Wolfhound, family of hunting dogs consisting of three breeds. The borzoi, or Russian wolfhound, was first used by 17th-century Russian tsars to hunt wolves. The Irish wolfhound was first bred by the Celts and later imported to Ireland by the Romans. The Scottish deerhound, a descendent of the staghound, was once used for hunting deer. Wolfhounds are fiercely loyal and can make good companion dogs if they are given enough space for long, unrestricted runs.