Desexed dogs – 2.6 times less likely to bite!

Australian Veterinary Association makes this claim, in its PDF “Dangerous Dogs – a sensible solution“:

Entire (undesexed) dogs are 2.6 times more likely to bite than those that are spayed or neutered (desexed)

Are undesexed dogs really that risky?

I decided to read the three studies referenced individually.





Messam, LL, Kass, PH, Chomel, BB, Hart, LA 2008, ‘The human-canine environment: a risk factor for non-play bites?’, Veterinary Journal, 177(2); 205-15.

This study used data from 2003 (11 years ago) collected in Kingston, Jamaica and San Fransico, USA. Participants were recruited from vet clinic waiting rooms where they were presented with a questionnaire, set to determine the nature of their dog’s biting behaviour (and differentiating it from play biting).

When it came to comparing entire and gonadectomised dogs, this research suggests:

  • Intact dogs are more likely to bite than desexed dogs
  • Intact males are 1.68 times more likely to bite than desexed males
  • Intact males were 0.8 times more likely to bite than intact females
  • Spayed females were the ‘least bitey’


Guy, NC, Luescher, UA, Dohoo, Se, Spangler, E, Miller, JB, Dohoo, IR and Bate, LA 2001, ‘Demographic and aggressive characteristics of dogs in general veterinary caseload’, Applied Animal Behaviour Science, vol 74, iss 1. 

This research is based on data collected in Cannada in 1996 (18 years ago), targeting owners with a questionnaire waiting for vet appointments in three Canadian provinces. Their results indicate:

  • The lowest level of aggression (biting and growling) was reported in intact female dogs
  • Intact male dogs were twice as likely to have bitten as intact female dogs
  • Intact male dogs and neutered females incidents of biting was reported at a similar level

And to quote:

“Relative to intact female dogs, neutered male dogs of at least 1 year of age were at the highest risk for having previously shown biting behaviour, followed by neutered female dogs, and intact males… [O]ur results indicate that the behavioural outcomes of [neutering] are worthy of further investigation.”


Gershman, KA, Sacks, JJ & Wright, JC 1994, ‘Which dogs bite? A case-control study of risk factors’, Pediatrics, 93 (6 pt 1), 913-7. 

This study used data from 1991 (23 years ago) using 178 dog bites requiring medical treatment of a non-household-member in Denver, USA. Data was only used for dogs that had not bitten before. The study itself recognises this is a small sample size.

Their data concludes:

  • not-neutered dogs were 2.6 times more likely to bite
  • chained dogs were 2.8 times more likely to bite
  • dogs living with a baby were 3.5 times more likely to bite
  • male dogs were 6.2 times more likely to bite


So, are entire dogs 2.6 times more likely to bite?

If you are looking at the study in Denver, USA, in 1991 (23 years ago!) then, yes, their conclusions indicate that intact dogs are 2.6 times more likely to bite than desexed dogs.

But the other evidence referenced by the AVA does not make the exact same conclusions. The study conducted in 2003, using data from Jamaica and the USA, found that intact males were 1.68 times more likely to bite than castrated males, and 0.8 times as likely to bite as intact females. (This study is also old, with the data being collected 11 years ago.)

And that other article, with data from Canada in 1996 (18 years ago) makes pretty much the opposite conclusion. They found that neutered male dogs were the riskiest in terms of bites.


Questions to ask…

Why are we relying on data over a decade (or two decades) old? If aggression in entire dogs was a common phenomenon, surely we would have countless studies showing this problem.

Where is the Australian data-set?

Where is the study that controls for factors such as selectionsocialisation, and socio-economic factors?


What the AVA should really be saying is:

According to one study conducted in Denver, USA, 23 years ago, entire dogs were found to be 2.6 times more likely to deliver a bite (that required medical treatment) to a stranger than desexed dogs.


Are they good with kids?

The common question: Are they good with kids?

What it is really asking is: Does this particular breed bite?

And the answer is: Yes. This breed, and every other breed, bites.


Puppies in a pen with a child peering in.Dog bites are a lot more complex than simple ‘breed’.  Families with children and dogs need to recognise that any child-dog interaction can end up in a bite, regardless of breed.  However, there are a number of ways that dog bite risk can be minimised.

It is very possible for dogs and children to live safely together, but it involves setting the dog and the child up for success, and managing interactions to ensure they are positive.


The Dog

Dogs need to be selected with care as they form an important part of the picture.  For a dog to be ‘good with children’,  they need to be adequately socialised, trained, and have a stable genetic personality and temperament.  Your role, if you’re looking to add a dog to your family, is to select a breeder using stable dogs with good temperaments who socialise their dogs and puppies to all people, including young children.  Once you’ve added one of these well-bred, well-socialised puppies to your family, the next step is to continue to socialise the puppy well with all people, train the puppy appropriate behaviours (e.g. not to jump up), and police child interactions with the dog.

That is, a dog needs to be selected, socialised and trained to be the best dog they can be, and then well managed – for life.


The Child

Children need to be taught to interact appropriately with dogs.  Dogs with stable temperaments should not then be an invitation for children to climb on, poke, or otherwise tease or irritate the dog.  Even good dogs have limits.  Children should be taught to:

  • Always leave dogs alone that are sleeping.
  • Always leave dogs alone that are eating.
  • Always leave the dog alone when they go to their special place (which could be the dog’s crate, bed, or kennel).
  • Always leave dogs along that are acting fearful (and how to identify a dog that is scared).
  • Always leave dogs along that are acting aggressive (and how to identify a dog that is angry).
  • To pat dogs on the chin and chest, and avoid hugging or squeezing a dog.
  • Never do anything that could hurt the dog.
  • Never grab a dog by its collar.

All these interactions are high risk for children, as dogs don’t like being interacted with in these ways, and it may lead to them biting.  Children need to have rules concerning their interactions with all dogs, for their own safety.



As the dog’s owner and child’s parent, you play an important role in managing the interactions that take place between the dog and the child, and ensuring they are appropriate and safe.  For example, it is your job to ensure that children know not to approach a dog that is eating, while also ensuring that the dog is always removed from the children while eating.  If you think your dog may be fearful during a child’s birthday party, perhaps putting the dog in boarding kennels for the weekend or otherwise confining the dog would be an option.  Management also includes alert, conscious supervision of all dog-child interactions: The mantra of “Supervise or Separate”.  If you can’t watch how dog and child are interacting, then separate the dog from the child.

If you know there are deficiencies in your dog’s temperament or your child’s behaviour, then your management attempts should be set up to prevent these deficiencies giving rise to a dog bite.

 A young border terrier sleeping with a child reading the puppy a story.


Any breed that is described as ‘good with kids’ is, at the very least, being deceptively advertised.  Dogs are living individuals, and there’s no guarantee how they will behave with children.

As you can see, the question “Are these dogs good with kids?” is a complex question.  Any dog can be good with kids, provided they are come with a genetic ‘good temperament’ and are well socialised, and well trained.  However, this dog can only be expected to be ‘good’ if the kids interact in respectful and safe ways with the dogs, and all interactions are constantly monitored to ensure all parties are safe.

Having a safe home environment for children is a lot more than just choosing the right breed – it’s an ongoing commitment to education and management of both dogs and children.

If you want your dog to be good with the kids, you really should be asking, “Am I good at management?”


Further reading: See Resources for New Puppy Owners, particularly the links under ‘Children and Dogs’.