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.


Pets as Gifts – Evidence not Anecdotes

ResearchBlogging.orgPets aren’t gifts. We all know that.

If a pet is given as a gift, the recipient might not be prepared for the financial commitment. The pet might be unsuitable to their lifestyle, or the recipieint may be uncommitted. And this means the pet is more likely to be relinquished.

But are you willing to be wrong about that?

This pretty shar pei has found her home through Adelaide All Breed Dog Rescue Inc.

This pretty shar pei has found her home through Adelaide All Breed Dog Rescue Inc.

“Studies of dog and cat relinquishment to shelters, however, show that the relinquishment of dogs and cats received as gifts is lower than from other sources,” says Weiss et al. in their 2013 paper. While this blog post will concentrate on this article, it’s important to note that this study builds on the research of others. For example (as summarised by Weiss et al.),

  • This article looked at 2600 dogs and 2300 cats, and found “Relinquished dogs infrequently came from pet shops, as gifts and from veterinarians. The study found the odds of dog relinquishment were higher when acquiring an animal from a shelter, friend, as a stray, and from a pet shop compared to receiving an animal as a gift”. Cats had similar trends.
  • This article “identified 71 reasons for pet relinquishment” and unwanted gift made up only 0.3% of dog surrenders and 0.4% of cat surrenders.
  • And this one found that being received as a gift was a protective factor, with dogs and cats received as gifts being “at [a] significantly decreased risk of being relinquished”.

Simply, there is no evidence that pets being given as gifts leads to relinquishment. It is an unfounded myth.

This study even says, “the myth that dogs and cats should not be given as gifts still persists“.


How was this study conducted?

A large telephone survey of 1006 adults was conducted, with 222 people saying they received a dog or cat as a pet in the last 10 years.

If an individual identified them self as a pet-gift-receipient, they were asked further questions. Were they involved in selecting the pet? How attached are they to their pet? Do they still own the pet?


And what did they find?

Some of the gifted-pets were rehomed – 21 out of the 215 pets. That is, 9.7%.

It didn’t seem to matter if the gift was a surprise or not – it wasn’t associated with people rehoming their pet, or being more or less attached to it.

“These results suggest that there is no increased risk of relinquishment for dogs and cats received as a gift.”

On a side note, this study is different, because it looked at owner retention, instead of shelter relinquishment data. This means that the statistic of 9.7% rehomed is probably higher than shelter surrender intake (as many pets would be rehomed privately instead of through shelter facilities).


How does this relate to shelters?

Weiss et al. express their concern about shelters who prohibit adoptions when they know that the animal is going to be given as a gift.  Weiss et al. says, not allowing pets to go as gifts may “impede the overarching goal of increasing adoptions of pets from our nations’ shelter system”.

Significantly, they say (emphasis my own):

“These findings may help animal welfare organisations open options for those interested in obtaining dogs and cats for their family and friends. It is important to note that animals obtained from a shelter are more at risk than those obtained as gifts. Allowing adoptions of dogs and cats to those obtaining the pet as a gift may decrease the risk of return or relinquishment for that dog or cat. Furthermore, it would allow for more animals from shelters to find homes.”


The next thing

Briefly, the article suggests that the next area for study is research and planning, and how that relates to pet retention. Current evidence suggests that ‘spur of the moment’ type acquisitions made with little or no research or planning are not associated with higher rates of relinquishment.


So have you ever received a pet as a gift? And did you keep that pet for its life?


Weiss, E, Dolan, ED, Garrison, L, Hong, J & Slater, M (2013). Should dogs and cats be given as gifts? Animals, 3 (4) DOI: 10.3390/ani3040995