[Mick Trainer]

Like others have said you have many issues. First thing you should do is do a search here under "hierachy", "dominance" and "Nilf". There will be a huge swag of information there to help you. And whilst that is printing pick up the Yellow Pages and start ringing to find a professional trainer that performs private lessons in your house and who understands, has experience with dominance aggression between dogs, and is not afraid of training dogs with such problems (if they say "oh you have to put him down" hang up the phone as without seeing the dog this is showing their fear). There is simply to much information and actual practical hands on training that you are going to have to perform that any advise here will not go deaply enough into the problem. Yes he is your responsability and now that responsability requires you to find and work with a professional dog trainer. Where abouts are you located? Maybe someone here will be able to recommend a trainer in your area.

If you are concerned about a bite/fight incident now then you must seperate the dog until the problem is getting sorted.

Hope that this helps,

Mick.