Have a 4 month old puppy . He is amazing at recall and every other thing off the leash when no other dogs around . but the minute he sees another dog we could be 300 metres away across the park he is gone before I can get to him .most of the other dog owners a really good and stop and wait for me to catch up. But a couple of times they just carry on walking and my dog follows. one incident he just carried on walking out of the park and onto the main road with my dog following him obviously my fault but he could have waited till I caught up. Any tricks i can do? . I no he is only young .