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Desexing your pet is a surgical procedure that prevents them from being able to reproduce. This is the most frequent surgery performed by our vets, and generally your pet is home by the evening of surgery.

When to desex?

We often get asked this by puppy owners and it is a good question, because age at desexing can potentially have an impact on your dog's development. 


Historically people used to recommend desexing dogs around 6 months of age, but there is emerging evidence that this may be inappropriate for some dogs.


At Mullum Vet Clinic the vets have recently reviewed the most up to date evidence for the ideal time of desexing across each breed. It's a complex area but here is a brief summary.


The first thing to mention is that desexing isn't necessary for every dog; for instance those planned for breeding. However desexing provides some important benefits including :

  • Eliminating the risk of pyometra, a life-threatening infection of the uterus that can occur in undesexed female dogs.

  • Reducing risk of mammary cancer in female dogs.

  • Reducing risk of prostate overgrowth in older male dogs, which can cause difficulties with defaecation/ hernias/ infection.

  • Eliminating the risk of other diseases of the genitourinary tract, testicles or ovaries, such as tumours or torsions

  • Eliminating the risk of unplanned pregnancies.

  • Reduction in unwanted sexual behaviours such as roaming, mounting, humping and urine marking.

  • Reduction in aggression between male dogs.

  • Reduction in surrender of unwanted puppies to shelter societies.




Dogs reach sexual maturity in the range 6-24 months of age but for most breeds usually between 7-12 months of age. Larger breed dogs tend to mature physically and sexually more slowly than smaller breed dogs. For most small breeds of dog we recommend desexing around 5.5 - 6.5 months. This is before they hit puberty but still gives them adequate time for development. 

An important exception are dachshunds. Studies have shown a potential link between desexing too early and increased risk of inter-vertebral disc disease, a spinal problem that this breed is particularly prone to, that causes debilitating weakness and paralysis. For this reason we recommend letting female dachshunds go through 2 heats before being desexed, and waiting similarly until >2years old for males, or even considering leaving them entire. 


Female dogs with a "hooded" vulva that is recessed up within the skin should also ideally be allowed to have one heat before desexing, as this may help enlarge the vulva and make it less "hooded". A vet can advise you whether this is an issue for your dog.

For medium-sized breeds of dog we recommend you speak to your vet about the ideal time of desexing. Many can be done in a similar time-frame around 6-7 months old, but in some cases it's better to allow the dog to go through puberty before desexing. 

One particular type of dog that should not be desexed before the onset of puberty are female collies and border collies, as these dogs are prone to developing urinary incontinence later in life if desexed too early. Allowing at least one heat may reduce the incidence of this problem.


For most large breeds of dog we recommend delaying desexing until they are sexually mature, so generally at over 1 year of age. This is largely because they reach puberty at a later age & tend to be more prone to diseases of the limbs, joints, ligaments and bones, so allowing more time for development of these structures is beneficial.


There is limited but growing evidence that in all breeds early desexing may be linked with increases in certain serious diseases including cruciate ligament tears, hip dysplasia and some cancers. However it is worth noting that veterinary scientists are still not 100% sure of these particular links as there may be confounding factors confusing the picture. For example the higher observed disease rate may actually be due to other factors such as being overweight, which is more common in desexed than entire pets. Nonetheless, as a precaution we are now tending to recommend desexing later than we used to in decades past, certainly not before 5-6 months of age.


We strongly discourage the practice of some breeders whereby they have their puppies desexed very early around 2 or 3 months of age, which unfortunately we see with some frequency.


It is important to realise that when we desex our pets it does reduce their metabolic rate, which is the speed at which the body burns through calories. For this reason we must feed about 25% fewer calories once desexing has been performed.  So make sure you adjust your pet's diet appropriately after desexing so they don't stack on the pounds! This may mean simply reducing the amount of food given at each meal, or may mean adding in more low-fat foods (vegetables, lean meats, prescription low-fat high-fibre kibble) and reducing the high-fat foods (treats, bone marrow, chicken necks, mince, cheese, and carbohydrates including rice, pasta and potato). 


Of course in addition we also recommend switching from puppy food to adult food at the end of adolescence, to account for the natural decrease in energy needs once the growth phase has finished.


If you have any questions about desexing or your puppy in general don't hesitate to call us on 02 6684 3818, so we can help you set up a long, happy and productive life for your pet!



 Abbie Tipler ATCL  BVSc MANZCVS @ VSS, "Desexing & Associated Risk

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