If you let your animals out for a while (dont know how long)

Dogs- Protects your livestock outside. There is a big dog, a medium (basic dog from other HM games, and a small dog. I think the purpose of the size is by level of experience.

Cats- Brings you various seeds(depending on which cat you chose). Black, brown, or white cat.

Bird- Brings you seeds(Mostly flowers and herbs, and no it won't fly away).

Pig- Brings you money(Various amounts I think)