Actually Liz, despite Mr Barker's observations to the contrary, Old Wort never seemed to have any problem with stairs what so ever. Perhaps along with or because of his ability never to flag when the situation arose, he developed muscles that tucked it closer to his body while going up. I never looked closely to see.

However, his method of descent was also the stuff of local legend. When going down, he would tuck his hind feet up under his body and achieving a certain momentum and balance, used only his front feet to go down stairs. No mean achievement given his anatomical proportions.

Here is a picure of Old Wort and his amazing bone