1. To assert dominance. Whether it's jumping on people or jumping on furniture, both instances illustrate a dog that wants to raise his station in life. By jumping on you or jumping on the couch, he's saying that he's the pack leader--something that you DON'T want to happen, as a dominant dog is much more difficult to train (and can become quite aggressive). In either case, you'll definitely want to institute the proper alpha dog training techniques, if you haven't already.
An L-footer is a great way to stop your dog from jumping over the fence if used a little differently. You’ll want to turn it upside down and use it at the top of the fence. Create the L-shape and securely fasten the short side to the top of the fence and have the rest of the hardware angled towards the yard so that when your pooch looks up they will see fencing.
When a dog jumps on a human of its own free will, it is not "greeting" the human, it is asserting its dominance over the human; it is the dog communicating that it is alpha and/or wishes to own/control the human. A subordinate would never dream of running over and jumping on the alpha dog of the pack. Space is respect and lower members of the pack respect the higher members. If your dog jumps on humans, it does not respect them. Note: when a young puppy jumps on humans it is sometimes its attempt to reach one's face. Puppies need to be taught not to jump up on humans as this behavior will manifest into other meanings as the puppy grows up into an adult dog.
2. Greet your dog on his level! In addition to waiting to greet your dog, you should also greet him in a stooped position, so that he doesn't have to jump up to greet you. Additionally, if you wish to pet or cuddle your dog, do so on his level. This removes the need to jump at any time. PRAISE HIM for not jumping. If he jumps, use the "Off" command until he stops.
To say hello, of course. Puppies are social creatures and happy and excited to greet just about anyone! Jumping, leaping and bouncing are ways your dog shows affection and receives attention. When a puppy is very young, we usually sit on the floor, let them wiggle into our laps and allow them to lick and nuzzle up close to our face. This is OK because we are down at their level.
An L-footer is a great way to stop your dog from jumping over the fence if used a little differently. You’ll want to turn it upside down and use it at the top of the fence. Create the L-shape and securely fasten the short side to the top of the fence and have the rest of the hardware angled towards the yard so that when your pooch looks up they will see fencing.

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.

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