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Why is neutering (sterilization) of pets necessary?

Updated: Feb 17, 2022

What is neutering (sterilization)?


Neutering is from the Latin word neuter that refers to the removal of an animal's reproductive system, either all of it or a considerably large part of it. "Neutering" applies to both sexes, with the male-specific term being castration, while spay or spaying is usually preserved for female animals. Informally, both terms are often referred to as fixing or sterilization. In other times, the term de-sexing is used. An animal that has not been neutered is sometimes referred to as entire or intact.

Why is neutering important?


Neutering is the most common method for animal sterilization. Humane animal societies, shelters, and rescue groups encourage pet owners to have their pets neutered to prevent the births of unwanted litters, which contribute to the overpopulation of unwanted animals. Many countries require that all adopted cats and dogs be sterilized before going to their new homes.

Spay (Ovariohysterectomy, OHE, neuter)

Dog Spay

This is the surgical removal of part(s) of the female reproductive system - ovaries and uterus from a dog or cat. It is normally performed simultaneously. It can be done electively or because of diseases of the ovaries, uterus, vagina or systemic diseases.

Elective use:

  1. Prevention of estrus.

  2. Control of breeding by sterilization.

  3. Prevention of mammary neoplasia (breast cancer) if performed early - preferably before the first heat.

  4. Reduced prevalence of acquired inguinal hernias.

Ovarian disease

  1. Neoplasia Ovary (ovarian cancer)

  2. Abnormal estral cycles (heat cycles) - prolonged pro-estrus and estrus.

Uterine disease - non-gravid

  1. Cancer of the uterus

  2. Pyometra/cystic endometrial hyperplasia (CEH) - infection of the uterus.

  3. Acute metritis (inflammation of the uterus).

  4. Hemometrium.

  5. Subinvolution of placental sites.

Uterine disease - gravid

  1. Prolapse of the uterus.

  2. Torsion of the uterus.

  3. Rupture of the uterus.

  4. Fetal death/mummification/maceration/dystocia - complicated delivery.

  5. Abortion / stillbirth.

Vaginal disease

Systemic disorders

Female Pitbull Terrier with Mange Mites

Advantages of Spay

  1. It is a relatively safe procedure.

  2. Significantly reduces the incidence of mammary gland tumours (the most common kind of cancer in dogs) if performed early.

Disadvantages of Spay

  1. May predispose to urinary incontinence

  2. May predispose to obesity.

Dog castration

Castration refers to the surgical removal of the male reproductive system - the testicles.


  1. Inhibition of male fertility and associated behavioural responses.

  2. Treatment of certain diseases influenced by male sex hormones, eg prostatic diseases/cancers, Anal glands diseases and cancers (perianal adenomas/adenocarcinoma) and perineal hernias.

  3. Treatment of testicular cancer (neoplasia).

  4. Treatment of inflammation of the testicles (Orchitis/epididymitis).

  5. Treatment of genetic abnormalities or problems, eg abdominally retained testicles (cryptorchidism).

  6. Treatment of trauma to the male genital region.

  7. Treatment of certain endocrine (hormone) conditions.

  8. Occasionally as part of the treatment to control idiopathic epilepsy.



Watts J (2018) The use of bipolar electrosurgical forceps for haemostasis in open surgical ovariectomy of bitches and queens and castration of dogs. Journal of Small Animal Practice 59 (8), 465-473.

Sundburg, C. R., Belanger, J. M., Bannasch, D. L., Famula, T. R., & Oberbauer, A. M. (2016). Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study. BMC veterinary research, 12(1), 1-10.

Leitch, B. J., Bray, J. P., Kim, N. J. G., Cann, B., & Lopez‐Vilalobos, N. (2012). Pedicle ligation in ovariohysterectomy: an in vitro study of ligation techniques. Journal of Small Animal Practice, 53(10), 592-598.

Ball, R. L., Birchard, S. J., May, L. R., Threlfall, W. R., & Young, G. S. (2010). Ovarian remnant syndrome in dogs and cats: 21 cases (2000–2007). Journal of the American veterinary medical association, 236(5), 548-553.

Miller, D. M. (1995). Ovarian remnant syndrome in dogs and cats: 46 cases (1988–1992). Journal of veterinary diagnostic investigation, 7(4), 572-574.

Wallace, M. S. (1991). The ovarian remnant syndrome in the bitch and queen. Veterinary Clinics of North America: Small Animal Practice, 21(3), 501-507.

Fingland, R. B., Waldron, D. Ovariohysterectomy. In: Bojrab MJ,

WaldronDR, Toombs JP, editors. Current techniques in small animal surgery. 5th ed. Jackson, WY: Teton NewMedia; 2014. p. 516–21

Johnston, S. A., Von Pfeil, D. J. F., Déjardin, L. M., Weh, M., & Roe, S. (2012). Internal fracture fixation. Tobias KM, Johnston S. Veterinary Surgery: Small Animal. St. Louis: Elsevier Saunders, 576-607.

Dawson, L. (2016). Development and evaluation of a canine and feline welfare assessment tool for use in companion animal veterinary clinics (Doctoral dissertation).

Hedlund, C. S. (2002). Surgery of the reproductive and genital systems. Small animal surgery.

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