1. Horses. Past empires were built on horses and outcomes of battles depended on horses. While they may not be the most useful animals nowadays, they sure were useful back then.
2. Raccoons.... i mean... the obvious....
3. Dogs. They have been used in the past and the present. They are used by police and parts of the army. They can sniff out bombs, and find all sorts of different things. Also very good pets. People say that people who have had dogs as pets live longer than people who never had a pet.
None.