Before you answer the door and welcome guests, clip a leash on your canine, preferably to a front-clip harness or head halter, so that he can be controlled in a manner such that he cannot greet if he jumps. When your dog is calm, with all four paws on the floor — which may take up to a few minutes for more excitable dogs — allow him to approach guests and say hello. If he jumps, gently turn and lead him away; wait for calm behavior before approaching again. For particularly excitable dogs, another option is to remove the dog to a contained area before guests come in. An exercise pen or baby gate is adequate containment for many dogs. If you have an athletic or large dog that can easily scale a gate, use a crate or move him to a room with a closed door. Once your dog calms down, clip on his leash and allow him to come out and greet your guests.
Puppies in human households try to lick the weird, flat, usually bald body part we have instead of a muzzle. When a cute little puppy jumps up to lick face, many people can only say “Awwww!” Hey presto! Jumping up has been rewarded. The puppy’s natural inclination is now a learned behavior. Too bad for the dog when he’s nine months old, bigger and less cute, muddying the pinstripes and knocking Granny to the ground.