Desexing (surgical sterilisation) of companion animals


Surgical desexing (sterilisation) is an important tool to reduce unwanted companion animals in the community, particularly when combined with relevant community education programs.


Desexing includes the surgical procedures of ovariohysterectomy or ovariectomy in females and castration (orchidectomy) in males. These are major procedures and the skills, equipment and facilities used should be of sufficient standard to reflect the needs of the animal. The surgeon should have the necessary competence and experience to perform the procedure. Veterinarians should ensure that all appropriate precautions are taken to minimise the risks of anaesthesia, surgery, stress and infection to animals when undergoing desexing procedures

Compulsory desexing of privately owned animals has not been shown to substantially reduce the unwanted dog and cat population. However the desexing of unowned animals prior to rehoming is supported. Physical containment of the animal in oestrus is not recommended as an alternative to desexing, and non-surgical means of fertility control are not currently suitable long term alternatives to surgical desexing.

Benefits of desexing
Desexing helps control companion animal populations and may have behavioural and health benefits. It is currently the only widely available effective and permanent method of preventing breeding.

Desexing can reduce behavioural problems such as free-ranging and some aggressive behaviour, which can cause public nuisance. In cats, desexing stops calling behaviour in queens, reduces spraying in toms, reduces fighting, abscesses and transmission of infectious diseases.

It is commonly accepted that desexed females have a greatly reduced incidence of mammary neoplasia although this requires more robust substantiation. Diseases of the ovaries and uterus are eliminated, however evidence suggests that bitches desexed prior to 20 weeks of age may have a statistically increased incidence of urinary incontinence compared to those desexed later9. Testicular tumours in males are eliminated, and there is a reduced incidence of prostate disease, perianal tumours and perineal hernias.

Age of desexing

Veterinarians must decide the appropriate age of desexing based on current scientific evidence, and consideration of the animal’s weight, vaccination status, health status and ability to withstand major surgery. At the veterinary practitioner’s discretion, desexing can be performed from as early as 8 weeks of age and at a minimum of 1kg bodyweight..

Veterinarians should recommend desexing of companion animals before puberty unless there is a valid reason to delay the procedure.  The traditional age of desexing was 6 months of age however earlier desexing is now recommended based on: new information on the safety of early age desexing; failure to comply by a percentage of owners at 6 months (including failure to redeem discount certificates); and puberty being possible prior to this age in a percentage of dogs and cats. Results of a survey of Australian veterinarians in 2014 demonstrated a preference towards traditional age desexing, but a willingness to perform desexing earlier in some situations. Desexing before 6 months of age is commonly undertaken in the shelter situation.

A 2012 survey2 identified that participating veterinarians had already reduced their age for desexing cats to on average, 3.4 months for queens and 3.2 months for toms. Early age desexing is particularly important for cats, which may be able to reproduce from 4 months of age.

There are advantages and risks of early age desexing. Recorded side effects include infantile external genitalia, and in dogs, delayed growth plate closure and potential for associated orthopaedic conditions (angular limb deformities, hip dysplasia, cranial cruciate ligament L disease).There is a statistically increased risk of urinary incontinence in the bitch if desexed before 20 weeks of age. Benefits include a faster surgery time, lower anaesthetic dose and faster healing1.

Desexing as a population control measure
The success of sterilisation as a population control technique depends on the percentage of animals desexed and the freedom of those remaining intact. It is unlikely to succeed as a single measure. Up to 90% of breeding animals must be desexed to halt population increases8.

Public attitudes to desexing
Opinions on desexing vary, but data suggests objection to desexing is in the minority with one survey study showing 78% of owned dogs and 93% of owned cats are desexed5.

Problems with compulsory desexing of companion animals

There are inherent problems with the concept of compulsory desexing. Successful enforcement of compliance would depend on universal registration and permanent identification, which have already proven difficult to enforce. Evidence suggests that, at least for cats, compulsory desexing of owned animals would have little effect on the cat population as the majority of over-supply emanates from the semi-owned and unowned populations7.

Subsidised desexing schemes
Recent economic analysis suggests that low cost desexing schemes are effective at raising total community desexing rates, but may have no clear impact on reducing the number of euthanasia cases4 and must be assessed over a long period3.

Desexing in animal shelters
For animal shelters, desexing animals is influenced by commercial and legislative factors. However, an animal’s welfare should not be diminished in the short or the long term by desexing age, facilities or technique. Animal shelters should keep statistics on desexing status and desexing outcomes for shelter animals.


  • 1. RSPCA Australia (2012) Research Report: Early Age Desexing,
    Searched 17 January 2013

    2. Farnworth MJ et al. (2012) Veterinary attitudes towards pre-pubertal gonadectomy of cats: a comparison of samples from New Zealand, Australia and the United Kingdom NZ Vet J(12) access via Searched17 Jan2013.

    3. Frank J M (2002) The Actual and Potential Contribution of Economics to Animal Welfare Issues. Society I Animals 10: 4 Accessed at
    Searched 17 Jan 2013

    4. Frank J M and Carlisle-Frank P L.(2007) Analysis of programs to reduce overpopulation of companion animals: Do Adoption and low-cost spay/neuter programs merely cause substitution of sources? Ecol. Econ.(62)740-746

    5. Headey B. (2006) National People & Pets Survey. Published by Australian Companion Animals Council.

    6. Leung V (2014) The View of Australian Veterinarians on the Age of Desexing of Dogs and Cats. Honours Dissertation University of Sydney.

    7. Marston L et al (2006): Cat Admissions to Melbourne Shelters, Report to Bureau of Animal Welfare. Dec2006.Access at
    Searched 17 Jan 2013

    8. Nasser R, Mosier J(1991).Projections of pet populations from census demographic data. J Am Vet Med Assoc 198:1157–1159

    9. Spain CV, Scarlett JM and Houpt KA (2004). Long-tern risks and benefits of early-age gonadectomy in dogs. J Am Vet Med Assoc 224: 380-387

Date of ratification by AVA Board 3 November 2015

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