My name isXXXXX have been working professionally with animals especially dogs in both health and behavioral issues for over 18 years. I have over 14,000 satisfied customers. It will be my pleasure to work with you today.
In order to supply you with the best information, I do need to ask for some additional information. Once I receive your answer, it will likely take me about 30-45 minutes to type up your response. I hope you can be patient.
Does he do the same thing on leash or only off leash?
If he does not do it when on the leash, is he walking by your side then?
It sounds like you may have done some training with him, so how much obedience training has he had?
Is he neutered?
How much socialization has he had with other dogs through the years?
What have you tried so far?
Perhaps you though you responded, but none came through.