Which Dog Breeds Are Most Likely to Attack?

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Which dog breeds are the most aggressive? The findings of canine aggression studies might surprise you.

Research Findings: The Most Aggressive Dog Breeds

Research conducted by Duffy et al. (2008) to determine the relative aggressiveness of various dog breeds found that:

    • The dogs that were most frequently aggressive toward people included Chihuahuas, Jack Russell Terriers, Australian Cattle Dogs, American Cocker Spaniels, Beagles, and Dachshunds.
    • Dog breeds that were more likely to be aggressive only toward other dogs included Akitas and Pit Bulls.
    • The least aggressive breeds were Golden Retrievers, Labrador Retrievers, Bernese Mountain Dogs, Brittany Spaniels, Greyhounds, and Whippets.

Research conducted by Martinez et al. (2011) found that:

    • The larger the dog, the less likely it was to engage in aggressive behaviours toward people (barking, growling, snarling, lunging, snapping, biting).
    • Male dogs and, in some cases, older dogs were more likely to be aggressive.
    • Breeds classified as dangerous were no more likely to be aggressive than others.
    • Fatjo et al. (2007), in an analysis of 1,040 cases of dog aggression, found that Cocker Spaniels and Catalan Sheepdogs were the most likely to be aggressive.
    • Zickefoose (2013) reports that Bullmastiffs, Boxers, German Shepherds, Rottweilers, and Pit Bulls were most often reported as biters in Calgary, Alberta, but notes that bites from larger dogs are more likely to be reported, which can lead to overestimates of aggression for certain breeds. The breeds least likely to be the subject of bite reports in Calgary included Beagles, Dachshunds, Basset Hounds, and Greyhounds. Breeds falling in the middle of the spectrum included Bulldogs, Poodles, Shih  Tzus, Boston Terriers, Chihuahuas, Pomeranians, Pekingese, Yorkshire Terriers, Pointers, Retrievers, Setters, and Spaniels.
    • Lansberg’s research (cited by Guy, 1999) found that of the purebreds, Cocker Spaniels, Springer Spaniels, Lhasa Apsos, Golden Retrievers, and German Shepherds were the breeds most likely to be treated for aggression.
    • Draper’s (1995) study of canine personality traits in relation to physical and breed features found that the most aggressive breeds, on average, were Chow Chows, Dobermans, Fox Terriers, German Shepherds, Rottweilers, Miniature Schnauzers, Scottish Terriers, and West Highland White Terriers.
    • Guy (1999) found relatively low biting rates for both Golden Retrievers and the much-maligned German Shepherds, whereas Springer Spaniels had the highest bite frequency in Maritime Canada.
    • Gershman et al. (1994) found that German Shepherds and Chow Chows were most likely to attack, and that attacking dogs were typically unneutered males left chained up in yards.
    • In a study of fatal dog bites in Canada, Raghavan (2008) found that Huskies, Rottweilers, and mixed-breed dogs were responsible for the most attacks.

Cunningham (2004) reports on a review of newspaper articles about fatal dog attacks between 1966 and 1980. Of the 74 fatalities identified in the articles:

    • 16 were attributed to German Shepherds
    • 9 to Huskies
    • 8 to Saint Bernards
    • 6 to Great Danes
    • 6 to Pit Bull Terriers
    • 5 to Malamutes

(This review was conducted by physicians Lee E. Pinckney and Leslie A. Kennedy of the Department of Radiology at the University of Texas Southwestern Medical School.)

Sacks et al.’s (2000) research found that Pit Bull types and Rottweilers were responsible for the most bites. However, the fact that this research specifies “Pit Bull type” suggests that victims or witnesses may be simply guessing at the dog’s breed, and that because Pit Bulls have a bad reputation, people may be more likely to assume that dogs of a certain physical type are Pit Bulls.

