my great uncle had a "screwtail bulldog" (boston terrier) that caught hogs back in open range days. he had to have help, but they said he caught as hard as anything else.
and if you want to hear really strange? a buddy of mine had one old rooster guinea that took up with his dogs. he had a pen at his house and worked his dogs often and that guinea bayed right with the dogs! dont think he ever took him to the woods though
