Neutering — spaying females and castrating males — is one of the most common operations in veterinary practice. For decades the advice was simple: neuter every pet, early. For cats, that advice has largely stood the test of time. For dogs, the research of the last fifteen years has made the picture more nuanced, and many vets now tailor the timing to the individual dog.
Cats: neuter early
Most vets recommend neutering cats at around four months, before they can breed. Female cats can become pregnant from four months old, and unneutered cats roam, fight, spray and are at higher risk of injuries and infections such as feline immunodeficiency virus. Early neutering is safe for cats and prevents a great deal of suffering.
Dogs: the benefits
- Prevents unwanted litters.
- Spaying prevents pyometra, a life-threatening womb infection that affects a large proportion of unspayed older bitches, and greatly reduces the risk of mammary tumours if done early.
- Castration prevents testicular cancer and reduces prostate problems.
- Can reduce roaming and some hormone-driven behaviours, such as marking and mounting.
Dogs: the trade-offs
Studies, particularly in some large breeds such as Golden Retrievers, Labradors and German Shepherds, have linked neutering before maturity with higher rates of certain joint disorders, such as cruciate ligament rupture and hip dysplasia, and some cancers. The effects vary by breed and sex, and not all studies agree. Neutered dogs also need fewer calories and can gain weight, and some spayed bitches develop urinary incontinence later in life.
What this means for timing
- For small breeds, the balance of evidence generally still favours neutering at around six months.
- For large and giant breeds, many vets now suggest waiting until the dog is fully grown — often twelve to eighteen months or later.
- For female dogs, your vet will weigh the benefits against the timing of seasons.
There is no single right answer for every dog. Talk to your vet about your dog’s breed, size, sex, lifestyle and health — and whether you can safely manage an entire dog or bitch in season in the meantime.
Behaviour isn’t always improved
Castration doesn’t fix every behaviour problem. It may reduce behaviours driven by testosterone, but fear-based problems can sometimes get worse. Discuss behaviour concerns with your vet or a qualified behaviourist before deciding.
Recovery
Most pets go home the same day. Expect about ten days of rest and lead walks, a cone or body suit to stop licking the wound, and a check-up. Call your vet if the wound is swollen, weeping or opening, or your pet is off food.
Questions owners ask
Should a female dog have one season before spaying?
Not necessarily. Spaying before the first season gives the greatest protection against mammary tumours, but for large breeds some vets prefer to wait. Your vet can advise.
Will neutering change my pet’s personality?
Your pet’s core personality stays the same. Some hormone-driven behaviours may decrease.
Are there alternatives to surgical castration?
In some countries, a hormone implant can temporarily and reversibly suppress fertility in male dogs. It can be a way to see how a dog behaves without testosterone before deciding.
Written by
Maya edits every page before it goes to review and keeps the reference library up to date. (Demo profile supplied with the Tailwise theme — replace it with your own team.)
Reviewed by
Tailwise is for general information and is reviewed by veterinary professionals, but it is not a substitute for advice from your own vet, who knows your pet. How we check facts
