14. Jack Russel Terrier

This small terrier began its hunting duties helping its owners pursue foxes in its early years of existence. Extremely hyper and exuberant, these dogs need a lot of stimulation and outside exercise to release all their energy.  Precisely because they are terriers, the characteristics of a Jack Russell include aggression towards other dogs, jealousy, extreme barking, and possessiveness.

15. Dachshund

Popularly known as the “wiener dog” or “hotdog dog,” the Dachshund is a favorite amongst many canine lovers. Beloved for its distinct appearance, what they are not necessarily known for are the fact that they do, in fact, like to bite. Recent research has proven that one in every 5 dachshunds have tried or have bitten a stranger, while 1 in every 12 has snapped at its owner.  Although they are small, they are definitely fiercer than they appear.