In the proverb quoted in 2 Peter 2:22, which animal returns to its vomit?

Answer: A dog

"A dog returns to its vomit," and "A sow that is washed goes back to her wallowing in the mud."

“Of them the proverbs are true: “A dog returns to its vomit,” and, “A sow that is washed goes back to her wallowing in the mud.””— 2 Peter 2:22 (BSB)