Long before 狗 became the everyday word for dog, oracle-bone scribes drew this word as a dog seen from the side: a pricked-up ear, an open snout, an arched back rising into a tail curled proudly over its haunches. 犬 later stepped back into formal and literary Chinese, while its shrunken form 犭 slipped onto the left of many other characters — from 猫 (cat) to 狼 (wolf) — most often marking "this is an animal", though a few characters that picked it up long ago, like 状 or 猜, drifted away from that original sense.
A piece of culture
The toil of a loyal dog The classical idiom 犬马之劳 (quǎn mǎ zhī láo) — "the toil of dogs and horses" — is an old, humble way of pledging loyal service: dogs and horses were prized precisely because their whole purpose was faithful work for their master, asking nothing grand in return. You can still hear officials and courtiers in historical dramas use it to swear devotion to a ruler. It is a reminder that in ancient China, dogs were not just pets: they were guards, hunting partners, and even companions buried alongside their owners in Shang-dynasty tombs.
Use it in a real word
犬子
quǎnzǐ · hyun2 zi2
my son (a humble, old-fashioned way to refer to one's own son) — literally "dog child"; you already know 子