Hi I have a rescue border collie who is 3 he is really obedient in the house and outside ( comes straight away when called, sits & stays whilst you walk away & leave him for a few yards, learnt lots of tricks) until he has sight of another dog. When he see's another dog out on a walk he lunges on the lead gets really frustrated and barks, if he gets close enough he will attack the other dog on or off lead. He is well exercised goes for bike rides & to agility and even when he is ready to drop he still finds the energy to try & attack another dog. I have taken him to a few agility shows to try & introduce him to them before he starts competing but he just walks around trying to nip anything that walks past & barking his head off. I have had a dog behaviourist come out, all she said was I needed to divert his attention to me, which is easier said than done, he has no interest in food, toys or playing when there is another dog around ! Has anybody else had these problems ? if so how did you overcome them ? If anybody has any suggestions on how to start getting him out of this please please please let me know. He is capable of being nice to other dogs as he lives with 2 others & is also fine with some of my friends dogs, but unknown dogs he will attack on site.