Poor Rover

Question

Joe took his old dog Rover to the veterinarian.
Once there , the vet said "Put him on the table"
So Joe lovingly placed Rover on the table. The vet grabbed his stethescope and listened to Rover's chest.
"Well", said the vet " I'm sorry, but he's passed away"
"Dead ?" Joe exclaimed "Are you sure - do I need a second opinion?"
"Hang on" said the vet.
The vet left the room and returned with a Siamese kitten. He then waved the kitten under Rover's nose and over his body.
"That's it" said the vet, "he's definitly dead"
"Okay" said Joe "I believe you. How much do I owe you"
The vet pulled a calculator from his pocket, did a few sums then said " Your bill is $450"
"$450" gasped Joe "How did you get that figure ?"
" Well" said the vet "$50 for the consultation fee and $400 for the catscan"