Neutering

Neutering, from the Latin neuter (of neither sex^[1]), is the removal of an animal's reproductive organ, either all of it or a considerably large part. It is the most drastic surgical procedure with sterilizing purposes. The process is also referred to as castration for males and as spaying for females. Colloquially, it is often referred to as fixing. In male horses, the process is referred to as gelding.

Unlike in humans, neutering is the most common sterilizing method in animals. In the United States, 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. In Europe, the procedure is less commonly performed, especially in dogs.

Contents 1 Health and behavioral effects 1.1 Advantages 1.2 Disadvantages 1.2.1 General 1.2.2 Specific to Males 1.2.3 Specific to Females 1.3 Ambiguous 2 Methods 2.1 Females (spaying) 2.2 Males (castration) 3 Nonsurgical alternatives 3.1 Injectable 3.2 Other 4 Surgical alternatives 5 Terminology for neutered animals 5.1 Male animals 5.2 Female animals 6 Religious views on neutering 6.1 Christianity 6.2 Judaism 6.3 Islam 7 Miscellaneous 8 References 9 External links

Health and behavioral effects

Advantages

Altering has the following health benefits:

• Female cats and dogs are seven times more likely to develop mammary tumors if they are not spayed before their first heat cycle.^[2] The risk is generally estimated at 25% over a lifetime in unspayed females, meaning that the risk is reduced to ca. 3.6% over a lifetime in females spayed before ther first heat.
• Pyometra is prevented, either due to the removal of the organ (when ovariohysterectomy is performed) or due to the cervix remaining permanently closed because of the lack of oestrogens caused by spaying.
• Uterine cancer, Ovarian cancer and Testicular cancer are prevented due to the removal of the susceptible organs. These cancers are uncommon in dogs and cats, with only a 1% risk of obtaining testicular or ovarian cancer. In female rabbits, however, the rate of uterine cancer may be as high as 80%. ^[3]

Disadvantages

General

• As with any surgical procedure, immediate complications of neutering include the usual anesthetic and surgical complications, such as bleeding and infection. These risks are relatively low in routine spaying and neutering; however, they may be increased for some animals due to other pre-existing health factors.
• Neutered dogs of both genders are at a twofold excess risk to develop osteosarcoma as compared to intact dogs^[4],^[5][6] as well as an increased risk of hemangiosarcoma^[7][8] and urinary tract cancer.^[9]

• Neutered dogs of both genders have an increased risk of adverse reactions to vaccinations.^[10]

• Neutered dogs have also been known to develop hormone-responsive alopecia (hair loss).^[11]

Specific to Males

• Neutered male dogs display a fourfold increased incidence of prostate cancer over intact males.^[12][13]

• In addition, neutered male dogs are at higher risk than intact males of developing moderate to severe geriatric cognitive impairment (geriatric cognitive impairment includes disorientation in the house or outdoors, changes in social interactions with human family members, loss of house training, and changes in the sleep-wake cycle).^[14]

• As compared to intact males, male neutered cats are at an increased risk for certain problems associated with feline lower urinary tract disease, including the presence of stones or a plug in the urethra and urethral blockage.^[15]

Specific to Females

• Spayed female dogs can develop urinary incontinence.^[16][17][18]
• Spayed female dogs are at an increased risk of hypothyroidism^[19]
• Despite the risk of pyometra being greatly reduced in spayed females, Stump pyometra may still occur in this group.

Ambiguous

Most animals lose their libido due to the hormonal changes involved with both genders, and females no longer experience heat cycles, which are sometimes considered a major nuisance factor, especially in female cats. Minor personality changes may occur in the animal. Studies indicate that mounting was reduced in about 60% of neutered males, but one study found little effect of neutering on aggression and other issues.^[20] Intact male cats are more prone to urine spraying.

Methods

Females (spaying)

In female animals, spaying involves abdominal surgery to remove the ovaries and uterus (ovario-hysterectomy). Alternatively, it is also possible to remove only the ovaries (ovariectomy), which is mainly done in cats and young female dogs. Spaying is performed commonly on household pets such as cats and dogs, as a method of birth control. It is performed less commonly on livestock, as a method of birth control or for other reasons. In mares, these other reasons include behavior modification.^[21]

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.

