Canine Aggression: What Causes Dogs to Attack?

Dogs Playing
Image Courtesy of Jiggoja,

Dog attacks that lead to severe injuries or death are rare, but when they occur, they tend to receive a lot of media coverage, particularly when certain breeds are involved. This focus on dog breeds obscures the true causes of canine aggression.

Research into the characteristics of attacking dogs and their owners provides insights into how dog attacks could be prevented.

Top Causes of Dog Aggression

Summarizing the results of prior research, Clarke (2009) notes that common causes of dog aggression include:

    • predatory behaviour (six studies)
    • fearfulness (six studies)
    • inter-dog aggression (five studies)
    • dominance (five studies)
    • pain (five studies)
    • territoriality (four studies)
    • maternal protectiveness (four studies)
    • other protectiveness (three studies)
    • learned behaviour (three studies)
    • punishment (two studies)
    • redirected aggression (two studies)
    • irritability (one study)
    • possessiveness (one study)
    • instrumental goals (one study)
    • competitiveness (one study)
    • pathology (one study)
    • food-related (one study)

Patronek et al. (2013) conducted a longitudinal dog bite fatality study. Key findings included the following:

    • In 87.1% of cases, there was no able-bodied person available to intervene.
    • In 85.2% of cases, the victim had no relationship with the attacking dog(s).
    • In 84.4% of cases, the owner did not spay or neuter the dog(s).
    • In 77.4% of cases, the victim was not able to appropriately manage interactions with the dog(s) due to age or physical condition.
    • In 76.2% of cases, the dog had been isolated from people – a resident dog rather than a family dog that is loved and has opportunities to interact positively with people (resident dogs are often left chained up in yards or garages or left to roam alone outside).
    • In 37.5% of cases, the owner did not appropriately manage the dog(s).
    • In 21.1% of cases, the owner abused or neglected the dog(s).*
    • In 80.5% of cases, four or more of these factors contributed to the attack.

Other researchers have identified similar contributors to dog aggression. For example, research conducted by Gershman et al. (1994) found that biting dogs were typically unneutered males that were left chained up in yards.

Characteristics of Dog Owners That Contribute to Dog Aggression

Ragatz et al. (2009) conducted a study to examine the characteristics of dog owners that may contribute to canine aggression, and the findings provide insights into the reasons why particular breeds seem more likely to attack. The researchers found that owners of stigmatized breeds such as Pit Bulls, Akitas, Chow-Chows, Rottweilers, Dobermans, and wolf hybrids were more likely to engage in violent and/or criminal behaviours and to score highly on measures of psychopathy (such as selfishness, carelessness, and manipulativeness) than owners of other large dog breeds or small dogs. This suggests that Pit Bulls and other breeds favoured by these types  of owners are more likely to be abused or neglected.

An earlier study by Barnes et al. (2006) yielded similar findings. The researchers compared 166 owners of dog breeds that are considered high-risk for attacking with 189 owners of dogs breeds that are considered low-risk, finding that the owners of so-called high-risk dogs were:

    • 10 times more likely to have criminal convictions
    • 6.8 times more likely to have committed aggressive crimes
    • 5.4 times more likely to have alcohol-related convictions
    • 2.8 times more likely to have committed crimes against children
    • 2.4 times more likely to have committed domestic violence crimes

In this study, dogs classified as high risk included Akitas, Chow-Chows, Dobermans, Pit Bulls, Rottweilers, and wolf mixes.

Cunningham (2004) notes that dog-fighting enthusiasts, drug dealers, and gang members often deliberately train their dogs to be vicious, either to intimidate their rivals or to generate income (for example, dog fighting). Such training typically involves abuse, and Pit Bulls are the favoured breed among criminal owners, which is one of the reasons why Pit Bulls have acquired an undeserved reputation as naturally vicious dogs. Owners of attacking dogs are rarely charged, despite high rates of abuse and neglect of animals that attack (according to the National Canine Research Council, owners of attacking dogs were subjected to criminal charges in only about 26% of cases from 2000 to 2012).

*It is likely that abuse is more common in dog attack cases than the findings of Patronek et al. (2014) indicate because the study only includes cases where dogs were known to be abused. Many dogs may be abused without anyone knowing, so the abuse is not reported.

For more dog articles, see the main Dogs page.


    • Barnes, J.E.; Boats, B.W.; Putnam, F.W.; Dates, H.F.; & Mahlman, H.R. (2006). Ownership of high-risk (‘‘vicious’’) dogs as a marker for deviant behaviors: implications for risk assessment. Journal of Interpersonal Violence, 21, pp. 1616-34.
    • Clarke, N.M. (2009). A survey of urban Canadian animal control practices: The effect of enforcement and resourcing on the reported dog bite rate. Master’s Thesis, University of British Columbia.
    • Cunningham, L.T. (2004). The case against dog breed discrimination by homeowners’ insurance companies. Connecticut Insurance Law Journal, 11.
    • Gershman, K.A.; Sacks, J.J.; & Wright, J.C. (1994). Which dogs bite? A case-control study of risk factors. Pediatrics, 93, pp. 913-917.
    • Guy, N. (1999). Canine household aggression in the caseload of general veterinary practitioners in Maritime Canada. Master of Science thesis, Atlantic Veterinary College, University of Prince Edward Island.
    • National Canine Research Council (NCRC). (2014). Summary Report on Dog Bite-Related Fatalities, 2000-2012.
    • Patronek, G.J.; Sacks, J.J.; Delise, K.M.; Cleary, D.V.; & Marder, A.R. (2014). Co-occurrence of potentially preventable factors in 256 dog bite-related fatalities in the United States (2000–2009). Journal of the American Veterinary Medical Association, 1031(243), pp. 1726-1736.
    • Ragatz, L.; Fremouw, W.; Thomas, T.; & McCoy, K. (2009). Vicious dogs: the antisocial behaviors and psychological characteristics of owners. Journal of Forensic Sciences, 54, pp. 699-703.

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