Why do puppies bite? 🐶 There are a lot of reasons but one big factor is how they were raised with their litter. Why do puppies bite? 🐶 There are a lot of reasons but one big factor is how they were raised with their litter. Puppies from small litters or singletons often get everything they want right away. When they enter a human world with boundaries, that sudden shift can create frustration, and it often shows up through the mouth. Biting isn’t random or “bad” behavior. It’s communication. �