MV Root Kustritz 2012
Surgical sterilization of dogs and cats is a well-accepted measure for population control in some countries, but is considered unethical as an elective surgery in other countries. This is a review of what is known regarding positive and negative effects of gonadectomy surgery on individual animals and on societal management of unowned dog and cat populations.
Elective gonadectomy, castration in males and either ovariectomy (OV) or ovariohysterectomy (OHE) in females, is the most common small animal surgery performed in some countries and is unethical or illegal in other countries (Salmeri et al. 1991b; Gunzel-Apel 1998; Greenfield et al. 2004). There is no question that we alter animals when we perform gonadectomy. This is a review of the specific changes associated with gonadectomy in dogs and cats and the evidence we have for cause-and-effect. Thorough reviews of the literature have been published (Root Kustritz 2007, 2010; Reichler 2009).
Some recognized reasons for the promotion of gonadectomy and some stated concerns are societal in nature, some refer to populations of animals, and some are pertinent to health of individual animals. Veterinarians are encouraged to help clients and those who write public policy to understand which aspect is being addressed when specific recommendations for gonadectomy are being made. There also is great variability in number of studies supporting some of the findings described, and veterinarians are encouraged to be aware of the amount of evidence to support any given claim. Finally, breed predispositions exist for some of the concerns described and must be included in decisions about suitability of gonadectomy in a given animal.
Advantages of gonadectomy include decrease in reproductive tract disease, including pyometra and mammary neoplasia in bitches and queens, and testicular neoplasia and prostate disease in male dogs. Other advantages include: decrease in pregnancy and parturition-related disorders including metritis, mastitis and dystocia; decrease in hormone-associated disorders such as vaginal prolapse in bitches and mammary hypertrophy in queens; and decrease in undesirable sexual behaviours (Romagnoli 2008). Disadvantages of gonadectomy include surgical and anaesthetic complications, increased risk of neoplasia of various organ systems, increased incidence of some musculoskeletal and endocrinologic disorders, obesity and urinary incontinence in bitches. All of these will be described in more detail. This discussion incorporates early spay-neuter, defined as gonadectomy at 8–16 weeks of age (Root Kustritz 1999), and gonadectomy at any age after 16 weeks.
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