When it comes to neutering (castrating) male dogs, the timing can affect your dog’s long-term health, behaviour, and physical development. We’re often asked for guidance—but while we can share evidence and explain our organisational policy, it’s important to note:
We are not vets and do not provide individual advice on neutering.
Instead, here’s a balanced, research-informed overview of the pros and cons of neutering at different ages—and the reasoning behind our approach for assistance dogs.
Neutering Before 9 Months
Pros:
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Eliminates the risk of testicular cancer.
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Prevents unwanted pregnancies, especially where dogs may come into contact with in-season females.
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May help reduce sexually driven behaviours like roaming, urine marking, and mounting (though not always).
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Can reduce the risk of certain prostate issues later in life.
Cons:
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Increased risk of joint disorders in large and giant breeds (e.g. hip dysplasia, cranial cruciate ligament injuries) due to hormonal impact on growth plate closure.
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Possible link to anxiety or fear-based behaviours in some dogs, particularly in sensitive or noise-reactive breeds.
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Increased risk of certain cancers (e.g., osteosarcoma, hemangiosarcoma) in some breeds, based on current studies.
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May limit the development of muscle mass and bone density due to early loss of testosterone.
Neutering Between 9 and 18 Months
Pros:
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Reduces risk of testicular and some prostate conditions.
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May still reduce sexually motivated behaviours, especially if they haven’t become deeply habitual.
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Allows more time for physical development, especially for medium and large breeds.
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Potentially more stable behavioural outcomes compared to neutering before 9 months.
Cons:
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Still some risk of orthopaedic issues if growth plates are not fully closed.
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Behavioural responses to neutering vary—some dogs may become more anxious or reactive, while others show no change.
Still risk of accidental mating's.
Neutering Between 18 Months and 2½ Years
Pros:
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Allows for full hormonal and skeletal development, potentially supporting joint health and emotional maturity.
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You can more easily distinguish hormone-driven behaviours vs. learned behaviours before making a decision.
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Reduces risks of testicular cancer and helps prevent some prostate-related issues.
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Less likely to result in negative behavioural changes, especially in confident, mature dogs.
Cons:
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Risk of testicular or prostate disease slightly increases with prolonged time left entire.
Risk of sexually driven behaviours.
Risk of accidental mating's.
Special Considerations for Assistance Dogs
Our policy is that all working male dogs must be neutered or have a hormonal implant by 2½ years of age unless the dog is not considered to be developmentally mature by a veterinarian at that age.
This is to ensure:
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Hormonal and skeletal maturity is achieved
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Sexually driven behaviours are less likely to interfere with learning and work
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Unwanted pregnancies and training disruptions are avoided
⚖️ Final Thoughts
Deciding when to neuter is a complex topic that must account for your dog’s:
❗ Our Position
We believe in informed, evidence-based choice. However, we are not veterinarians, and we do not offer personalised advice on when or whether to neuter.
We strongly encourage you to:
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Review current veterinary research
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Consider your dog’s needs and long-term wellbeing
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Make a decision in consultation with your vet
➡️ Please note: this is not a subject we will advise on directly.