Problems with Dog Breed Aggression Studies

The trouble with dog attack studies that focus on breeds is that dog attacks causing death or severe injury are uncommon, so there are not usually enough cases to draw any firm conclusions. Dog aggression studies that include all aggressive behaviours provide better insights because they often use larger samples, but they rarely yield information about the severity of attacks or the percentage of dogs in each breed that attack. This is a problem, because if a breed is popular, there are likely to be more members of that breed in the overall dog population, so the breed will account for a larger number of attacks. For example, if there were 1,000 German Shepherds and only 300 Chow Chows in a dog population and 5 German Shepherds and 3 Chow Chows were responsible for fatal attacks, the rate of attack would actually be higher among Chow Chows, but reports would focus on the number of attacks, which would make German Shepherds seem like the breed most prone to violence. Moreover, in both cases, the percentage of attacking dogs would be so small that it wouldn’t be possible to draw any real conclusions about dog breed aggression from the numbers.

Another problem with dog aggression research is that many studies rely on self-report from owners or attack victims, and people may not report incidents for various reasons, or they may not be accurate in their assessments of the attacking dog’s breed. People often misindentify dog breeds even when they aren’t in the midst of a stressful dog attack, and when witnessing an attack or being victimized by an aggressive dog, they are more likely to identify the dog as belonging to a breed that appears regularly in the media, such as Pit Bull or German Shepherd (Cunningham, 2004).

Yet another issue with dog breed aggression studies is that the majority of dogs are mixed breed (only 40% of owners in the U.S. obtain their dogs from breeders or pet stores), so many people don’t actually know the breeds of their dogs (NCRC, 2014). Given how many dogs are of mixed origin, it’s impossible to determine which of the contributing breeds might be the aggressive one (assuming that aggression is linked to breed at all).

A number of studies have used newspaper reports of attacks to gather data, but this is also problematic because news sources are more likely to report attacks by stigmatized breeds such as Pit Bulls, which makes it seem as though Pit Bulls are attacking more often than dogs of other breeds.

An additional problem with canine aggression studies is that they don’t identify situations in which dogs are severely provoked or simply defending their owners (Cunningham, 2004). Such dogs may be mild-mannered in general, but attack if they are being abused or believe that their owners are being harmed. In such cases, self-defense or protection of an owner is mistaken for general aggression.

For more dog articles, see the main Dogs page.


    • Cunningham, L.T. (2004). The case against dog breed discrimination by homeowners’ insurance companies. Connecticut Insurance Law Journal, 11. https://www.animallaw.info/article/case-against-dog-breed-discrimination-homeowners-insurance-companies.
    • Draper, T.W. (1995). Canine analogs of human personality factors. Journal of General Psychology,  122, pp. 241–252.
    • Duffy, D.L.; Hsu, Y.; & Serpell, J.A. (2008). Breed differences in canine aggression. Applied Animal Behaviour Science, 114, pp. 441–460.
    • Fatjó, J.; Amat, M.; Mariotti, V.M.; Torre, J.L.R.; & Manteca, X. (2007). Analysis of 1040 cases of canine aggression in a referral practice in Spain. Journal of  Veterinary Behaviour, 2, pp. 158-65.
    • 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.
    • Lund, J.D.; Agger, J.F.; & Vestergaard, K.S. (1996). Reported behaviour problems in pet dogs in Denmark: age distribution and influence of breed and gender. Preventative Veterinary Medicine, 28, pp. 33-48.
    • Martinez, A.G.; Pernas, G.S.; Casalta, J.D.;  Rey, M.L.S.; & Palomino, L.F.D.L.C. (2011). Risk factors associated with behavioral problems in dogs. Journal of Veterinary Behavior, 6, pp. 225-231
    • National Canine Research Council (NCRC). (2014). Summary Report on Dog Bite-Related Fatalities, 2000-2012.
    • Raghavan, M. (2008). Fatal dog attacks in Canada, 1990–2007. Canadian Veterinary Journal, 49, pp. 577–581.
    • Zickefoose, S. (2013). Calgarians unleash torrent of dog bite reports. Calgary Herald, May 19. http://www.calgaryherald.com/news/calgary/Calgarians+unleash+torrent+bite+reports/8411084/story.html

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