Thanks for the suggestions, I dont want to muzzle him so I am happy to consider some of the other ideas, he loves his ball and usually wont bother dropping this for another dog but yesterday something triggered him, I am wondering if he was protecting the old boy, so will try walking them separately. I am very nervous when loose dogs approach and wish other dog owners would keep a closer eye on their pets, after all how can they poop scoop if they are not watching them?
I know my dogs aggression is my problem and I will try and overcome it