castration

Many things changed this year, the way we work, how we socialise and our ability to travel.   For veterinary clinics, the “Covid Puppy” has created a large influx of new pet owners and new puppies, with all the questions that entails.  I hope to cover why we desex, when should we desex and whether it is truly necessary.   Click here for the Short Answer

Why do we desex?

The obvious answer here is we don’t want puppies or kittens, but there are other reasons to consider.

Behaviour

Intact male dogs and to a lesser extent female dogs – when they are “in season” have a basic physiological drive to reproduce.  This leads them to do some pretty silly stuff – jump fences, run across busy roads, get into fights.  ( I will point out that humans are no different – just head into the city on any Saturday night).  These behaviours have a significant risk factor for death or severe injury.

Disease

There are certain diseases that I don’t think there is any doubt that desexing removes or drops that risk to zero.

• Testicular Cancer – you can’t get it if you don’t have it – same goes for Ovarian Cancer in female dogs.
• Mammary Cancer – ie Breast Cancer – there was a study done comparing dogs in the UK and dogs in Sweden.  The study from Sweden looked at causes of mortality in 80,000 dogs and found that their population had an incidence rate 7.7 times higher than the incidence rate of female dogs in the UK.
• Pyometra ( Uterus Infection ) –  A study of approximately 200,000 Swedish dogs (a country with a low overall sterilization rate) reported an overall incidence of pyometra at 2% and also found that approximately 24% of female dogs experienced pyometra by 10 years of age.  The incidence in desexed dogs is 0%.
• Prostate Disease -Benign prostatic hypertrophy-hyperplasia is a common disorder in sexually intact male dogs. 95-100% of entire male dogs will have prostatic enlargement once they reach 9 years of age. In addition, BPH predisposes dogs to prostatitis.  Neither BPH nor prostatitis is commonly associated with substantial morbidity, and castration is an integral part of the treatment of both conditions.

When should my Pet be desexed?

Short Answer

1. If you are looking to avoid behaviour problems and keep your life simple – 5-6 months of age, but please be aware we now recommend 12 months plus.
2. If you want to ensure your pet’s full development potential 12 months + of age.
3. For some breeds 2 years or more.

There are benefits to each of these viewpoints such that neither is wrong but if you are looking for a more in-depth answer read on.

Long Answer

History

Historically desexing our pets became common about 50 years ago – when it was recognised that a large number of unwanted and stray dogs were causing problems around large cities.  At that time the recommendation was to perform the procedure at or around 6 months of age.    Several factors weighed into this timing but by far the most overwhelming was that female dogs will generally experience a season before 7 months of age.  Female dogs are entirely capable of falling pregnant on this first cycle so the view was desex before this could happen as far as male dogs went – they got dragged along for the ride.

In the 90’s, pet ownership and the stray dog problem persisted and Animal Protection Societies became involved in the care of many puppies and kittens.  The policies at this time led to a push to introduce early-age desexing – where the procedure was performed as young as 8 weeks of age.  People felt it was more important the get the pets desexed than to rely on owners returning an older pet and desexing them later.  Smaller animals were also easier to manage in terms of size and also the inherent costs involved were lower.

Moving into the 21st century, new ideas emerged that became more focused on what was best for the individual dog, we had more data from the previous 50 years which we could use to gauge the positives and negatives of our various choices.  Now some vets are recommending a late age desexing – which allows the pet to mature with its natural hormone balance intact. In some countries desexing is banned.

In summary, there is not a straightforward answer or a 1 size fits all solution.  Different people have different goals and targets.

Where are we now?

We now understand that puppies and kittens have a lot of development to do after they are born, various organs mature at different speeds.  The skeletal and muscular growth can take as long as 2 years in large breed dogs and as short as 8 months in small breed dogs.   Kidneys also mature at a different rate – kidney maturity we think is pretty much complete at about 200 days of age thats about 6.5 months.  The majority is completed in the first 4 months – you can see this as your pet’s toilet training pretty much improves dramatically at this age.  They can hold it for the night!  The same applies to liver development – while no specific animal studies could be found.  In humans, full maturity can take up to 2 years following birth.  Given this knowledge, the advice has to be that we should try and avoid anaesthesia until these vital organs are mature.

Your vet will probably suggest a blood test prior to anaesthesia to confirm the healthy and optimal function of these organs at the bare minimum it’s important to realise the test doesn’t tell you they are fully mature only that they are not diseased.

The previously mentioned disease risks mean we should still desex but perhaps we need to show more consideration for age.

For Male Dogs – these guys can probably wait until 12 months of age  – this will allow a stronger skeletal structure and more robust physical appearance –  for the larger breeds – it may also reduce the incidence of bone cancer.

For female dogs – I would probably desex them at 5-6 months of age – dealing with a dog on heat is often a lot to handle in a busy family with an inside dog – but you are welcome to delay until around 12 months of age – after the first season.  This may reduce the risk of incontinence later in life. 

I will categorically say I don’t believe in early-age desexing – I see no benefit to the individual dog or the dog’s lifelong owner.

Spay or Spey

The correct term is spay and it means to remove the ovaries and uterus in a female dog.  That being said as with all languages the alternative spelling spey does get used here in Australia.  You won’t find either term common to the layperson in the USA.

References

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Beath SV. Hepatic function and physiology in the newborn. Semin Neonatol. 2003 Oct;8(5):337-46. doi: 10.1016/S1084-2756(03)00066-6. PMID: 15001122.

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