Tuesday, May 10, 2011

Response to injury study

As most of my readers are aware, I track-and when I can personally investigate-fatal dog attacks on humans. So when the article “Mortality, Mauling, and Maiming by Vicious Dogs” was published by The Annals of Surgery[1] I had to buy a copy and read through.

Drs. Bini, Cohn and others present the case that Pit Bull attacks are more serious and cause greater injury that other dog bites, and that Pit Bulls should be “…regulated in the same way in which other dangerous species, such as leopards, are regulated.” 

Now that caught my eye.  So I dug through the article and found some serious discrepancies within the research and conclusions.

First, a couple of notes where credit is due; The researchers, citing solid sources, put to bed the myths of a locking jaw and the allegedly terrible force of the Pit Bull bite. They say clearly in the paper “…there is no such thing as a locking jaw mechanism in pit bulls or in any other canine”.  Their comment on the supposedly terrible bite force is “…there is no evidence for the extreme bite force often reported in the applicable literature.” The cited data shows that Pit Bulls can exert about 235 psi pressure with their jaws, as compared to a German Shepherd at 238 psi and a Rottweiler at 328 psi. In comparison, a grey wolf tests out at about 400 psi, and a lion at 600 psi (p. 793)[2].

Yet this good information is diluted by other references, and conclusions based on these references.  Table 3, titled “Characteristics of Pit Bulls” (p 793), contains statements that are simply incorrect. 

First, I am going to use a very generous definition of “Pit Bull” here, one that uses what I call the “reasonable person” idea; what would a reasonable, logical person, basically familiar with dogs, not overly fond of or afraid of Pitt Bulls, assume to be a Pit Bull? This definition is, I admit, very loose, much looser than the definition cited by the paper’s authors.  Their more restrictive definition reads “The term pit bull refers to dogs from the following breeds: American Pit Bull Terrier, American Staffordshire Terrier, and Staffordshire Bull Terrier.”(p. 791 and Table 3, p.793)  This would eliminate a number of the dogs identified in the documented attacks (such as the Dogo Argentino that killed a man in Indiana)[3].  But we will use the looser definition to give everyone the benefit of the doubt.

So let’s look at these “facts” one by one and dissect the issues.

Pit Bulls, according to the paper, are:

1)      “Responsible for 65% of all fatal attacks in 2008”. In 2008 there were 23 total human fatalities from dog attack. 13 of those were identified as Pit Bulls[4]. That is 56.5%, not 65%, a significant difference, and a factual error.

2)      “94% of (Pit Bull) attacks on children were unprovoked”. This statement is pretty accurate regarding all breeds of dogs. Small children do not have the capacity to knowingly provoke a dog. Older kids should be given the benefit of the doubt unless observed tormenting a dog. This statistic is flashy, but irrelevant.

3)      “81% of attacks that occurred off the owners’ property involved Pit Bulls”. Factually incorrect. In 2008, the worst year, three of the four fatal attacks that happened off the owners’ property were Pit Bulls, which is 75%. In 2009 that number was five out of twelve, making 41.6%. In 2010 two of nine off property fatalities involved Pit Bulls, which is 22%.[5] None of this adds up to 81%. 

4)      “One person is killed by a Pit Bull every 14 days”. This line is repeated in the text of the paper. For this to be true, it would require 26 people every year to be killed by Pit Bulls. In 2007, in 18 of 33 attacks the dogs were identified as Pit Bulls, not 26. In 2008 there were 13 total fatal attacks by Pit Bulls, half the required number. In 2009 there were 15, still short of the needed number. In 2010, 18 of 34 fatal attacks were attributed to Pit Bulls. This blanket “statistic” is flashy and grabs headlines, but is incorrect. The paper, in the narrative, does mention that this is based on a limited time period, but a canny researcher can choose a time period during which dog attack human fatalities were caused by Dachshunds; in fact, during 24 days in 2010, 100% of all human fatal attacks by dogs in the US were due to Weimaraner attack. Sweeping statements cannot be accurately based on small slices of reality. The figures on file don’t support this outrageous claim.

