A doctor had just finished a marathon sex session with one of
his patients. He was resting afterwards and was feeling a bit
guilty because he thought it wasn't really ethical to screw one of his
patients.

However, a little voice in his head said "Lots of other doctors
have sex with their patients so its not like you're the first...".
This made the doctor feel a little bit better until still another
voice in his head said, "... but they probably weren't
veterinarians".