This bloke takes his Rottweiler to the vet and says to him, "My dog's cross-eyed. Is there anything you can do for him?"
"Well," say the vet, "Let's have a look at him."
So he picks the dog up and has a good look at its eyes. After pausing for a while to think, the vet says, "I'm going to have to put him down."
"Just because he's cross-eyed?" exclaims the bloke.
"No," replies the vet, "Because he's heavy."