Thanks for the advice given. I decided to give obedience classes a go tonight, and i thought we did very well, but as soon as we stepped outside the class and he saw another dog on the lead, his hackles went up and the growling and snarling started. he was fine inside with the other dogs there but once outside !!!!! The medical side is always a possibility, about 8 months ago he was diagnosed with hip displacia, which probably dosen't help matters, but he is on medication for that, which has helped immensely. I will just keep the classes going and see how he progresses mixing with other dogs in a confined area. I will keep you posted.