Hair of the dog?

[KindleAndCake]

Where does this saying come from? An actual recipe made with dog hair?

There are other weird and wonderful sayings I want answers to, but first is this one.

Storm in a tea cup?

Bobs your uncle?

Hair of the dog comes from an old belief that if a dog bit you that had rabies you would be cured by drinking a medicine with a hair of the dog in it.

Would it be the rabid dogs hair?