doggy (n.)youdaoicibaDictYouDict[doggy 词源字典]
also doggie, 1825, from dog (n.) + -y (3). Doggy-bag attested from 1965. As an adj. doggy is attested from late 14c., from -y (2). The word has been used in various formations since at least late 19c. to describe the sex act when one partner is on all fours.[doggy etymology, doggy origin, 英语词源]