaying of a female cat.

Traditionally, spay and neuter has been achieved by surgical techniques involving gross removal of the entire organs involved in the progenetary process. In females, this is known as spaying, and involves complete surgical removal of the ovaries and uterus (womb). In males it is known as neutering (or castration), and involves removal of the entire male testes (testicles).

Female (spay)

In female animals, spaying involves abdominal surgery to remove the ovaries and uterus (ovariohysterectomy). It is commonly practiced on household pets such as cats and dogs as a method of birth control, but is rarely performed on livestock.

The surgery is usually performed through a ventral (belly) midline incision below the umbilicus (belly button). The incision size varies depending upon the surgeon and the size of the animal. The uterine horns are identified and the ovaries are found by following the horns to their ends.

Canine Uterus

There is a ligament that attaches the ovaries to the kidneys which needs to be broken so the ovaries can be identified. The ovarian arteries are then ligated twice (tied-off) with absorbable suture material and then the arteries transected (cut). The uterine body (which is very short in litter bearing species) and related arteries are also tied off just in front of the cervix (leaving the cervix as a natural barrier). The entire uterus and ovaries are then removed. The abdomen is checked for bleeding and then closed with a 3 layer closure. The linea alba (muscle layer) and then the subcutaneous layer (fat under skin) are closed with absorbable suture material. The skin is then stapled, sutured, or glued closed.

See also oophorectomy and hysterectomy.

Males (neuter/castration)

In male animals, neutering involves the removal of the testes, and is commonly practiced on both household pets (for birth control) and on livestock (for birth control, as well as to improve commercial value).

For more information, see castration.

Modern nonsurgical alternatives

Injectable

* Male dogs - Neutersol (Zinc gluconate neutralized by arginine). Cytotoxic; produces infertility by chemical disruption of the testicle.
* Female mammals - "SpayVac" (purified porcine zona pellucida antigens encapsulated in liposomes - cholesterol and lecithin - with an adjuvant.) Produces infertility by inducing an immune response to the egg.

Other

* Noninvasive vasectomy using ultrasound.

Terminology for neutered animals

Male animals

Neutered males of given animal species sometimes have specific names:
*Barrow (pig)
*Bullock (cattle)
*Capon (chicken)
*Dinmont (sheep, goat)
*Gelding (horse)
*Gib (cat, ferret)
*Havier (deer)
*Hog (pig)
*Lapin (rabbit)
*Ox (cattle)
*Stag (primarily cattle)
*Steer (cattle)
*Wether (sheep)

Female animals

A specialized vocabulary in animal husbandry and -fancy has arisen for spayed females of given animal species:
*Sprite (ferret)
*Poulard (chicken)

Miscellaneous

* TV celebrity Bob Barker helped to popularize the spay-or-neuter drive by closing every episode of The Price Is Right with a request for people to help control the pet population by spaying or neutering their pets.
* Orthodox Judaism forbids the castration of either humans or animals.