Man's Dead Dog?

A man woke up one morning to find his dog, lying at the foot of his bed, stiff as a board. The dog couldn't be woken, and afraid something was seriously wrong with his beloved pet, he took the dog to the vet. The vet did a quick once-over of the dog, listened to it's heart and said, "Sir, I am afraid your dog is dead." The man, stunned, said," That can't be! he was fine yesterday! Isn't there anything you can do?" The vet thought for a moment, walked out, and brought back a lrage, black cat. He placed the cat next to the dog, and observed its reaction. The cat, as calm as it could be, sat down and promptly began cleaning itself. The vet looked at the man and said, "It's official. your dog is dead." The man, saddened by the turn of events, said, "Well okay, if your sure. How much do I owe you?" "$550." The man was outraged. "WHAT?! That's outrageous! You didn't do anything!" The vet repilied, "Well, it's $50 for the visit, and $500 for the cat scan."