The Irish Wolfhound is a very large bred of dog that have been noted to have Roman records dating to the 391 AD period. These dogs were warriors who fought alongside their owners in battle and while hunting. The Irish Wolfhound's game conisted of boar, deer, elk and the cause of the orgin in its name- wolves. At one point, the breed had lost many of its indivuduals due to the lack of game, but was eventually restored to healthier numbers.
http://www.dogbreedinfo.com/irishwolfhound.htm
http://www.akc.org/breeds/irish_wolfhound/