A horse behaviorist is a horse trainer who specializes in training or retraining horses having behaviors that are dangerous to other animals and humans. Depending on the seriousness of the problem, many behaviorists will first work with the horse to get the negative behavior corrected, and then work with the owner. I think it's important to train the owner to understand the causes of the problem, and how to keep it from recurring.
I have found an article on the subject :
I hope this helps