Heres some statistics that I was able to find about the issue on a link when I googled breeds of dogs that kill.
Which Dog Breeds Are More Likely To Kill PeopleBy: otaffy digg
Dog breeds in general have similar characteristics. Some dog breeds are more likely to kill than others and some breeds are more protective of their masters and physical surrounding than others. There has been a 20 year study to determine which dog breeds are more likely to actually kill human beings. This United States study was done for the years 1979 through 1998.
This study tracks 238 human deaths from dog attacks during a 20 year period. 24% of these attacks involved unrestrained dogs off their owners property. 58% of the deaths involved unrestrained dogs on their owners property. 17% involved restrained dogs on their owners property and less than 1% involved a restrained dog off the owners property.
Some of the conclusions of the study are not suprising. Yes, certain breeds are more likely to kill than others. Yes, deaths from dog attack are quite rare. Also it is sometimes difficult to determine the actual breed of a dog. Communities who try to ban specific dog breeds for public safety will find it difficult to define the parameters of what constitutes that breed.
Several factors interact with the dog to enhance the possibility of a human being attacked by a dog besides the breed of the dog. These factors include heredity, sex, early experience, socialization, training, health, reprodcutive status, quality of ownership and victum behavior. Additionally, this study did not look at intervening variable such as was the dog protecting his owner from serious harm or death or was the dog actually protecting himself from serious harm or death.
Male dogs are 6.2 times more likely to bite then female dogs. Sexually intact dogs,both male and female, are 2.6 more times likely to bite than neutered dogs and chained dogs are 2.8 times more likely to bite then unchained dogs.
One suprising conclusion of several studies is the fact that many varieties of dogs have been involved in a fatal human attack for one reason or another. Topping the list of deaths by dog in a twenty year period is the Pit Bull and Pit Bull mix at
66 human deaths. The Rottweiler and Rottweiler mix was responsibe for
39 human deaths. The German Shepherd dog and mix were responsible for
17 human deaths. The Husky type dog was responsible for
15 human deaths as was the Malamute responsible for
12 human deaths. The Chow Chow was responsible for
8 deaths while the Doberman was responsible for
9 human deaths. The Saint Bernard was responsible for
7 human deaths and the Great Dane was also responsible for
7 deaths. The Akita killed
4 people, the
Bulldog 2, the
Mastiff 2, the
Boxer 2 and believe it or not the Labrador Retriever was responsible for
1 death while Lab mixes were responsible for
4 deaths. The following dogs were responsible for killing one human each during these twenty years: The Bullmastiff, Cheasapeake Bay Retriever, West Highland Terrier, Japanese Hunting Dog, Newfoundland, Coonhound, Sheepdog, Rhodesian Ridgeback and cocker Spaniel.
The conclusion that I make from this study is that almost any dog of size can be dangerous, particularly to children. Dogs must be properly trained, supervised, and care must be taken when choosing a breed with the propensity to be aggressive. Most important, keep young children away from male, sexually intact, chained dogs. 
Once again, leaving the humans to continue their behavior over and over again.
