I have a three year old GSD (rescued). Fantastic loving dog.When out walking though, or in the car, he spies another dog and goes off his head .Screaming and totally loses the plot..tried everything ..ignoring to spraying with water..HELP !! lol

I think you need to discover *why* he's behaving like this - does he feel threatened? Does he feel it's his place to gaurd? There must be some kind of reward for the dog to keep up a behaviour like this. Then you can start to treat the cause - and ignoring or spraying do often help, but you have to keep it up, and do it 100% without fail, or the dog will get positive feelings from the one time you let your gaurd drop - and you're back to square one :(