Ideally, training your bulldog when and where it is not appropriate to jump should start when he or she is a puppy. Puppies (and mature dogs ) like to jump onto people for attention, so let your dog know that jumping onto you will not glean the attention he or she wants. When your American bulldog jumps onto you or other family members, turn away and fold your arms. When the jumping stops, pet your dog so that the dog understands that staying calm is the way to get affection. Instruct guests to do the same.
If you have a fence, teach your American bulldog not to jump over it. Take your dog out to the yard with a leash and walk toward the fence. Allow him or her to sniff and look around. When he or she starts to jump, say, 'No,' and walk in the opposite direction. Return a minute later and repeat the process. Repeat training sessions of a few minutes a day every day until your dog gets the idea that it is okay to wander near the fence and satisfy his or her curiosity about it as long as there is no jumping.
Teaching your American bulldog to jump on command will let him know when it is appropriate to jump. Set up some hurdles in your backyard. You can buy hurdles designed for dogs or you can be creative about making your own from plywood, tree branches, or even big rocks. Take your dog to the hurdles, acting enthusiastic to let him or her know that what you are doing is fun. Get your dog running fast and run up to the hurdle. If you are athletic you can jump the hurdle yourself. If not, run past close to it. When your dog jumps over, say, 'Jump.' Repeat this a few times until the word is coupled with the actual jump. Keep practicing for a few minutes every day. Dogs have a shorter attention span than people, so a few short training sessions work better than one long one.
American bulldogs are intelligent and need stimulation to keep from getting bored and wanting to leap over the fence and go exploring the neighborhood. Buy some toys and throw them for your dog to catch and retrieve. Have several toys and hide some away for a few weeks. When your dog gets tired of the toys he or she has been playing with, get out some that have been in hiding, and keep rotating the toys so that they seem new and interesting. Tie a piece of rope to a tree so that the end is about ten feet off the ground. Let your bulldog use up its natural desire to jump up and grab the piece of rope harmlessly.
Remember that a tired dog is a happy dog, and one that is not likely to feel the need to jump. Having a playtime every day when you go for a walk or go to a dog park or play in the yard will keep both of you fit. After lots of physical activity your dog will want to come in and take a nap.
If you have tried training your American bulldog on your own and he or she is still bouncing around, it is time to go to a veterinarian or dog trainer. Some communities have inexpensive dog training courses, or you can check with your local PetCo or PetSmart for classes. Private tutoring is also available, so check your local yellow pages. Enjoy your dog.