Most people don't do records by breeds, cause there is so much variation between individuals, so while the strongest dog ever might be one breed the average of his breed might be much weaker, and the fastest by breed average might contain dogs that run slow, playful is incredibly subjective so I don't think you could get somebody to agree on that, most dangerous I guest you could get from attack reports but those aren't 100% accurate since some people report mixes as pure and some don ' t report all bites
Sorry can't give you exactly what you want, but heres some record holding dogs
http://rulingcatsanddogs.com/dog-world-r ...
well fastest dog would probably be a grey hound because they are bred for racing, but the other ones are just stereotypes, any dog can be aggressive if raised incorrectly.
All of these are based on the individual dog itself.
Hell, it could be a mongrel.
Wow .....
