The story
Alteration of hair of the dog, substituting hair with pelt, thus implying far greater quantity.
Etymology from Wiktionary, CC BY-SA 4.0.
pelt of the dog
Today it means: An immoderate, excessive quantity of alcohol drunk the morning after whilst suffering withdrawal symptoms or a hangover, which goes beyond alleviating the complaint to causing drunkenness; compare hair of the dog. Full definition →