When should I desex?

Desexing, also known as sterilisation or in the US spey & neuter, seems to be another galvanising topic in the dog world… As a training and behaviour professional, I do get asked my opinion a lot. I’m a big proponent of informed choice, so here are my thoughts and considerations on the subject. (Note I am not a vet).

As I am able to, I will add links to articles or studies that inform these considerations further. I envisage this may become a living blog, where as more information comes to light, my considerations may change.

Informed choice means there is no short answer, but in general for dogs I suggest between 6 & 18 months of age. The later the better, and not at all in some cases is OK too. It is ultimately an individual decision, based on your dog & circumstances.

For cats, the considerations are basically the same, but with their shorter reproductive cycles and community challenges I tend to support paediatric surgery by a well-practised vet.

If your puppy or dog came desexed early don’t worry – most dogs desexed at around 6 months of age (or before) do just fine! This article is for those that have the luxury of choice.

Effects on the body

The most reasonable argument to wait until around 12-18 months allows for your dog to reach skeletal & sexual maturity. This is less of an issue for smaller dogs (growth impact). Dogs desexed before maturity can retain their puppy looks and not “fill out” properly; the endocrine system should make up for any hormonal imbalance, which arguably puts more stress on that system.

Not desexing has increased risk of reproductive cancers & in females pyometra (infected uterus). Anecdotally, the occurrence of these is about the same percent as other non reproductive cancers, or issues associated with the increased strain on the endocrine system. Pyometra risk is also higher in females that don’t have a litter – though not every female needs to have a litter either!

Females have other considerations of their own too: Waiting until 12-18 months of age means you are likely to experience (and have to manage) at least 1 heat cycle, and desexing early seems highly correlated with incontinence issues that don’t always manifest until later, after the operation. If you are willing & able to manage the heat cycles, 3-4 years old seems a good age for females, based on these potential medical impacts.

A comprehensive article on surgical impacts is here: https://fall2018.iaabcjournal.org/2018/10/31/spay-and-neuter-surgery-effects-on-dogs/

Effects on behaviour

Taking away hormones does impact behaviour of course, though it should not be too significant. Testosterone can amplify behavioural predispositions so taking it away can appear to settle male dogs and remove any sexual frustration-type behaviours.

In some females the presence of testosterone without the female hormones in balance, seems to influence an increase in aggressive behaviours.

Legal Considerations

This section updated 1 August 2024

The other factor to consider is Lifetime registration in NSW. As of 1st July 2024, all pets must be registered by 12-weeks of age or immediately upon transfer (whichever happens first). This means that if you obtain your pet after 12-weeks of age, they should already be lifetime registered with the NSW Pet Registry (always check status when claiming your pet on the NSW Pet Registry). The additional fee for an un-desexed pet is applicable from 6-months of age. If you do not supply evidence that your pet is desexed by this age, your local Council, as the enforcers of the registration laws, should send a reminder to pay this, and if not paid on time may attract a late fee and even fines.

Your vet can apply for temporary or permanent exemption. A temporary exemption means you are able to delay the desexing age to whatever is agreed with your vet without paying the additional registration, assuming the application is accepted. This means when the agreed age approaches, the Council will send the reminder to pay if they have not been given evidence you have desexed your pet. A permanent exemption is rare and usually only for animals that have major medical issues, for example where anaesthesia is a risk to life.

The onus is on you to desex and provide evidence to the Council so they know not to charge the additional fee. If you are a bit late, or even if you did desex by the required age (6-months or vet agreed temporary exemption) but were late with the evidence, Council may still charge you the additional fee.

More info from the Office of Local Government: https://www.petregistry.olg.nsw.gov.au/owners/register-a-pet

What does your breeder/rescue say?

If you sourced your puppy from a rescue organisation or pound, or a registered ethical breeder, there may be a desexing or breeding clause in the contract of sale. Some specify an age to desex, wanting earlier desexing to avoid unintentional breeding, while some breeders may have a breeding clause and don’t want you to desex at all. The key here is to communicate – be open with the breeder or rescue, and work with them and your vet if/as needed.

Side note on breeding:

I honestly don’t know much about breeding, other than to do ethically it is hard work!

I’d absolutely go back to your breeder as first port of call. If they want to breed from a puppy they adopt to you, they will often include that in the contract. Clients with experience with this have told me how stressful it can be, to have your dog leave for mating, pregnancy, whelping, or a combination of those. But your breeder is in the best position to know their lines, best pairings, and all that.

I always discourage going it alone. It is hard work! And definitely not an easy way to make money. It is also not a health requirement for any/every dog to mate, or experience motherhood. Some aren’t good mums just like us (and that’s even harder on the humans to step up).