What every pet owner should know

Sterilisation, also known as neutering, is one of the most common and beneficial procedures performed in veterinary medicine. It involves surgically preventing animals from reproducing and offers important health, behavioural, and welfare benefits for both pets and the wider community.

This article explains what the procedure involves, why it is recommended, the timing options, and how to care for your pet at home after surgery.

What does sterilisation involve?

Female dogs and cats (Spaying)

Spaying is a surgical procedure performed under general anaesthesia. It usually involves the removal of both ovaries and the uterus as well (ovariohysterectomy). The surgery is performed through a small incision in the abdomen. Removing the ovaries stops heat cycles, prevents pregnancy, and eliminates the hormonal influences that can lead to certain serious diseases.

Male dogs and cats (Castration)

Castration involves the removal of both testicles under general anaesthesia. The incision is small and located just in front of the scrotum (dogs) or directly over the scrotum (cats). This procedure prevents sperm production and significantly reduces testosterone-driven behaviours.

Why is sterilisation recommended?

Sterilisation is recommended for most pets because the benefits generally far outweigh the risks.

Health benefits

Females

• Prevents life-threatening uterine infections (pyometra)
• Greatly reduces the risk of mammary (breast) cancer, especially if done before the first or second heat
• Eliminates the risk of ovarian and uterine cancers
• Prevents complications associated with pregnancy and birth

Males

• Prevents testicular cancer
• Reduces prostate disease
• Lowers risk of hormone-related tumours and perianal disease (especially in dogs)

Behavioural benefits

• Reduced roaming and escape behaviour
• Less hormone-driven aggression
• Decreased urine marking (especially in male cats)
• Reduced frustration and anxiety related to sexual behaviours

Population control

• Prevents unwanted litters
• Reduces the burden on shelters and rescue organisations
• Helps control stray and feral animal populations

Risks of sterilising vs not sterilising

Risks of sterilisation

• As with any surgery, there are small risks associated with anaesthesia and infection
• Possible weight gain if diet and exercise are not adjusted
• In some dogs, especially large breeds, timing of sterilisation may influence joint development

These risks are generally low and manageable when the procedure is performed by a veterinarian with appropriate monitoring and care.

Risks of not sterilising

• Unplanned pregnancies
• Pyometra (a life-threatening emergency) in females
• Higher risk of mammary cancer in unspayed females
• Testicular and prostate disease in males
• Increased roaming, fighting, injuries, and behavioural issues

Timing of sterilisation: early vs later

There is growing discussion about when to sterilise, particularly in dogs. The ideal timing can depend on species, breed, size, and individual lifestyle. There is no single “perfect” age for every dog, and decisions are increasingly made on a case-by-case basis.

Sterilisation around 6 months of age (traditional approach)

Pros

• Prevents accidental breeding before sexual maturity
• Maximally reduces the risk of mammary cancer in females
• Surgery is generally easier and therefore quicker and safer with faster recovery
• Well-established, predictable outcomes
• Particularly appropriate for cats and small-breed dogs

Cons

• In some medium-to-large and giant breed dogs, early sterilisation may slightly increase the risk of:
  • Certain joint or ligament problems (such as cruciate ligament disease)
  • Orthopaedic conditions related to altered growth patterns (such as hip dysplasia)
• Early removal of sex hormones leads to lifelong elevation of luteinising hormone (LH), which is thought to play a role in some hormone-associated conditions in a small number of dogs (see the next section for more detail)

Sterilisation later in life (after physical maturity)

Pros

• Allows full skeletal and muscular development, especially in large and giant breed dogs
• May reduce the risk of certain orthopaedic conditions in predisposed breeds

Cons

• Increased risk of accidental breeding
• Females will experience heat cycles and associated behavioural changes
• Lifetime risk of mammary cancer increases with each heat cycle
• Ongoing risk of pyometra until sterilised
• Hormone-driven behaviours may become established and harder to modify even with sterilisation

Important note:

Cats are almost always best sterilised early (around 6 months), as they reach sexual maturity quickly and contribute significantly to overpopulation.

Your veterinarian can help guide the most appropriate timing for your individual pet.

And while there is no single “perfect” age, there is a fairly clear modern consensus for large and giant breed dogs that balances the LH issue, orthopaedics, and reproductive disease risk, which is that sterilisation is increasingly recommended after skeletal maturity, typically:

• Females: ~ 12–18 months (after 1-2 heat cycles)
• Males: ~ 12–24 months

This timing aims to:

• Allow normal growth plate closure
• Reduce orthopaedic risk
• Delay the onset of lifelong LH elevation
• Still intervene before age-related reproductive disease becomes likely

Understanding hormones and long-term risk (simplified)

After sterilisation, the body produces higher levels of a hormone called luteinising hormone (LH) because the ovaries or testicles are no longer present to provide hormonal feedback. LH receptors exist in several body tissues, and ongoing research suggests this may contribute to a small increased risk of certain conditions or diseases in some dogs, particularly large breeds.

It is important to understand:

• These risks are not seen in every dog
• They are breed- and size-dependent
• The overall risk to an individual dog is usually low
• For many pets, the benefits of sterilisation still clearly outweigh the risks

For this reason, veterinarians increasingly recommend individualised timing, particularly for large and giant breed dogs.

Due to this LH surge syndrome, there is emerging interest in LH-sparing alternatives (e.g. vasectomy, ovary-sparing spay, chemical castration), though availability, long-term data, and owner compliance remain limiting factors. It is important to understand that although these options prevent your cat or dog from reproducing, they do not provide the health and behavioural benefits associated with traditional surgical sterilisation.

Aftercare at home: what to expect

The first 24–48 hours

• Your pet may be sleepy or quiet due to anaesthesia
• Appetite may be reduced initially
• Mild discomfort is normal and managed with prescribed pain medication

Wound care

• Check the incision daily for redness, swelling, discharge, or licking
• Do not allow licking or chewing — if this occurs an Elizabethan collar is essential
• Keep the incision clean and dry
• Do not bathe your pet until at least 10 days after surgery

Activity restriction

• Dogs may have leash walks only for 7–10 days
• No running, jumping, or rough play
• Cats should be kept indoors during recovery

When to contact your vet

• Excessive swelling, redness, or discharge
• Lethargy lasting more than 48 hours
• Vomiting, loss of appetite, or signs of pain
• If stitches open or the wound looks abnormal

In summary

Sterilisation is a safe, routine procedure that offers lifelong benefits for most dogs and cats. While the timing may vary depending on the individual pet, the overall advantages — including disease prevention, behavioural stability, and population control — make it one of the most important preventative healthcare decisions a pet owner can make.

If you have questions about whether sterilisation is right for your pet, or when the best time might be, your veterinarian is always the best source of personalised advice.