Border Collie Help, Please!

[juliacornwal]

I have a 3 year old border collie who is lovely at home, extremely friendly and very good with children. He's also very good with dogs that he knows, and is happy to go for walks with them and let them in his house; but when he meets a dog he doesn't know he instantly goes for it. There's no warning, he's just straight in, snarling and snapping.
He's such a loving dog with us, always nuzzling and asking for attention, he never shows violence to anyone who comes to the front door and is wonderful with the grandchildren, but I'm getting scared to take him out now, because I'm frightened to death that he's really going to hurt another dog one day, without the slightest provocation.
Has anyone got an ideas how I can stop this, or even why it might be happening, please? He is a rescue dog, but I know the home he came from and I know he has never been treated badly in his life, by anyone.

[woofgang]

find a behaviourist who is a member of the APBC. DO NOT have anything to do with anyone who talks about dominance, choke or electric collars or cesar milan

[cazzrob]

I agree with woof, a behaviourist is the best thing you can do for your dog, it will take time, training and dedication ( and a few treats ) but you will get there.