Pitbull-type dogs are the breed most frequently associated with serious bites, but Rottweilers and German Shepherd Dogs also frequently top lists of biting breeds, notes the American Veterinary Medical Association. Assessing what breed of dog is the most dangerous overall is difficult for a number of reasons, including misreporting and differing popularity of breeds based on location.
As of 2015, pitbull-type dogs tend to be implicated the most frequently in serious bite cases, while small breeds such as the Lhasa Apso, Springer Spaniel and Shih Tzu tend to be the most aggressive toward humans overall.
There is some difficulty in interpreting this data, however. Records on bites often misidentify the breed or breeds involved, especially if the dog is mixed. Popularity of certain breeds can also inflate bite statistics; for example, sled dogs top the biting statistics in parts of Canada, where they are much more popular than in other areas of the world. Finally, not all bites are reported. For these reasons, the American Society for the Prevention of Cruelty to Animals takes the position that breed-specific legislation against "dangerous" breeds is unwarranted.