Stories and art of medieval European hunts feature greyhounds of all sizes, including very large hounds described as "rough-coated greyhounds."
The 1300s definitive guide to hunting, Livre de Chasse by Gaston Phoebus, shows different kinds of hunting dogs:
Note the large "rough-coated greyhound," top left, and compare with the smaller greyhounds, at center.
Livre de Chasse and another Middle Ages work, Le Roman de déduis, describe the ideal hunting greyhound:
"Muzzle of wolf, haunch of lion, neck of swan ... eye of sparrowhawk, ear of snake ...
"He had a shoulder like the roe's;
His flank was like the woodland doe's;
Loin of stag; tail of rat;
Thigh of hare and foot of cat."
(From The Art of Medieval Hunting: The Hound and the Hawk, 2003, Castle Books, copyright John Cummins)
Compare with the American Kennel Club breed standard for the Irish Wolfhound which emphasizes that Wolfhounds are a "rough-coated greyhound-like breed." And it's only about 700 years later!