
It is true that many smaller dogs can be, are allowed to be, snappy. But it is also true that a chihuahua is highly unlikely to kill or seriously maim anyone. So yes I may be more likely to be bitten by a small dog, but if I am going to be killed by a dog the chances are very high that it will be a pit bull. So size and type of dog really does matter when talking about dog bites/attacks on humans. The people that bang on about 'deed not breed' are constantly ignoring the facts that certain breeds are capable of, and actually do, kill people.
If you look at the list of people killed by dogs in Amercia you will see that so far this year 2 people have died, both killed by pitbulls. last year 33 people were killed by dogs - 19 by pits, 3 by rotties and 2 by bull mastiffs. None at all by small dogs. 2013, 26 people killed by pitbulls, 1 tiny baby was killed by 2 shibas but they would have a hard time killing anyone older.