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De-sexing your pet

The appropriate age to de-sex your pet doesn’t have a black and white answer. For most pets, the traditional age of six months is likely to be appropriate. In some cases it may be better to delay de-sexing until after puberty (around 10-12 months in large breeds, 18 months in giant breeds). Below is some information from the New Zealand Veterinary Association with regards to de-sexing

Age of de-sexing
Accounting for both the known benefits and potential risks associated with de-sexing, the NZVA recommends:

Due to the complex nature of potential risks and known benefits associated with de-sexing in dogs, no single recommendation is appropriate for all dogs.
For the majority of dogs that aren’t intended for breeding and are fit to undergo anaesthesia, pre-pubertal de-sexing of dogs is appropriate (i.e. de-sexing at around six months old).
There are however, specific populations of dogs, in which breed, genetic predisposition and lifestyle factors suggest delaying de-sexing until after puberty may provide a health benefit.

Benefits of de-sexing
Research reveals that de-sexed animals live longer lives. No unplanned pregnancies is a definite benefit also. De-sexing will benefit individual cats and dogs by:

  • Eliminating the risk of uterine infections in females. Around 25% of female dogs can be expected to experience pyometra by ten years of age if not de-sexed.
  • Eliminating all diseases associated with pregnancy and parturition.
  • Eliminating the risk of developing tumours associated with the testes, ovaries or uterus.
  • Protecting against development of other types of tumour such as vaginal leiomyomas in female dogs and reducing the risk of hepatoid gland adenomas in male dogs.
  • Reducing injuries related to roaming and aggressive behaviours (e.g. traffic accidents and fight wounds). Male entire cats have a higher prevalence of feline immunodeficiency virus infection than de-sexed cats due to a predilection for fighting.
  • Providing protection against the risk of developing mammary tumours in female cats and dogs if de-sexed before the third oestrus cycle. The highest level of protection was achieved in those cats and dogs de-sexed pre-pubertally (i.e. before the first heat).

De-sexing cats and dogs will also provide benefits to their owners:

  • Cats and dogs are less likely to require veterinary treatment for injuries related to roaming and fighting.
  • Eliminating undesirable behaviours associated with hormonal cycling in female cats and dogs (e.g. attracting other cats and dogs to the house, vaginal bleeding and “calling cats”).
  • Male cats and dogs display reduced urine marking in the house, humping, and roaming behaviours.
  • Council registration fees for de-sexed dogs are often lower.
  • Unpleasant odours associated with male cats are eliminated.
  • Admission to doggy day-care facilities, boarding kennels and catteries usually require cats and dogs to be de-sexed.
  • Surgery on pre-pubertal animals is often technically less demanding than those that are fully mature, and is associated with lower costs, lower surgical complication rates and more rapid recovery.


Negative effects associated with de-sexing

Obesity is a major health problem in companion cats and dogs in New Zealand. De-sexing cats and dogs has been associated with reduced metabolic rates and weight gain. The risk of weight gain is not a contraindication to de-sexing as it can be simply managed.

Cranial cruciate ligament rupture in large-breed dogs
There is some evidence that suggests delaying de-sexing in large breed dogs, (in particular golden retrievers), until after growth plates are closed (i.e. around 12 months old) may reduce the future risks of rupturing cranial cruciate ligaments in the knee.

Urinary incontinence in female dogs
There is weak evidence that supports a possible link between urinary incontinence and de-sexing female dogs. The risk of incontinence may be higher in dogs that were de-sexed at a younger age. Delaying de-sexing until after 16-20 weeks of age, particularly in large breeds may reduce the risk of developing urinary incontinence.

Hip Dysplasia
Some studies suggest that pre-pubertal de-sexing may cause worsening of pre-existing hip dysplasia; however as hip dysplasia is a complex disease with genetic and environmental factors, it isn’t known as yet how strong this evidence is.

There is some evidence that certain tumours (such as osteosarcomas) may be more common in de-sexed pets. This should be weighed against the reduced risk of other tumours that de-sexing provides.