hyper and disobediant

Question
Hi, I have a blue nose full blooded pit, (well I think he is all pit) I received him almost 3 weeks ago, he is a very smart dog and learns fast, but most of the time does what he wants when he knows better.  He is extremely hyper and very stubborn.  I have been trying to break him of his bad habits that were learned at another home.  Like jumping on the furniture, jumping on people, and always extremely excited and out of control when company comes.  I find my self constantly repeating my commands to him over and over again, but sometime he just refuses to do them.  But he does know, because he does them when he wants his food or treats.  He has also snipping at my hands when trying discipline him. I have been completely stressed out with his hyper personality and lack of following commands.  He is also growling and barking at people before he sees who they are at my door.  And tries to go after certain people outside.  He has not been neutered yet, and I am just finding out he never had any of his shots.  What do I do,  Do I have a bad dog. Should I worry that he may just take my hand off, or over power my by getting away and going after someone. He wasn't taught any discipline in his other home.  Please help

Answer
He doesn't "know better" or he'd be cooperating - dogs are not stubborn as a rule, they are just insufficiently trained.  If you are repeating commands and he is not doing as you ask, I suspect it is because he either doesn't really know what they mean, or doesn't know they mean the same thing in different locations or he hasn't been "proofed" sufficiently.  The best think you could do right now is to neuter the dog and then take him to a positive training class, or work individually with a positive trainer (*not* someone who uses choke chains, prongs, etc. to enforce discipline).  Avoid using physical force with this dog.  Pits are working dogs, so should be highly trainable using the right techniques.  If the dog is out of control in terms of jumping up, and being hyper, he's just an adolescent untrained overstimulated boy - so self control exercises can help.  There's a great video by Ian Dunbar on training adult dogs that you can get on Amazon Video on Demand.  The exercises he uses in that video have worked extremely well in our adult and adolescent dog classes to teach dogs how to calm themselves.  Dogs that jump up should be ignored until they calm down, then rewarded for having all fours on the floor.  But, with larger, more powerful dogs, you may want to crate the dog when guests first arrive, instruct them what to do, and wait a while until the dog is calmer before letting him out to greet anyone.  If the dog is food motivated, he's trainable - that's good!  But, you as the handler need to learn how to use food correctly in training.  It's not used before you ask for a behavior, it's used to reinforce the behavior after the dog does it.  Some good free lessons can be found at www.clickerlessons.com.