[fortheDeclaration]

You wonder what cruelty the dog was subjected to that made it so hostile to humans.

[Slings and Arrows]

You wonder what cruelty the dog was subjected to that made it so hostile to humans.

Some dogs, like some people, are born messed-up, but yeah, cruelty is the most probable explanation, IMO.

[PieterCasparzen]

It’s owner did not exert leadership, so the dog assumed leadership.

Then, when the dog exibited aggressiveness, the owner encouraged it (by not correcting it).