De-sexing Cats & Dogs: A Clearer Look at a Routine Decision

For many, this is a routine procedure that starts with a cautious drop off and ends with a sleepy pet at home. Most of the time, it’s just part of being a responsible pet owner. Because the concept is so familiar, desexing for cats and dogs is rarely discussed in much detail. Still, it is definitely worth understanding better if you have furry companions at home. Being faced with this decision can start valuable conversations about animal health, behaviour and individual needs. And it can prompt a closer look at how many of the common myths around these topics are actually true!

At Edgeworth Animal Medical Centre, we’re a local, independent clinic caring for pets throughout all stages of their lives. That includes routine de-sexing, which can be a sensitive topic and one we always take the time to talk through properly.

There are plenty of assumptions around de-sexing. In reality, most councils across Australia require cats and dogs to be de-sexed unless an exemption applies, such as registered breeders, working dogs or certain medical reasons. In NSW, this is commonly set at around four months for cats and six months of age for dogs, unless a delay or exemption is recorded on the NSW Pet Registry. This is the standard approach supported by veterinary bodies and followed by most practices, including our team.

Within that framework, there is still room for clinical judgement. At Edgeworth Animal Medical Centre, where appropriate, we prefer to allow animals to grow closer to adult size before surgery, particularly where overall development is still underway. This is handled as a planned delay and formally recorded on the patient’s file with the NSW Pet Registry.

Breed-specific studies around de-sexing are often raised by owners and frequently shared online. While this research is considered, many of these studies involve relatively small numbers of dogs and are not treated as definitive on their own. Instead of applying broad conclusions, we weigh this information carefully alongside clinical experience and the individual pet. In most cases, that still leads us to recommend routine de-sexing.

The short answer is yes. The bigger question is whether they are the right fit for most pets.

One alternative we offer for male dogs is vasectomy. This allows owners to meet permanent sterilisation guidelines without removing male sex hormones. However, hormone-driven behaviours like marking and roaming remain. For some owners, that may be the goal. For many others, these behaviours are exactly what they hope to reduce, which is why routine castration remains more common.

Some clients ask about ovary-sparing spey procedures, but we don’t offer them. There’s a real concern that this approach can put pets at unnecessary risk, including traumatic mating and a higher chance of mammary cancer later in life.

For female dogs, staying entire isn’t just about managing seasons. Each heat lasts around two weeks and requires close supervision to prevent mating. For most owners, keeping up with this multiple times over a dog’s life quickly becomes impractical.

There are other important health risks to keep in mind. Undesexed female dogs have a significantly higher risk of mammary cancer, and womb infections are relatively common and sometimes life-threatening in older dogs.

Unlike humans, canines do not go through menopause, which means they can still become pregnant later in life, even when their bodies are no longer suited to carrying or delivering a litter. I have treated older dogs in this situation, including a beautiful 13-year-old Border Collie who underwent a higher-risk spey. While she sailed through surgery and recovery, the outcome could very well have been different.

And then there are risks associated with spey surgery itself, regardless of age. A small percentage of female dogs develop urinary sphincter mechanism incompetence after surgery. While this condition is uncommon, it is not rare. It is easily managed with medication, although treatment is often ongoing.

As mentioned earlier, spey surgery is major abdominal surgery, and that is important for owners to understand. It is also performed today with a high margin of safety, using modern anaesthesia, monitoring and surgical standards. Significant complications are now extremely rare.

When it comes to behaviour, there’s a lot of misunderstanding about what de-sexing will change. Some of it is partly true, but much is not. It’s important to know what this procedure can influence… and what it won’t.

You may have heard that de-sexing will make your pet overweight or lazy. In reality:

• Castration will usually reduce a male dog’s drive to seek out females, which was historically a major cause of roaming and subsequent ‘hit by car’ accidents.
• On the whole, your dog’s personality will remain much the same. De-sexing does not turn energetic dogs into couch potatoes. If they are naturally bouncy, they usually stay that way.
• There is a normal metabolic slowdown that happens around the time of de-sexing in many breeds, which is why weight gain is sometimes blamed on the surgery itself.
• Routine castration has been shown to resolve around 70 per cent of certain house soiling behaviours, particularly urinating inside the home.
• Fearful or aggressive behaviour is unlikely to resolve simply because a pet has been de-sexed. In most cases, these behaviours continue on their current course and require targeted support such as training or, in some cases, medication.

Routine does not mean rushed, and every pet deserves considered care.

At Edgeworth Animal Medical Centre, we believe de-sexing should always be an individualised discussion. All vets at our practice perform these surgeries because we know they result in better long-term health outcomes for the majority. If you’d like to know more about our de-sexing services, contact our friendly team today.

By Dr Perin Patterson