Labrador-Retriever bad habit

Question
Hi there,
I am hoping you may be able to help me. I adopted a Labrador-Retriever age (now) 19 months old 3 months ago. He has been overfed and not exercised properly and has got so out of hand that they previous owners could not handle him.  I put him on a vetenary controlled diet and gave him loads of exercise and he now looks great. He was neutered to try to calm him down without success.  He is fine whilst playing "fetch" and is much better on the lead, however, he will suddenly start jumping up at me or anyone else in the vicinity, grabbing arms hands or legs and biting.  It seems that he is also sexually frustrated as he tries to mate with his bed and this is also the most common reason when he jumps up at me.  I am scared that I will have to try to re-home him and IF I had to do this it would break my heart as on occasions he will sit and allow me to make a real big fuss of him.  He trains easily as he fetches, sits, and stays but will not respond to anything when he is out of control.  Please can you give me any advise?  I do love him and he is such a fine example of his breed.
Many thanks.

Answer
It is possible to train a dog to obey commands without training it to see you as the leader.  Other than that, much of what you have doen is the right thing.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm