Cross-Eyed Rottweiler

A man took his Rottweiler to the vet and said "My dog's cross-eyed, is there anything you can do for him?" "Well," said the vet, "lets have a look at him." So he picks the dog up and has a good look at its eyes. "Hmm," says the vet, "I'm going to have to put him down" "Just because he's cross-eyed?" says the man. "No, because he's heavy," says the vet.