We had a dog (dachshund/pariah mix) who bit everybody in our extended family at least once during his 16 years on this earth. We never once mistreated him in any way, but he did get run over in Florida and hacked with a machete in Venezuela. He was ornery from birth, however.
I call it the Napoleon/hitler Syndrome. All small/short Dogs seem to have it. dachshund/pariah mix, chihuahua, minature poodles, etc. They attempt to rip out the Achilles tendon to make a person fall down a be on ground level in an attempt to even up the odds...