This puppy needs to be examined by a veterinarian. It is very uncommon for puppies to be "missing a rib." You should not be able to tell this just from watching the puppy breath. I am concerned there is another disease process causing difficulty breathing--this may be infection or developmental in nature. Your veterinarian can count your dog's ribs making sure he has the appropriate number and work to diagnose other diseases. "Missing a rib" should not cause this puppy to breath heavily or have a hernia. Please have this puppy examined before things become life threatening.
