Hot dog

A man brought a very limp dog into the veterinary clinic. As he lay the dog on the table, the doctor pulled out his stethoscope, placing the receptor on the dog's chest. After a moment or two, the vet shook his head sadly and said, "I'm sorry, but your dog has passed away."
"What?" screamed the man. "How can you tell? You haven't done any testing on him or anything. I want another opinion!"
With that, the vet turned and left the room. In a few moments, he returned with a Labrador Retriever. The Retriever went right to work, checking the poor dead dog out thoroughly with his nose. After a considerable amount of sniffing, the Retriever sadly shook his head and said, "Bark" (meaning "dead as a doornail").
The veterinarian then took the Labrador out and returned in a few moments with a cat, who also carefully sniffed out the poor dog on the table. As had his predecessors, the cat sadly shook his head and said, "Meow" (meaning "he's history"). He then jumped off the table and ran out of the room.
The veterinarian handed the man a bill for $600. The dog's owner went berserk. "$600! Just to tell me my dog is dead? This is outrageous!"
The vet shook his head sadly and explained. "If you had just taken my word for it, the charge would have been $50.  But with the Lab work and cat scan...."