I had a mutt for 17 years. 
He weighed about 25 lbs and had about twenty seven breeds of mini-dog mixed in but thought he was a pit bull. 
That was before the days of neutering so he "got around". 
There even St Bernards that had puppies that were his spittin image. 
He had a motto; "If you can't screw it, piss on it."