A man takes his Rottweiler to the vet. "My dog's cross-eyed," he says. "Is there anything you can do for him?"

"Well," says the vet, "let's have a look at him." He picks the dog up and examines his eyes, then checks his teeth. After a couple of minutes he says, "I'm really sorry but I'm going to have to put him down."

"What!" exclaims the man. "Just because he's cross-eyed?"

"No," replies the vet, "because he's really heavy."