"Research shows over 99.9% of all dogs, from all breeds, will never be involved in an attack.  Thus, I also like to say, “If any breed were genetically programmed to attack, surely more than 0.1% of them would.”--Marjorie Darby

Back in 1999 or 2000, researcher Marjorie Darby looked at news stories about dog bites, and separated them into what were reported to be rather simple bites (ie, 'a pit bull looked at me') and those reported as being more serious (ie resulting in more serious injuries - needing stitches, hospitalization, surgery, etc.). 

Ms Darby had a good contact at Toronto Humane Society at the time, who moved on to Toronto Animal Services as an enforcement/investigation agent.  When queried about the number of dog bite cases, and the relative number of those that were more serious than a simple bite she confirmed the general ratio (nearly all reports were simple bites with minor injuries, only a tiny number could be called "serious".)  Based on all of this information, it became clear that there were (and are) very few actual serious dog bite cases in Canada.  There were maybe a dozen serious dog bite cases from across Canada in the year studied.

To err on the side of caution, Darby decided to assume that the real number of "attack" cases was double, triple or more compared with what she had learned, since she didn't have (and no one has) access to the precise number of incidents.  As Janis Bradley says, nobody is counting dog bites, you have to search hospital records for information - which only represent a portion of all bites.

Darby knew that many serious dog bite cases don't end up in the media because of breed bias.  Still, she could only confirm maybe a dozen dog "attack" cases in Canada, nationwide, over a period of about a year.

Not having access to every single dog attack case, she tried to come up with a reasonable percentage to use in discussions about dog attacks.  With a dog population somewhere around 5,000,000 in Canada, 0.1% is 5,000.  That would mean that, in any given year, there would be 5,000 serious dog attacks, if just 0.1% of dogs were involved.

You can further extrapolate to come up with an even more conservative statistic by theorizing a 10-year lifespan for dogs.  It's not a one-to-one ratio, but a simple way to do that is to simply divide by 10.  That leaves the potential for 500 dog attacks per the entire lifespan of every dog in Canada, if just 0.1% of them were to do so.  And based on what was found concerning the the number of serious dog biting incidents, that is still well within the range of the 0.1% figure (i.e.up to 500 attacks in any given year).  (Keep in mind that she only confirmed maybe a dozen or so serious dog attacks in Canada that year - far fewer than the 500 figure.)

The process is the same for the U.S. but we have better estimates about the number of 'pit bulls' there than here in Canada.

There are estimated to be about 65,000,000 dogs in the U.S.*  0.1% is 65,000.  Meaning, in any given year, if 0.1% of American dogs "attacked", there'd be 65,000 attacks, or 178 serious dog attacks every, single day of the year.  Not just bites, mind you, but "attacks".

Hospital data vary greatly, but 800,000 dog bites treated medically is at the extreme high end, and most of the data around 1999-2000 suggested the figure was more like 300,000 or 400,000.  Still, that doesn't tell us anything about severity, just that medical attention was sought. 

Janis Bradley came on board and showed that fewer than 1% of medically-treated dog bites score higher than a "1" (the lowest ranking) in objective hospital injury recording criteria.  Assuming the dog "attacks" make up this 1%, that would mean about 4,000 biting incidents were more serious than a "1", if assuming 400,000 dog bites treated medically that year.  4,000 represents 0.006% of of the 65,000,000 dogs in America.  If you want to do the simple 10-year lifespan conversion, that would be 0.06% of all dogs at any time in an average 10-year lifespan.  That's still well-within the 0.1% generalization.  (It's almost half!)

There are estimated to be about 9 million 'pit bulls' in the U.S.  Darby used a very conservative estimate of 5,000,000 to calculate what 0.1% of 'pit bulls' attacking would mean.  It comes out to about 14 serious attacks, every single day of the year.  Every day that went by where there weren't 14 serious 'pit bull' attacks somewhere in the U.S., that would mean that even fewer than 0.1% of all 'pit bulls' were  involved in a serious biting incident.  Given that 'pit bull' incidents are reported by the media at such a high rate, I would be surprised to learn than so many serious 'pit bull' attacks are being ignored by them, if it is to be alleged that more than 0.1% of 'pit bulls' are attacking people.

You can do the 10-year lifespan calculations on an estimated U.S. 'pit bull' population anywhere from 5 million to 9 million individuals.  None of the calculations suggest anything other than that 99.9% of dogs, or even 99.9% of all 'pit bulls' will NOT be involved in an attack at any time in their lives.

'Pit Bull' Fatality Data

"When it comes to ‘pit bulls’, fewer than 0.1% will ever be involved in an attack at any time in their lives, and even conservative estimates suggest at least 99.99998% of all ‘pit bulls’ have not killed anyone."

When Darby was conducting this research in 1999-2003, there had been approximately 80 human fatalities attributed to 'pit bull' attacks in the previous 30 years or so in the U.S.  9,000,000 'pit bulls' (assuming a 10 year lifespan) would easily translate into 27,000,000 'pit bulls' that existed during that 30-year period.  80 fatalities out of 27,000,000 is 0.0002%. 

While that seems incorrect to Darby, since she recalls at some point, a few years ago confirming it was 4 zeros after the decimal, rather than 3, that's what this calculation concludes.  Nonetheless, we're still talking about, at most, 0.0002% of 'pit bulls' having killed a person in the U.S.  That leaves 99.9998% innocent of the allegation they're all killers. 

When we're talking about such small numbers, Darby would still have no problem saying, "Frankly, I don't know what relevant information is gleaned from the acts of less than 0.0002% of the population.  Whatever it may be, it certainly doesn't conclude anything about the rest.  Again I would also reiterate, if any breed were genetically-programmed to attack, certainly more than 0.1% of them would".  

---

*According to the most recent US census results, there are now an estimated 72 million dogs in the United States.