De-sexing your puppy

The decision to de-sex your puppy is a responsible and sensible one to make.  Some debate exists about the right age to carry out surgery.  Recent studies have been carried out to determine the safest, most beneficial age to neuter pets. 

Neutering male dogs reduces the urge to fight and stray and can make them easier to train.  It also provides protection against prostatic and testicular cancer.  The surgery can be done at any age from four months onwards.  Careful attention to diet and exercise will control potential weight gain.  Any dog used for stud should be an exceptional example of his breed. 

The timing of speying bitches is a little trickier.  Speying prior to puberty prevents unwanted pregnancies, protects against breast cancer and uterine infection.  It is also a quick, easy surgery with a short recovery time.  However, there is an increased tendency to develop urinary incontinence, especially when very early surgery is done.  We recommend waiting until at least six months to spey your bitch.  We don't like to spey during the ‘heat' period due to increased bleeding but can perform surgery in early pregnancy.  If you are considering breeding from your bitch, please seek advice from your vet regarding her suitability, age and health.  It is a serious and demanding task to raise a litter of healthy puppies - planning is the key to success!  

For most pets, de-sexing is a safe procedure and leads to a healthier pet who is easier to look after and a joy to own.   

Age and benefits of de-sexing 

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 case 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.

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

  1. 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).
  2. 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.

Research reveals that de-sexed animals live longer lives. No unplanned pregnancies is also a definite benefit. 

De-sexing will benefit individual 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).
  • Providing protection against the risk of developing mammary tumours in females if de-sexed before the third oestrus cycle. The highest level of protection was achieved in those females de-sexed pre-pubertally (i.e. before the first heat).

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

  • They are less likely to require veterinary treatment for injuries related to roaming and fighting.
  • Eliminates undesirable behaviours associated with hormonal cycling in female dogs (e.g. attracting other dogs to the house, vaginal bleeding and “calling cats”).
  • Male dogs display reduced urine marking in the house, humping, and roaming behaviours.
  • Council registration fees for de-sexed dogs are often lower.
  • Admission to doggy day-care facilities and boarding kennels usually require 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 dogs in New Zealand. De-sexing dogs has been associated with reduced metabolic rates and weight gain. However, 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 females:

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. 

Although the negative effects of de-sexing may seem frightening, the positives certainly outweigh the negatives. With rising stray animal numbers in New Zealand, de-sexing your puppy when they reach the right age is one of the most responsible things you can do as a pet owner.

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