How old does my dog need to be to be desexed (speyed/neutered/castrated)? | Companion Animal Veterinary Hospital
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How old does my dog need to be to be desexed (speyed/neutered/castrated)?

Matt Young's picture
Matt and Lachie desexing a puppy

First of all a couple of definitions:

Castration is the desexing of a male dog by removal of the testicles, sometimes this is referred to as neutering

Spey is the desexing of a female dog or bitch when the ovaries and uterus are removed. 


  • Pups (both male and female) should be at least 8 - 10 weeks of age
  • They need to be at least 1kg in body weight
  • The testicles in male pups need to be descended and in the scrotum to castrate them
  • The pups should be in good health and body condition


  • sick animals
  • cryptorchid or monorchid dogs (if the testicles aren’t descended it is better to wait. Testicles can still come down up to 6 months of age and it is far easier to desex them if they are in the scrotum)

Some history of why we do it when we do

Traditionally we have desexed animals at 5-6 months of age. Why? Because at this age we are likely to be desexing them before they become sexually mature (reach puberty). This will prevent unwanted pregnancies which is our main aim with desexing.

In the last decade or so desexing animals earlier than this has become more common. The reason for doing animals earlier has been that animal welfare organisations wanted to desex the animals prior to being rehomed. Prior to early age desexing people were given a voucher for desexing which was not very effective (less than 60% of vouchers were redeemed).

Is desexing younger pups safe?

Yes, anaesthetising and desexing young puppies is safe if the correct protocols are followed and they are monitored while under the anaesthetic.

Young puppies:

  • can’t be starved for long periods prior to anaesthesia as their blood sugar levels drop too low (they are only fasted for 2-3 hours prior to surgery)
  • don’t control their body heat well (we supply artificial warmth sources as soon as they are premedicated and throughout surgery until they are recovered)
  • need to have their heart rate carefully controlled to ensure they have enough blood being outputted from their heart (a veterinary nurse monitors your pup until they are completely recovered)

There are some advantages to desexing them at this age:

  • there is less fat around the organs so less chance of bleeding and quicker surgery
  • wounds heal faster
  • the wounds are smaller
  • they won’t be on heat so there is a lower risk of bleeding and trauma.


Potential Problems

The have been some studies in recent years that have looked at potential problems or disadvantages to desexing animals younger than the traditional 5-6 months of age.

Urinary incontinence

Some desexed female dogs dribble urine when they are resting or asleep. This can happen quite a few years after the surgery. Desexing is definitely involved in the development of urinary incontinence, however the exact mechanism that causes it is unknown. Many dogs respond to low dose oestrogens but this is because the oestrogens have an effect on the bladder neck and increase the tone of the bladder neck, not because the hormones are lacking.

Desexing prior to 3 months may increase the risk of urinary incontinence compared to those desexed between 3 and 6 months of age.

Hip dysplasia

According to 1 study there may be an increased risk of hip dysplasia in dogs desexed prior to 5.5 months of age. This was a very small increase in risk and there was also a much lower rate of dogs euthanaised because of their hip dysplasia in dogs desexed prior to 5.5 months. Other studies have not shown any increased risk of hip dysplasia at all.

Recently there have been studies of golden retrievers and labradors which have used limited populations of dogs and the results found can’t be extrapolated to the rest of the population.

Overall, yes there may be a very minimal increased risk of hip dysplasia but it’s not significant in my opinion when weighed up against the other advantages to desexing early.


Yep, desexed dogs are prone to becoming overweight. They do have reduced energy requirements compared to non-desexed animals. Interestingly the younger they are desexed the less likely they are to be overweight.

So what is the best age to desex?

So based on all this and weighing up the pros and cons the following are my recommendations for the best age to desex a male or female dog:

  • For pups being rehomed from welfare organisations such as WARN- desex at 8-10 weeks
  • For pups that already have their forever home- desex them as soon as the vaccinations are complete (usually finalised at 14-16 weeks)

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