5)      “1.5 Pit Bulls are shot to death every day”. To address this I examined the media reports of dogs shot by police from 1/1/2011 to 5/9/2011. There have been 22 dogs reported shot by police during that time period. Only nine of those 22 were Pit Bulls, although a vicious (inherently dangerous?) Lhasa Apso was shot by police in Cape Coral, Florida on February 6th. To meet the standard of killing 1.5 Pit Bulls every day would require, for this period (129 days) that 193.5 Pitt Bulls be shot and killed, or a total of 547.5 per year-every year. The documented total is a few short.  Of course, this is just police shootings, but cruelty cases are a different story and one can’t conclude that animals are vicious just because vicious humans break the law.

6)      “Pit Bulls attack indiscriminately”. All dogs attack indiscriminately-the only dogs that target particular individuals are Police K9s deployed on criminals. A sweeping statement that is as true for Pit Bulls as for Pomeranians, and again a flashy statement that is irrelevant.

This study is also marred by selective presentation of anecdotal “evidence”. The paper begins with the dramatic recitation of a dog attack where the victim was admitted to the authors’ hospital with ultimately fatal wounds. This account details the efforts to save an 11 month old male victim. Sadly, the attack was well covered in the media, with specifics that mirror the account-to a degree. It occurred in March of 2009, and it seems the baby was only seven months old, not eleven as the paper describes. A small error-but a factual error that knocks one more pebble from a crumbling edifice. You would think that an attending physician might just know how old his patient was.

This case is somehow supposed to illustrate the ‘dangers’ of Pit Bulls, yet there is a more extensive background, one that makes the true nature of this attack clear. At least one of these dogs had a previous bite, to a child, and neighbors reported numerous occasions where the dogs had threatened others.  This was a case of a child not properly supervised in the presence of dogs that had exhibited human focused aggression before on multiple occasions and humans that recklessly tolerated that behavior. Breed seems to have been irrelevant; any dog with a history of human focused aggressive display should have been excluded from being unsupervised with an infant.  The child’s grandmother was indicted in his death, but she died of natural causes before the case came to trial.[6]

Another attack described as a typical Pit Bull attack is the attack to a ten year old female that happened in January, 2007. The paper relates that the girl was attacked by a neighbor’s Pit Bull that was usually chained in the neighbor’s back yard.  What the account fails to report is that the child was going to rescue the dog that had become tangled in the fence by his collar and was choking.  The child saw the dog caught in the fence and, since she had played with the dog, asked her mother if she could go help the dog. Her mother agreed, and the child, who wanted to be a Veterinarian when she grew up, went to help.[7] The dog, predictably, was under severe stress; any organism fighting for breath is likely to fight and attack any close object or person to try and survive. That is why owners are taught that, if their dog is in extreme pain or in a fight to cover them with a blanket or, if injured, try to muzzle them before they try and save them in order to reduce the likelihood of human injury. The poor child rushed in to help and the dog thrashing around bit her in the stomach and neck.  Truly a tragic end, but not exactly a Pit Bull crime, eh?  This was a case of a Good Samaritan that died due to the panic of a dying animal.

Further issues? In the paper the authors claim “These fighting dogs were bred and trained not (sic) to display behavioral signals of their intentions so that they would have an advantage in the ring. For this reason, pit bulls are frequently known to attack “without warning”.”.

The idea that the animals were bred to not display behavioral signals is unsupported. I have never seen, in the literature or history of dog fighting, any indication that fighters deliberately bred such signals out of the dogs. Early in my research I hypothesized that dogs involved in fatal attacks might have limited or impaired ability to signal, through normal canine body language, their intentions. That included Pit Bulls, and any other breed that became aggressive enough to kill a human. But like many hypotheses, beginning with the Flat Earth, my working hypothesis was wrong. In evaluating forty dogs that have killed humans I have yet to see even one that did not show normal canine expressive body posture. Not one, regardless of breed.

