A portion of a man's brain is transplanted into a dog without his
permission, and vice versa.  The man finds himself in the body of the
dog.  Now he must find a way to communicate his plight to a reporter,
and protect his body from the guy who did the operation!  He can't write
very well holding a pencil in his mouth!

Eventually, he writes a bunch of symbols such as "!", ";", ":", etc,
(standing for letters of the alphabet) and brings the reporter to look
at them and his message.  The reporter then has him point at letters to
tell his story.  Sadly, he can't get the doctor to reverse the
operation, but the reporter decides to show of the "dog's" talents to
make money.  Eventually, the dog and man are restored to their bodies
naturally.