Pit Bull Terrier
Pit bulls have a well-earned reputation as being the most dangerous dog breed of all. They have such a tendency towards aggression that many cities and municipalities have even taken the drastic step of banning them altogether - making the ownership of a pit bull illegal. Pit bulls are also the serial killers of the canine world, in that more than any other breed, their attacks can be as senseless and unprovoked as they are violent. We know of many cases of pit bulls jumping fences to hunt down and kill kids walking down the street, or getting out and fatally mauling children who are playing in their own yards. Such senseless killings are rarely seen in other dog breeds.
If you Google 'Pit Bull Attacks' you'll find dozens of stories of people being mauled. One study found that over a 3 year period, pit bulls killed 52 Americans. (Week, 2010) You can do the math; with an average of 2 dozen or so fatal mailings’ each year among all dog breeds, pit bulls do more than their share of killing. We would strongly advocate against keeping pit bulls in a home with kids, and never under any circumstances let a child interact with a neighbor/family member’s pit bull without constant adult supervision.
Although their owners tend to be a devoted bunch, we would list Rottweilers right alongside pit bulls as the most dangerous dogs to be around children. During one year, 3 children in my preschool class were mauled by dogs - all of them Rottweilers. Thankfully, the most seriously injured only required stitches and facial surgery. In our time tracking fatal mailings of children for safety purposes, it's been our observation that Rottweilers seem to come up as the culprits at least as often as Pit Bulls. So although statistically they may not be the most deadly dog, they are certainly dangerous and at least run a respectable second.