In this article

1. Start with the current guidance and the intended procedure
2. The benefits are different for females and males
3. Breed studies give clues, with limits
4. What the incontinence studies add
5. Age and puberty are not interchangeable research measures
6. Behaviour and alternatives need their own discussion
7. Leave with a plan for waiting and recovery

“When should we book the operation?” sounds like a question with one date as its answer. Current BVA and BSAVA guidance asks for a wider discussion: whether neutering is appropriate, which method to use and when, considering the dog's sex, breed, maturity, health and circumstances¹.

That leaves room for a useful conversation, even when friends have been given different advice for their dogs. Bring your questions before putting a date in the diary. The aim is to understand the recommendation for the animal in front of you and what you need to manage around it.

Start with the current guidance and the intended procedure

The BVA/BSAVA policy generally favours spaying female dogs. It recommends timing between 12 and 23 months according to breed and expected maturity, unless breeding is intended. For males, it recommends a case-by-case decision and, if castration is chosen, waiting for physical maturity unless there is a compelling contextual reason to act earlier¹.

Those are professional recommendations to discuss with your vet, not a birthday rule to apply yourself. The policy recognises that preventing pregnancy, household management and individual medical needs can change the balance. A separate conversation before booking helps establish what is proposed and why¹.

In the usual operations, castration removes the testicles and spaying removes the ovaries, sometimes with the womb. PDSA describes these as procedures requiring general anaesthesia and pain relief, with possible complications despite their routine use. Ask the team which operation they mean and how they assess your dog's surgical risk².

The benefits are different for females and males

PDSA lists prevention of pregnancy, seasons, false pregnancy and womb infection among benefits of spaying. For males, castration prevents testicular cancer and reduces benign prostate enlargement. The reasons for considering one dog's operation may therefore be quite different from the reasons for another's².

Pyometra is a serious womb infection in unspayed females. PDSA describes the usual timing as four to eight weeks after a season, although an unwell dog needs assessment regardless of the calendar. Signs include increased drinking, vomiting, reduced appetite, low energy, a swollen tummy, discharge or collapse. Closed-cervix infections may produce no visible discharge³.

That is part of the decision about timing: you need an arrangement for the period before surgery as well as for the operation itself. Ask the practice what to watch for and make sure every carer knows where the out-of-hours contact details are kept.

Breed studies give clues, with limits

A much-discussed 2020 study examined records for 35 breeds, including three Poodle sizes, at a University of California veterinary hospital. Associations between neutering age and certain joint disorders or cancers differed by breed and sometimes by sex. Most small breeds showed no detected increase in the joint disorders studied, while some larger breeds did⁴.

The authors could not tell why owners had chosen neutering or its timing. This was one hospital's records, including referral patients, and many dogs' last recorded visits were well before old age. It therefore cannot describe every breed's lifetime cancer risk or prove that an operation caused a later disease. Use breed-specific findings as material for the consultation⁴.

If someone shares a striking percentage from a breed table, ask what condition was counted, how many dogs were involved and whether the figures concern males or females. You can take the paper to the practice without arriving with a decision already made from one row.

What the incontinence studies add

A 2024 UK VetCompass study used records for 1,500 female dogs to emulate a trial comparing spaying at three to under seven months with seven to eighteen months. The later group had an estimated 20% lower odds of urinary incontinence diagnosed before eight-and-a-half years. This is a relative difference in odds, not twenty fewer affected dogs in every hundred⁵.

The researchers used methods designed to address confounding, but the underlying records were observational. Missing information and unmeasured differences could still alter the interpretation. First-season dates were often unavailable, so the study does not establish a universal before-versus-after-first-season rule. Nor did it compare every possible age or all health outcomes⁵.

A 2025 prospective UK study followed 306 female Labrador/Golden Retriever crosses in an assistance-dog programme, neutered before or after their first season. Cruciate ligament disease occurred in eleven of 155 dogs in the earlier group and one of 151 in the later group. Some other musculoskeletal outcomes also favoured the later group⁶.

Urinary incontinence was uncommon, with no statistically significant difference between those groups. That does not overturn the larger record-based study or prove identical risk. The programme's related breeds, management and small numbers for many diseases limit wider application. Some dogs also lacked complete lifetime follow-up⁶.

The useful question is which evidence is closest to your dog and the decision you face. A finding about one outcome cannot answer the entire question about surgery, pregnancy prevention, behaviour and future care.

Age and puberty are not interchangeable research measures

A 2024 scoping review retained 33 studies across five areas of female-dog health, but only six classified surgical neutering in relation to known puberty. Much of the literature instead used age bands. The reviewers found too little reliable evidence to settle the effects of neutering before or after puberty across those health outcomes⁷.

Its searches ended in May 2023, so that conclusion must be read alongside later work, including the 2025 prospective study. The review also identified inconsistent methods and potential bias, including in research about mammary tumours. Claims that one timing choice guarantees protection from cancer go beyond what this evidence can offer⁷.

It is reasonable to ask the vet to explain where their recommendation comes from: current guidance, evidence for your dog's breed and sex, a particular clinical concern or your household's circumstances. You should come away understanding the main reasons, without having to become an expert in every paper.

Behaviour and alternatives need their own discussion

BVA's owner-facing guidance says castration does not necessarily prevent aggression and may worsen fear-based aggression in some dogs. It recommends a behavioural assessment when behaviour is a key reason for neutering. Describe the problem specifically and ask your vet about a registered behaviourist, instead of booking surgery with the expectation that it will generally calm your dog⁸.

The same guidance discusses medical and surgical alternatives. A temporary implant is not a guaranteed preview of the behavioural effects of permanent castration; an initial hormonal flare can also affect behaviour. Ask about onset, ongoing commitments, possible unwanted effects and what happens when treatment ends. Fertility recovery should not be assumed to be identical for every dog⁸.

You can make the conversation clearer by naming the outcome you hope for. Is the immediate concern an unwanted mating, an existing medical problem or something happening on walks? Put each concern on the list so it can receive an appropriate plan.

Leave with a plan for waiting and recovery

PDSA advises keeping unneutered females apart from entire males during a season and contacting the practice promptly after accidental mating. After surgery, rest, wound protection and check-ups matter. Follow the team's individual instructions on preparation and recovery, including when to call about a concern; do not replace them with a generic timetable².

Write down the agreed next step, even if that step is a review appointment rather than an operation date. A clear plan makes room for the evidence and the practical reality of caring for your dog.

Sources and further reading8 sources

The small numbers in the article link to the source behind each fact. Sources open on their own websites.

1. BVA and BSAVA policy position on Neutering of Cats and DogsBritish Veterinary Association / BSAVA
2. Dog neutering – a guide to castration and spayingPDSA
3. Pyometra (infected womb) in dogsPDSA
4. Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary IncontinenceFrontiers in Veterinary Science
5. Later-age neutering causes lower risk of early-onset urinary incontinence than early neutering—a VetCompass target trial emulation studyPLOS ONE
6. A Prospective Study Investigating the Health Outcomes of Bitches Neutered Prepubertally or Post-PubertallyAnimals
7. Effect of neutering timing in relation to puberty on health in the female dog—a scoping reviewPLOS ONE
8. Neutering of cats and dogsBritish Veterinary Association