“a hair of dog”不能解释为“狗毛”

Even a hair of dog didn't make him feel better.【误译】即使一根狗毛也不会使他觉得好些。

【正确】即使是再喝解宿醉的一杯酒，也不会使他觉得好些。

A Hair of Dog的来由：这个短语的本意是，如果被狗咬伤了，咬伤的部位必须得用从咬人的那条狗身上的狗毛来治疗。

现在，The(A) hair of the dog (that bit you)已经成为一种幽默的用法，指用来解宿醉的酒（an alcoholic drink taken in the morning because it is said to cure illness caused by drinking too much alcohol the night before.）