[69wildwitch]

I have a 3 year old German Shepherd/Husky mix named Nanouk. Up until 7 Months ago he was the most playful thing with other dogs. That's all he ever wanted to do--play!! I have been with him to puppy school and then obedience training and a bit of agility since he liked it so much, and once a week we went to a play hour where the dogs simply had a good romp at the dog school. Then at the end of May we met a woman with her 6 month old Australian Shepherd while we were walking off-leash. She was hesitant and asked if it was okay to play, and I said yes. Nanouk sniffed him and the next thing I know was tearing into the little guy. I was shocked. Then it happened at the dog school a couple of weeks later, but "only" with a certain 2 dogs, one was neutered and the other wasn't. (Nanouk at that time was not neutered, it not being the thing to do in Germany so long as the dog's behaviour is fine--I now wonder if I could have avoided this by having him neutered earlier...hindsight....)(he was neutered the end of August, and I have been told it can take up to a year for the hormones to "retreat"). Then he growled and tried to jump at another puppy, 8 months old, while on leash.
Recently he attacked another young one at the dog school. I don't know how I missed the signs, but there it is, and I need help. I don't know which criteria he has for what he likes and doesn't like, but I wish I did. I am working again intensely on the basic commands, but we have always had a problem with his attention being on me and not on anything else. When we are alone or there are few dogs around, he does everything perfectly. It's the stress situations that are the problem. I probably react differently now too when we see a strange dog. I am trying with treats(I don't use them much in regular training)and praise to keep his attention solely on me when we pass a dog. I try not to put the leash on every time we see a dog I categorize as a potential "candidate" since Nanouk starts looking around "what is there to see..." Strangely enough, he plays again now with the neighbor dog that he stopped playing with when he was a year and a half old.
PLEASE tell me there is a way that I can get this behavior out so that he is again a "playful pup". The hormones may be on their way out, but the behaviour is there.