Optimum Age for Sterilisation of Dogs

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In a country where companion animal overpopulation, and the associated suffering, is commonplace it is not the intention of AHAH to advise no sterilisation. It is our place to question the current trend of very early sterilisations. In welfare situations with poor client compliance sterilisation at a very young age may be necessary. When considering dogs and cats placed in homes with responsible guardians early spay and neutering may not be in the best health interests of your companion.

Sex hormones have a structure similar to anabolic steroids. These hormones are necessary for optimum growth, skeletal and muscular development and are required until closure of

growth plates. In dogs, all growth plates are closed at 14 months of age. Sex hormones promote the closure of growth plates at puberty so bones of dogs and bitches sterilised before puberty continue to grow. These dogs are taller evidenced by their longer limbs. They have a lighter bone structure because sex hormones are critical for achieving peak bone density. These dogs also have narrow chests and skulls. Should you consider any form of sport or strenuous exercise with your dog, recent research shows that early sterilisation predisposes your dog to injury of the cruciate ligament and may increase the expression of hip dysplasia.

There is evidence that sterilising a bitch before her first season will reduce the incidence of mammary tumours but there is also evidence that shows that early sterilisation of dogs increases the chances of developing bone cancer and haemangiosarcoma. Both of these forms of cancer are life-threatening whereas 30% of mammary tumours are malignant. Vigilance and examination will expose mammary tumours very early on in their development thereby allowing for surgical removal and a good prognosis. Haemangiosarcomas usually affect spleen, liver and heart and can be viewed as a silent killer. Bone cancer (osteosarcoma) is aggressive with little chance of cure by the time vets are able to diagnose it.

Neutering has long been advised to solve problems of aggression. There is little evidence to support its efficacy in this regard. Recent research shows that dogs sterilised at an early age have a higher tendency to develop noise phobias and other behavioural issues. Urinary incontinence is a common result of early spaying. One study showed an increased prevalence of hypothyroidism in canines neutered at an early age.

This blog is designed to ask questions about routine practice. More research needs to be conducted, and is being conducted, into the long term effects of pre-pubertal gonadectomy. Each animal and home situation should be seen as unique, and a decision to sterilise based on these specific circumstances.

Table taken from The Agility Advantage Chris Zink DVM

References available on request.

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