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Dogs Biting Dogs: Who and Where

Whether a dog bites another dog depends upon its size, sex, and neuter status.

Key points

  • Without considering a dog's breed, factors such as a dog's size, age, and sex are associated with the likelihood that it will bite other dogs.
  • The sex of a dog predicts the seriousness of the dog bite and which part of the victim's body is targeted.
  • Whether a dog is spayed or neutered is related to the probability that it will aggressively bite another dog.
Steve Baker/Flickr
Source: Steve Baker/Flickr

Most research on canine aggression has focused on the circumstances and situations in which dogs attack people. The reasons are obvious since we are generally most concerned about the safety of humans in our society. However, dogs are sometimes aggressive toward other dogs, and dog-to-dog attacks can have serious, even fatal, consequences for the dog that has been targeted.

Those few studies which have looked at dogs biting other dogs have mostly concentrated on physiological and genetic factors, although some others have focused exclusively on breed and training because they were concerned with those animals involved in illegal dog-fighting activities. However, a new study from the Czech Republic gives us a snapshot of the characteristics of family dogs that bite other dogs, not just in encounters outside but also in their home.

The New Study

This newest research on canine aggression comes from a team of investigators headed by Lenka Pillerova from Mendel University in Brno, Czech Republic. In some respects, it follows the pattern of research on human criminals, where information is gathered on known offenders, specifying the characteristics of the individual, the nature of the crime, and the impact of the crime, without delving into the motivational factors or the triggering circumstances. In other words, attempting to answer the questions of who, what, and where, but not why.

The new data was collected in three veterinary clinics in South Moravia. The study population consisted of 347 dogs known to have bitten other dogs. The owners of these biting dogs were interviewed directly by the research team members. The information gathered included basic demographics such as the biting dog's age, sex, neuter status, and also the location of the bites on the victim dog (head, neck, trunk, or limbs).

The statistical analyses were quite complex, involving logistic modeling; however, the main results are easily described, and there were some interesting findings.

Size and Sex

Considering biting incidents outside of their own household, nearly three-quarters of biting dogs were males, confirming other studies which suggest that male dogs are more likely to be involved in aggressive incidents. It was also the case that victim dogs were more likely to require medical treatment when bitten by male dogs rather than females.

As might be expected, most of the dogs doing the biting were adults, with puppies and senior dogs representing only a small percentage of the biters. A dog's size was a major factor. Large dogs accounted for the highest percentage of biters (57 percent) and small dogs for the smallest percentage (15 percent) of aggressors.

The Effect of Neutering

In this study, whether the dog was neutered seems to play a major role. In the population of biting dogs, only 4 percent of the females had been spayed. Even more dramatically, only one-half of 1 percent of the male dogs that bit other dogs were neutered.

For bites occurring outside of their own household, the most common target was the neck of their victim (42 percent), followed by the trunk (35 percent). The target of bites, however, depends upon the size and sex of the biting dog. Bigger dogs are more likely to bite the head, and females, regardless of size, are also more likely to target the head of their victim.

A Practical Finding

Perhaps the most significant finding, in terms of practical implications, had to do with the frequency of biting by dogs that were on leash versus those who were unleashed. Wearing a leash seems to significantly reduce the likelihood of dog-to-dog aggression. This study found that 79 percent of the dogs engaged in biting incidents outside of their own household were unleashed.

Some psychologists have speculated that the dog views the leash as an extension of its owner's hand. This seems to be confirmed by the fact that dogs are more likely to be obedient and under control when they are on a leash, even if no force or pressure is currently being exerted by the leash. Based upon these new data, it would seem that if there are any concerns that your dog might be aggressive toward other dogs, the best preventative might be the simple act of clipping your leash onto its collar before taking them outside for a walk.

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission.


Lenka Pillerova , Eva Koru , Kristyna Holcova , Zdenek Havlicek, Petr Rezac. (2022). Dog-to-dog bites inside and outside the biting dog’s household, Journal of Veterinary Behavior, doi:

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