You can't any bigger than an Irish Wolfhound. They are the "Worlds Largest Breed Dog"

He just squeezed into the hyrobath and it took a bottle and a half of shampoo to cover all the surface area before I could massage him. He fluffed up well with the force dryer which removed a lot of loose undercoat. His Mum was happy with the result and all Dad could do was sit back and laugh.

Sandrack Fearghus, b 18.7.06, bred by Gus & Lisa Barrios

He answers to Fearghus, Floyd, Demon Child, Child of Child, in fact he will answer to almost anything... more so if there is food involved.