hi yesterday my 1 year olld gsd female was off lead with a 3 year old gsd female who have known each other for ages but the elder one attacked my dog so my dog retaliated but at training tonight with other gsd who she sees every week one dog came close and my dog growled never done that before

Hi there

I have heard that dogs who have had bad experience/s of other dogs can recognise the breed of that dog.  So, if your dog was not to see that breed again, your dog probably would be ok, but if your dog then recognised another GSD it will remember the attack and try to retaliate.

As you go to traning classes it might be an idea to ask the trainer for their advice.

This is natural, unfortantly all the GSD's round here get grumbled at by a majority of dogs because of one nasty (as in a male which attacks bitches) GSD :(

With hard work you may be able to make your dog relise that not all GSD or GSD looking dogs are bad.  Take adivce of a trainer or behaviourist :)