Sunday, December 22, 2013

New research on dog bite fatalities

We’ve known for a while what kinds of dogs are at risk of biting humans: not any particular breed, but dogs who are not well socialized and not well cared for. Dogs living in houses with people are much less likely to bite than dogs living outside in yards or on chains.[1, 2] So why is this new paper about dog bite fatalities important?

Patronek G.J., Sacks J.J., Delise K.M., Cleary D.V. & Marder A.R. (2013). 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, 243 (12) 1726-1736. DOI:
Unlike previous researchers, who mostly approached the question of who gets bitten and what kinds of dogs bite by combing through old records, these authors monitored current events and followed up on every dog bite related fatality that was reported, for ten years (2000-2011). They interviewed law enforcement officers who were involved with these cases. They interviewed medical examiners and coroners. They followed current news articles about cases. This is all information that becomes very difficult to find when you’re trying to learn about a dog bite fatality years after the fact. As the authors write:

In our opinion, the present study represents the most comprehensive analysis of factors...associated with dog bites to date. Personal interviews with credible investigators were successfully conducted in 221 of 256 (86.3%) cases... Law enforcement personnel provide first-hand information not reported in the media and often identified errors of fact in the media reports.

Some information was still very difficult to obtain, and the most interesting part of the paper for me may have been the description of the lengths the investigators went to in their attempts to ascertain the reliability of reports of what breed some of these dogs were. They note that “the source of breed descriptors in media reports is usually unknown” and therefore not trustworthy. Interestingly, this paper never put that comment into context, but it is hard to read it without thinking about how challenging it can be to visually identify the heritage of a mixed-breed dogs, and all the implications that this has for news stories which seem to reflexively identify aggressive mixed-breed dogs as “pit bulls.”

In the context of the debate about whether pits get disproportionately named in media reports about dog aggression, this paper provides some interesting fodder. The authors calculated how often media reports contradicted each other: 21.6% of the time in reports about incidents involving single dogs, 36.4% in incidents involving multiple dogs. How often media reports differed from the animal control officer’s report: 34.9% in incidents involving single dogs, 43.3% in incidents involving multiple dogs. In the rare cases when a pedigree or DNA testing was available, that data disagreed with media reports in 7/19 cases for single dog incidents and 7/28 cases for multiple dog incidents.

What this paper found overall was mostly a vindication of what we already believed: there is no single factor that leads a dog to bite a human. But one very important factor is whether the dog is a “family” dog or a “resident” dog. The paper provides some lovely verbiage on the difference:

A resident dog was a dog, whether confined within the dwelling or otherwise, whose owners isolated them from regular, positive human interactions. A family dog was a dog whose owners kept them in or near the home and also integrated them into the family unit, so that the dogs learned appropriate behavior through interaction with humans on a regular basis in positive and humane ways.

Later in the paper, they add:

Dogs that are deprived of human interaction or direction are denied access to accurate information about appropriate behaviors with humans. Consequently, dogs in stressful, potentially dangerous situations or when maltreated may behave in ways primarily to protect themselves.
In other words, dogs who are not given a chance to learn how to interact appropriately with humans may not act appropriately with humans.

The rest of the paper is packed with nice statistics which I am not going to try to reproduce here. Suffice to say I expect to see excerpts from it on slides in presentations about canine aggression for years to come. I do want to explicitly point out that this paper only covered dog bite fatalities, not dog bites alone; fatalities due to dog bites are extremely rare (this paper found 256 in the United States over a 10 year period), whereas dog bites alone are quite common. I think it’s easy when reading this paper to want to extrapolate all this lovely data about the causes of fatal dog bites out to the causes of non-fatal dog bites. That’s understandable but a little dangerous: it usually requires repeated bites to kill a human, so I imagine such an attack to be different from the more common single bite. But I still believe all this data is very relevant to how we keep our dogs and how to prevent bites. The message the authors give is: be responsible with dogs and they will treat you well. Don’t, and you might be on dangerous ground.

[1] Patronek, Gary J., et al. "A community approach to dog bite prevention." Journal of the American Veterinary Medical Association 218.11 (2001): 1732-1749.

[2] CDC. Home and recreational safety. Dog bites.


  1. It's not an objective study put out by dispassionate researchers. It's a biased puff piece put out by pit bull apologists at the Animal Farm Foundation. Their methodology was designed to intentionally obfuscate breed classifications.

    1. Dr. Patronek is a highly respected veterinary epidemiologist. I would hesitate to refer to any article that he was involved in as a "puff"piece. I know you are coming from a different place than I am about pit bulls, and I'd be very interested to see your reasoning about what specifically is flawed in this paper's methodology. I read it closely and found the methodology sound.

  2. Hello there,

    I appreciate the summary of this article. Did the article provide any statistics on the involvement of chained dogs in fatal attacks? The distinction between resident dog and family dog is a good one, in our community there are many dogs that fall in the resident dog category and are chained and pretty much left on their own.


    Alistair Schroff

  3. Hi, Alistair. They don't go into a lot of details about chaining specifically. Here are the only two quotes:

    "Over three-quarters of cases (195/256 [76.2%]) involved dogs kept by their owners as resident dogs rather than as family dogs. In incidents involving resident dogs, those dogs were kept in a manner that isolated them from the humans in the family, such as chained (74/195 [37.9%]); kept isolated in a fenced area, an outdoor pen, or an isolated indoor area (68/195 [34.9%]); or allowed to roam (30/195 [15.4%])."


    "Appropriate, humane, and clear interactions with people provide dogs with information about how to interact with humans in ways that are neither scary nor injurious to the dog or human. This can occur through daily interaction but cannot occur when dogs are reared apart from daily, freely offered (not while chained) human interactions."

    Hope that helps!