When Should I Desex My Dog or Cat?

Desexing - also called spaying (females) or castrating (males) - is one of the most common and important procedures in veterinary practice. It prevents unwanted litters, reduces the risk of several serious health conditions, and in most cases makes for a calmer, healthier companion. The most common question owners ask is: when should I do it?

The answer has changed over the past decade as research has refined the recommendations, particularly for dogs. Here is the current guidance we use at Eltham Veterinary Practice.

Desexing dogs: timing by size

The traditional advice was to desex dogs at six months of age. This recommendation is being updated for many breeds as research shows that the timing of desexing can affect long-term health outcomes, particularly for larger breeds.

Small and medium breeds (under 20kg adult weight) - desexing from 5 to 6 months of age is generally appropriate. The health and behavioural benefits of early desexing are well established for these breeds and the hormonal influence on bone development is less significant.

Large breeds (20 to 40kg adult weight) - consider waiting until 12 to 18 months for females and 12 months for males. Research in Labrador Retrievers, Golden Retrievers, and similar breeds shows that allowing growth plates to close before desexing reduces the risk of certain orthopaedic conditions and some cancers.

Giant breeds (over 40kg adult weight) - waiting until 18 to 24 months is often recommended. Discuss this with your vet as the right timing depends on the individual dog's development and lifestyle.

These are general guidelines. The right timing for your dog depends on their breed, sex, home environment (particularly whether intact dogs of the opposite sex are present), and any specific health considerations. Our vets will give you a personalised recommendation at your puppy consultation.

Desexing cats: timing

Cats are different to dogs in this regard. The case for early desexing of cats is clearer, and the concerns about hormonal influence on development are less significant.

• Desexing from 4 to 6 months of age is recommended, before the first heat cycle in females
• Male cats should be desexed before 6 months to prevent spraying behaviour and roaming from becoming established
• Earlier desexing (from 8 weeks, sometimes called paediatric desexing) is performed by some vets and is safe when done correctly

Desexing a female cat before her first heat virtually eliminates the risk of mammary tumours later in life - the risk increases significantly with each heat cycle. This is one of the strongest arguments for not delaying in cats.

What does the procedure involve?

Desexing is performed under general anaesthesia. At Eltham Veterinary Practice, every patient receives a pre-anaesthetic examination and, for older animals, pre-anaesthetic blood tests to ensure they are safe to proceed.

For females (spaying), the ovaries and uterus are removed through a small incision in the abdomen. For males (castration), the testicles are removed through a small scrotal or pre-scrotal incision. Most patients go home the same day and recover well within a week. You will need to keep your pet confined and calm for 10 to 14 days, check the incision daily for swelling or discharge, prevent licking of the wound using the cone provided, and return for a post-operative check at 10 to 14 days.

Health benefits of desexing

Female dogs and cats: eliminates the risk of pyometra (a life-threatening uterine infection), significantly reduces mammary tumour risk when done early, and removes the risk of ovarian and uterine cancer.

Male dogs and cats: eliminates testicular cancer, reduces the risk of prostate disease, and reduces roaming and territorial behaviours that lead to injuries and road trauma.

Desexing and weight gain

Desexed animals have a lower metabolic rate and can be prone to weight gain if fed the same amount as before the procedure. This is easily managed by adjusting portion size and choosing an appropriate adult food. Our team can advise on diet adjustments at the time of desexing or at your post-operative check.

How much does desexing cost?

The cost varies depending on species, size, sex, and whether additional procedures or blood tests are required. Call us on (03) 9439 8650 for a quote, or ask at your next appointment. Pet insurance often covers desexing under some policies - check your policy details or read our guide on pet insurance in Australia.

To discuss the right timing for your pet's desexing, book an appointment online or call us on (03) 9439 8650. We are open Monday to Friday 8am to 7pm and Saturday 9am to 1pm.