She BIT her dog?!

She came home incredibly wasted, and instead of picking a fight with me... decided to pick a fight with her dog who was hogging the bed.

She grabbed his leg and flipped him over... just kind of paused and looked at him... deliberated some more while swaying... and bit his leg.

I tore her off of the dog immediately, the dog was yelping and confused. She had this dead look in her eye and did it all over again. And again. And again.

The next morning she claimed she can't remember anything.

What the hell? Has anyone experienced this before? She'd have broken his leg or worse had I not finally separated them into different rooms. I've never seen that before or since.