There is a ligament that attaches the ovaries to the kidneys which may need to be broken so the ovaries can be identified. The ovarian arteries are then ligated (tied off) with resorbable 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 resorbable suture material. The skin is then stapled, sutured, or glued closed.

See also oophorectomy and hysterectomy.

Males (castration)

In male animals, castration 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 and gelding (specific to horses).

Nonsurgical alternatives

Injectable

• Male dogs - Neutersol (Zinc gluconate neutralized by arginine). Cytotoxic; produces infertility by chemical disruption of the testicle. It is now produced as Esterilsol in Mexico.^[22]
• Male rats - Adjudin (analogue of indazole-carboxylic acid), induces reversible germ cell loss from the seminiferous epithelium by disrupting cell adhesion function between nurse cells and immature sperm cells, preventing maturation.
• Male sheep and pigs - Wireless Microvalve.^[23] Using a piezoelectric polymer that will deform when exposed to a specific electric field broadcast from a key fob (like a car alarm) the valve will open or close, preventing the passage of sperm, but not seminal fluid. Located in a section of the vas deferens that occurs just after the epididymis, the implantation can be carried out by use of a hypodermic needle.
• Female mammals - Vaccine of antigens (derived from purified Porcine zona pellucida) encapsulated in liposomes (cholesterol and lecithin) with an adjuvant, latest US patent RE37,224 (as of 2006-06-06), CA patent 2137263 (issued 1999-06-15). Product commercially known as SpayVac,^[24] a single injection causes a treated female mammal to produce antibodies that bind to ZP3 on the surface of her ovum, blocking sperm from fertilizing it for periods from 22 months up to 7 years (depending on the animal^[25][26]). This will not prevent the animal from going into heat (ovulating) and other than birth control, none of the above mentioned advantages or disadvantages apply.

Other

• Noninvasive vasectomy using ultrasound.^[27]

Surgical alternatives

Vasectomy: The cutting and tying of the vasa deferentia (plural of vas deferens). Failure rates are insignificantly small.

Tubal Ligation: Snipping and tying of fallopian tubes as a sterilization measure can be performed on female cats and dogs. Risk of unwanted pregnancies is insignificantly small. Only a few veterinarians will perform the procedure.

Like other forms of neutering, vasectomy and tubal ligation eliminate the ability to produce offspring. They differ from neutering in that they leave the animal's levels and patterns of sex hormone unchanged. Both sexes will retain their normal reproductive behavior, and other than birth control, none of the advantages and disadvantages listed above apply. This method is favored by some of the people who want to infringe on the natural state of companion animals as little as necessary to achieve the reduction of unwanted births of cats and dogs.

Penile translocation is sometimes performed in cattle to produce a "teaser bull", which retains its full libido, but is incapable of intromission. This is done to identify estrous cows without the risk of transmitting venereal diseases. [1]

Terminology for neutered animals

Male animals

Neutered males of given animal species sometimes have specific names:

• Cat, ferret - Gib
• Cattle - Bullock, Ox, Steer, Stag
• Chicken - Capon
• Deer - Havier
• Goat - Wether, Dinmont
• Horse - Gelding
• Pig - Barrow
• Rabbit - Lapin
• Sheep - Wether, Dinmont

Female animals

A specialized vocabulary in animal husbandry and fancy has arisen for spayed females of given animal species:

• Chicken - Poulard
• Ferret - Sprite

Religious views on neutering

Christianity

Castration was a popular method for obtaining high ranks in the Byzantine Empire, and many Nobles (Eunuchs) and Patriarchs in the Eastern Orthodox Church were castrated. Nonetheless, it is forbidden in the Church today.

Judaism

Traditional interpretations of Orthodox Judaism forbids the castration of both humans and animals by Jews,^[28] except in lifesaving situations.^[29].

Islam

While there are differing views in Islam with regard to neutering animals,^[30] some Islamic association have stated that when done to maintain the health and welfare of both the animals and the community, neutering is allowed on the basis of 'maslahat' (general good)^[31] or "choos[ing] the lesser of two evils".^[32]

Miscellaneous

• In the movie Shrek 2, Donkey proposed that Puss in Boots be given the "Bob Barker Treatment", an indirect reference to neutering.

References

External links

• DVM Article on health effects of spay/neuter: Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs
• CanineSports.com article: Early Spay-Neuter Considerations for the Canine Athlete