Regarding dogs in general, I have also, as part of my training experience, behavior evaluation experience, animal disaster response, and work as an Animal Control Director, observed, trained and handled thousands of dogs. I have not seen any Pit Bull type dogs-or any other type dogs for that matter-that did not show expressive canine body signals. That includes dogs that have severe ear and tail crops. Ear cropping and tail docking may affect some of the cues given dog to dog, and dog to human, but at most it would be equivalent to a minor speech impediment. Intentions, postural cues and calming signals are transmitted constantly. They are presented with the ears and tail-and the eyes, nose, mouth, teeth, hackles, stance-it goes on and on. It is my experience that people who say that the dog “just went off with no warning” simply aren’t reading the signs that are there. In those few cases where I was surprised that a dog went off it was clear in the aftermath each time it was me that failed; I either wasn’t paying attention or wasn’t listening. I should have seen it coming.

On p.795 of the paper the authors make the following statement: “The inbred tenacity of pit bulls, the unrelenting manner in which they initiate and continue their attacks, and the damage they cause are the result of both genetics and environment. Therefore, this breed of dog is inherently dangerous.” They then cite five references to support this conclusion.  A bit of back tracking to the references brings this conclusion into serious doubt.

One reference is to the study that exploded the myth that the authors themselves admit destroyed the myth that Pit Bulls have locking jaws; “With regard to the locking jaw theory, although pit bulls are bred to not let go, there is no such thing as a locking jaw mechanism in pit bulls or any other canine (emphasis added)(p.793).

The next reference was previously cited by the authors showing that the biometric advantage of a large jaw (in a generally larger dog) only produced a small difference in bite pressure; “The results of osteological studies of skull and jaw morphology suggest that, as the mass of the dog increases, small differences in mechanics due to skull morphology may produce a theoretical bite force advantage.” (p. 793) This statement refers directly to the mass of the dog, not the breed. Concluding that a larger dog has a slight advantage makes sense and agrees with the previously cited results that shows a Pit Bull falls just below a German Shepherd and a bit more below a Rottweiler in measured bite strength.

The third reference is actually to the study of bite strength that debunked the “..extreme bite force…” myth, which the authors acknowledge on p.793.  If this myth is untrue, how can the authors use the same figures to support “inherently dangerous”?

So to support their conclusion on page 795 that “…this breed of dog is inherently dangerous” three of the five cited references clearly contradict that conclusion. There seems to be a problem with the logic applied by the authors here.

Close to the paper’s end (p. 796) the authors make an interesting comment: “We should state that our study is limited by its retrospective nature and the limited number of case in which the breed of dog responsible for the attack could be determined. This lack of information may compromise the validity of our results (emphasis mine) implicating the pit bull as a major culprit in severe dog bites admitted to our trauma center.” This cautionary statement is certainly advisable; the authors state in their introduction that they only examined 228 bite cases admitted to their hospital. They further clarify that they were only able to identify breed in 82 cases over a fifteen year period. That brings several factors into play. In their overall admission history of 228 bites they could only use 82-just over one third (35.96%). There could be any number of other breeds contained in the remaining 146 cases, cases that could well have brought some other breed to the forefront. The authors establish no evidence to show that the identified 82 bites are representative of the remainder of the intake cases.

Additionally, this sample seems terribly small. The authors cite the figure that “In 2006 alone, more than 31,000 patients required reconstructive surgery as the result of dog attacks.” The study covers dog bites over a fifteen year period. Fifteen years, multiplied by 31,000 patients, give a total of potentially 465,000 patients across the US that would have been admitted in a trauma center and received reconstructive surgery. Yet the authors are basing their conclusions, flawed as they are, on a sample of seventeen thousandths of one percent (0.00017) of the cases across the US. They admit that they might be wrong since their sample is small and heavily selected (by admission to their particular trauma center). Their caution regarding the size of the sample is well founded.
Yet that does not stop them from reaching the conclusion that “These breeds should be regulated in the same way in which other dangerous species, such as leopards, are regulated.”  

