Irish wolfhound, breed of very large hound whose origins may be traced back many centuries in Ireland. The tallest of dogs, it stands about 34 in. (86.4 cm) high at the shoulder and weighs about 140 lb (63.5 kg). Its rough, wiry coat is usually gray in color. Originally bred as a hunter, the Irish wolfhound had become almost extinct by the mid-19th cent. as a result of the gradual disappearance of its natural quarry, the wolf and elk, and the depletion of its native Irish stock by exportation. A Scotsman, G. A. Graham, was largely responsible for the revival of the breed and supervised the writing of its standard in 1885. Today the Irish wolfhound is kept primarily as a companion dog. See dog.