Rottweiler
A man takes his pet rottweiler to the vets because it is cross eyed
Man: My dog is cross eyed
Vet: Let me have a look..*Picks up the dog*
Man: Is he gonna be okay?
Vet: Im gonna have to put him down
Man: COS' HE IS CROSS EYED?
Vet:...No cos he's very heavy