Woman brings a duck to Vet. 

Vet says, "Your duck is dead." 

Woman says, "Are you sure?" 

"Yes," says Vet. 

"How can you be sure you've done no tests." 

Vet brings in a Labrador Retriever which sniffs the duck and shakes his head. 

Next, a cat which sniffs the bird and shakes its head. 

 Vet says, "Sorry, but as I said your duck is dead." Vet hands woman a bill. 

She cries, "$820 to tell me my duck is dead!" 

Vet says, "If you had taken my word for it the bill would be $20, but Lab Reports and Cat Scans cost extra!!"