Helping out the knight

Sir Edgbert, knight of the realm, was hurrying home on a cold, dark, wet night when, suddenly, his horse suffered a major coronary and died on the spot. All Sir Edgbert could do was collect up what belongings he could and tramp onwards.After staggering for a spell, he decides that he must get alternative transport. Accordingly, he heads for the nearest building which, as luck would have it, is a small farm. He strides up to the door, bangs on it and shouts 'A horse! A horse!. I must have a horse!".The door opens to reveal a young girl. She looks at Sir Edgbert and says, "Your pardon, good night but my father and brothers are returning from the village on the other side of the forest and will not be back before noon tomorrow. They are riding all our horses".Sir Edgbert is saddened by this and says "But I must return home immediately. Have you any idea where I may accuire alternative transportation?".The young girl says "I know of no other horses hereabouts, but sometimes my brothers ride our Great Dane dog when the need arises. Would use of that help?"Sir Edgbert is desperate and says "If I must, I must. Show me the animal". The young girl leads the way around to the back of the farmhouse to a stable. She dissapears inside and returns leading and enormous dogs which is quite of a size for riding. Unfortunately, the dog has seen better days. It's coat is threadbare, it's legs are spindly and it seems to be breathing labouriously.Sir Edgbert looks at the young girl and says, "Surely, you wouldn't send a knight out on a dog like this?"