Description: A lively and active mid-sized terrier with deep-set eyes, long sloping shoulders and a narrow head. Their coats are dense and abundant. They are known for their longevity and were originally used for fox hunting and vermin-killing.

Behavior: Highly intelligent, but can be stubborn; likes to bark and dig. They tend to want to be dominant over other dogs. They are affectionate, and devoted to the extent that they can be protective if they feel a member of the family is being threatened.

Tendency to bark: Medium

Level of aggression: Medium

Suitability as guard dog: Medium

(Candidate photo by AP; sketch by Susan Donley, petspictured.com; breed photo by Reuters)