Green’s Dictionary of Slang

(US campus) a combining form indicating one who does something excessively, e.g. party animal.

1983		Eble Campus Sl. Nov. 1: -animal [...] party-animal, study-animal.
1999		Guardian Weekend 12 June 33: She’s just such a theatre animal.
1999		Guardian Guide 5–12 June 29: Its heroine is a society animal whose life never dips below a surface facade of furs, champagne, perfume and parties.