Chased a squirrel into the house, tortured it, bit off its tail, then, when it escaped into a place they could not reach, spent two days in a near-constant barking frenzy.

Leaned down and put their noses to the ground, in order to distract other dogs and, then, rapidly, viciously attacked while loudly barking and making other threatening noises. They did this with any dogs that were larger than themselves.

Chased a dog around, forcing it go back and forth, while angrily barking at it.

Any time they saw anything that appeared to be a threat, even one that was outside, they stiffened, got a mad stare in their eyes and barked and ran around with seemingly limitless energy until they were satisfied.

I would never want to get on the bad side of a small dog.