it (animals)

牠 is composed of 牛 (ox) and 也 (snake, also). 也 is a pictograph of a snake, sharing the same origin as 它. Snakes, lacking limbs, are less familiar to humans compared to other creatures, so a character derived from the snake’s form is used as a third-person pronoun. Since 它 represents non-human creatures or inanimate objects, and cattle walk on four legs, 牠 is used to denote the third-person pronoun for four-legged animals.