Dogs like and need consistency, so if you are not allowing your dog to jump on you, everyone in the family and everyone who greets the dog must do the same. You, as an owner, must make sure this happens. It will only confuse a dog if you allow them to jump on some people who say they do not mind, and tell him not to jump on others. Once you decide you do not wish your dog to jump on people you must apply this to everyone at all times unless you give the dog a command to jump. A dog should never jump on a human of its own free will.
If a dog is stressed or afraid, their demeanor and typical behaviors will change. If you see this in your dog (or really any dog you know) you should step back and check on your dog. Are they hurt? Did a new dog come around they don’t know? Has the weather changed? Is it hot outside? When was the last time they had a chance to go outside to pee or poop? 
If a dog is stressed or afraid, their demeanor and typical behaviors will change. If you see this in your dog (or really any dog you know) you should step back and check on your dog. Are they hurt? Did a new dog come around they don’t know? Has the weather changed? Is it hot outside? When was the last time they had a chance to go outside to pee or poop? 
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.
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.

A relatively new invention that will definitely solve this problem is the no jump harness. It works by restricting the movement of the dog’s hind legs so that it can’t jump at all. This should not be a permanent solution but rather something that can be effectively used during training. It should not only stop them from jumping chain link fences, but also from jumping on people and furniture.
You shouldn’t stop this type of jumping. You need to diagnose your dog's issue and remedy that. If your dog is just stressed being in a new situation, you should calmly get them off of you, offer them a treat to calm them down, and have them sit politely beside you until their stress level has subsided (or take them somewhere else so that they can calm down if it is taking a while for them to calm down.) But most of all, please do not just ignore this behavior change. 
3. Because they have been rewarded for this behavior in the past, whether purposely or unknowingly. Some owners may, at one point or another, allowed the dog to jump on them or on their furniture, welcoming their dog's enthusiasm to see them. Other owners inadvertently reward their dogs jumping, simply by doing something good--such as walking or feeding the dog--right after the dog has jumped. Even if they told off the dog for jumping, by providing the dog with a walk or with food, they make the dog connect these positive actions, with a not-so-positive action: jumping! The dog sees thing in a very simple, linear fashion: if he jumps, he'll get to go for a walk--or even better, he'll get fed!
For pups that ambush you and bite your rear end while playing outside, hide a toy or two in the backyard and ask them to find the toy. Bad weather can give puppies cabin fever when they don’t have adequate time outside to run off the energy. Mental stimulation can wear them out, too. Show your puppy a favorite toy and then roll it up inside an old towel and knot it to make a puzzle. Encourage the pup to unravel and get the toy. You can even tie the first toy-in-the-towel inside a second one for more of a challenge to relieve boredom.

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.
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