Neutering and Spaying Dogs

Deciding whether and when to neuter a dog is no longer considered a one-size-fits-all decision. The dog’s sex, breed, size, age, health, behaviour, lifestyle and risk of an accidental mating should all be discussed with a veterinary surgeon.

Current UK Guidance

Updated guidance published by the British Veterinary Association and British Small Animal Veterinary Association in March 2026 recommends a contextualised, case-by-case approach.

Their general consensus is that, when neutering is appropriate, many dogs should be neutered at around 12 to 24 months, when they are closer to skeletal maturity. The correct age still varies according to breed and individual circumstances.

Spaying is generally recommended for female dogs that are not intended for breeding, commonly between 12 and 23 months.

Castration of male dogs should be considered individually and not carried out before physical maturity unless there is a compelling reason.

Possible Benefits

  • Prevents unwanted litters
  • Prevents testicular cancer in males
  • Prevents pyometra and ovarian disease in females
  • Prevents pregnancy and the risks of whelping
  • May reduce some hormone-related prostate conditions
  • May reduce roaming or sexually motivated behaviour
  • Can simplify the management of mixed-sex households

Possible Risks

  • Risks associated with anaesthesia and surgery
  • An increased tendency to gain weight
  • Urinary incontinence in some females
  • Coat changes in some breeds
  • Possible effects on fearfulness or behaviour
  • Increased risk of certain joint disorders when performed early in some breeds
  • Associations with particular cancers in some breeds and sexes

Growth and Joint Development

Sex hormones contribute to skeletal development and the closure of growth plates. Large and slow-maturing breeds may remain physically immature considerably longer than small breeds.

Research has found associations between neutering before skeletal maturity and an increased risk of joint disorders—including cranial cruciate ligament injury, hip dysplasia and elbow dysplasia—in some breeds.

The effect is not the same for every breed, sex or body size. These studies identify associations and cannot prove that neutering alone caused every condition.

Genetics, body weight, exercise, conformation and other factors are also important.

Cancer Risk

Neutering prevents cancers of the removed reproductive organs, but studies have also reported associations between neutering and higher rates of particular cancers in certain breeds.

The pattern varies greatly by breed, sex and age at neutering. A result from one breed should not automatically be applied to every other dog.

Spaying may reduce the risk of mammary tumours, but estimates of the size of this benefit vary and must be balanced against other health and welfare considerations.

Female Dogs

Leaving a female entire retains the risk of pyometra, an infection of the uterus that can become life-threatening and require emergency surgery.

Entire females also require careful management during every season to prevent mating.

Spaying prevents pyometra, ovarian disease and pregnancy. However, the timing should take account of physical maturity, season history, breed, body size, urinary continence and individual health.

Male Dogs

Castration prevents testicular disease and may help with some testosterone-driven behaviours or medical conditions.

It is not a guaranteed treatment for aggression, anxiety, poor training or excitement.

In a nervous or fearful dog, altering hormone levels may sometimes make behaviour worse. A qualified veterinary behaviourist should be involved when behaviour is the main reason being considered.

A temporary hormonal implant may sometimes help assess the likely effect before permanent surgical castration, although it does not reproduce every effect perfectly.

Alternatives to Traditional Neutering

Alternatives may include temporary medical suppression of fertility in a male, vasectomy, or hormone-sparing surgery. These procedures have different advantages, limitations and availability.

A vasectomy prevents a male from fathering puppies but does not remove testosterone-driven behaviour or prevent testicular disease.

Hormone-sparing surgery in a female may prevent pregnancy while retaining some hormone-related risks. Discuss the precise procedure and its consequences with the operating vet.

Questions to Discuss With Your Vet

  • Has my dog reached physical and skeletal maturity?
  • Are there breed-specific health risks to consider?
  • Is there a medical or behavioural reason to neuter now?
  • Can accidental mating be reliably prevented?
  • What procedure is proposed and which organs will be removed?
  • Would delaying the procedure alter the risks?
  • Are medical or hormone-sparing alternatives appropriate?
  • How should diet and exercise be adjusted afterwards?

Further information
BVA and BSAVA: Updated Neutering Guidance
Breed-Specific Neutering Research