For decades, early spay and neuter (also known as sterilisation) have been championed as essential parts of responsible dog ownership. Backed by strong public health goals, from population control to disease prevention, sterilisation has become a near-automatic procedure in both shelters and private homes, often done before a dog reaches six months of age.
But as our understanding of canine development, hormones, and welfare deepens, so too does our view of when, and even whether, to neuter in every case.
In 2025, progressive vets are urging a more nuanced approach. It’s no longer a one-size-fits-all decision. Instead, age, breed, sex, lifestyle, and welfare outcomes all matter, and the old blanket policies may be doing some dogs more harm than good.
Why early neutering was popular
Historically, early sterilisation was promoted to:
- Prevent unwanted litters
- Reduce roaming and aggression
- Lower risk of reproductive cancers (e.g. mammary tumours)
- Simplify procedures with less bleeding and faster recovery in young animals
And, in South Africa, where street dog populations, shelter overcrowding, and zoonotic diseases remain major challenges, early neutering remains vital in many high-risk, underserved communities.
“In public sector work or township outreach, we absolutely still support early sterilisation,” says one vet, who works with community animal clinics in Gauteng. “It’s a matter of preventing suffering, not just individual outcomes.”
What the new research shows
But outside of population control contexts, a growing body of evidence is questioning whether early sterilisation is always the best choice, especially for owned pets and working dogs.
Hormones like oestrogen and testosterone do more than control reproduction. They play a crucial role in bone growth, muscle development, behaviour regulation, and immune system maturation.
Studies have linked early spay and neuter (under six to twelve months) with:
- Higher risk of joint disorders (hip dysplasia, cranial cruciate ligament rupture)
- Increased risk of certain cancers (osteosarcoma, hemangiosarcoma, lymphoma – especially in larger breeds)
- Greater likelihood of urinary incontinence in spayed females
- Higher incidence of anxiety and noise phobias, particularly in neutered males
Essentially, research is showing that hormones play a role in some cases in helping a dog become stable, both physically and emotionally. For some dogs, removing the hormonal influence too soon can create other issues.
So, when should you neuter?
That depends.
Size matters
- Small-breed dogs (under 15kg) mature earlier and are less prone to hormone-related joint issues. Spaying/neutering between six to nine months may still be appropriate.
- Medium and large-breed dogs mature more slowly. Waiting until 12–18 months after growth plates have closed may reduce the risk of orthopaedic disease.
Purpose matters
- Working dogs or dogs with known anxiety may benefit from delayed neutering to support optimal physical and behavioural development.
Environment matters
- In high-risk environments (e.g., township dogs, free-roaming dogs, shelters), the risks of not neutering often outweigh the potential downsides of neutering at an early age.
Sex matters
- Female dogs are often spayed before their first heat to reduce the risk of mammary tumours, but some research now supports waiting until after one heat in certain breeds.
- Male dogs may benefit from staying intact for longer periods, particularly in terms of muscle mass and joint stability.
The South African balancing act
South Africa straddles two very different dog worlds. This creates a welfare tension: what is best for population control isn’t always what is best for an individual dog’s long-term health.
The most ethical decision is the informed one, so talk to your vet and understand the risks and benefits involved.
What to ask your vet
Before booking your dog’s sterilisation, ask:
- What’s the best timing for my dog’s breed and lifestyle?
- Are there medical reasons to do it earlier or later?
- What are the behavioural considerations for this specific dog?
- Can I monitor my female dog safely through a heat if we wait?
The answer is individual
There’s no universal answer. Neutering remains a vital welfare tool — especially in South Africa, where unwanted litters lead directly to suffering and death. But early-age sterilisation should not be automatic for every dog, especially in private ownership.
Instead of asking, ‘When should I neuter?’, it’s better to ask: ‘What’s best for this individual dog’s long-term health and wellbeing?’