Leopards? The authors admit they might have the whole thing wrong, and then want to regulate dogs like leopards? This is a clear case of adding one and one and getting seventeen-or more accurately, seventeen thousandths.

In any objective evaluation of evidence, a researcher must go where the evidence leads, even if they don’t like the destination. In the case of this research study, the evidence has been selected from dubious sources and then massaged to get the authors to a destination even they admit is a stretch. The Annals of Surgery should be embarrassed to publish a paper using questionable sources. Shame on them, shame on the authors, and especially shame on the peer review committee that should have done basic fact checking before publication.


[1] “Mortality, Mauling, and Maiming by Vicious Dogs” John K. Bini, MD, Stephen M. Cohn, MD, Shirley M. Acosta, RN, BSN, Marilyn J. McFarland, RN, MS, Mark T. Muir, MD and Joel E. Michalek, PhD; for the TRISTAT Clinical Trials Group, Annals of Surgery, Volume 253, Number 4, April 2011, pages 791-797
[2] Barr DB. Dangerous Encounters;Bite Force <http:www.nationalgeographic.com/siteindex/customer.html>.
[3] Personal Investigation, Muncie, Indiana, December 2008
[4] Personal analysis, documented fatal dog bite attacks. Period examined 2008, from files.
[5] Personal analysis of documented fatal dog bite attacks. Periods examined as cited.
[6] MySanAntonio.com Online, http://www.mysanantonio.com/default/article/Grandmother-indicted-in-infant-s-death-840717.php, and Houston Chronicle Online, http://www.chron.com/disp/story.mpl/metropolitan/6810731.html
[7] KRGV-TV Online, Rio Grande Valley, Texas; National Canine Research Council, http://nationalcanineresearchcouncil.com/wp-content/uploads/2010/01/NCRC-FDA-2007-TX-San-Antonio1.pdf; and Fatal Dog Attacks LiveJournal, http://fataldogattacks.livejournal.com/6704.html.

5 comments:

  1. Great rebuttal. I have to admit when I heard tragic stories on the news and read them in the newspapers about pitbull attacks, at first I agreed they needed to be banned. Now that I'm a little older and wiser, I see the need for educating humans on being responsible pet owners. I have three dogs and I watch them - their behavior - and I know when to remove them from something that might become a situation. My neighbors on both sides of me have dogs that are not under control and will rush and bark and has even bitten (without breaking the skin) a neighborhood child. Neither of these dogs are pitbulls. One is a chesapeake bay retriever and the other looks to be a shepherd lab mix.
    Thank you for trying to educate the public on this issue.

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  2. Here Here, Jim. Very well written response. I was reading their artical and did the math. Out of 228 cases, they had breed info in 82 cases, they "identified" supposed pits in 29 cases of those 82. The math I used back in school shows that 29 is 12.7% of 228. So "Pits" can be identified as the type of dog in only 12.7% of the cases. Did they go back and analyze the owners of these pits? In my humble opinion, "Therein lies the majority of the problem."

    Oh well, you know what they say "97.5% of all statistics are made up."

    Thank you for your work in debunking these myths.

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  3. Sadly,this just isn't good science! Lies,damn lies and statistics.
    Note to self: avoid San Antonio hospital!

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  4. My friend Kim wrote: "I believe the journal that published this "study" should be renamed "The ANALS of Surgery" because someone clearly pulled this information out of their ***.

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  5. Thank you! As a trainer who works with aggressive dogs, I also took issue with the study's assertion that attacks on children were unprovoked. A child isn't necessarily AWARE of provoking an attack; most dogs don't like being hugged, for example.

    I'd like to have your permission to include your post in my client literature. Feel free to contact me!

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