Yes, you will make it worse with a simple reprimand. The key is desensitization and counter conditioning (D/CC).

Dogs learn by operant and classical conditioning, regardless of the techniques we use (treats, choke chains, soda cans, yelling, violence). If we get good as conditioning trainers, we have it nailed.

You probably know about desensitization – bring the dog (or person) from far away towards the scary object. Stop when the animal seems agitated. Back up until not scared/agressive/reacting. Treat. Continue treating when you approach when the animal is not nervous. Stop treating when undesired behavior appears.

Counter conditioning is kind of like that. When the scary/reactive stimulus is nearby, the dog gets treats. Stimulus away, treats end. Eventually the dog gets the idea that the stimulus causes the treats. Yay! I want that other leashed dog /person /stranger /baby nearby! I get treats!

Soemtimes you can stun the dog’s attention with a sharp “NO” or “EH!” just to break the stare and get it focused on you, but be ready and poised with the treat when the dog focuses on you. The dog could also learn that it must react and hear the “NO” to get the treat! You kinda want it not to get to that point.

GSDs are sensitive and intelligent creatures. It is easy to mis-cue them. Definitely discuss the behavior with the trainer and see what homework he suggests.

I’d consult the trainer, or a behaviourist. I’d also consider having him neutered, if you haven’t already done so.

Choke Chain, this did wonders for me training my Ger. Shep. It seems harsh but my trainer told me it was ok. It only works when you give it a sharp tug, constant pressure is no good.

DONT PULL ON THE LEASH! carry a pop can with pennies in it and shake it hard. it destracts them and the noise scares them. Pulling on the leash can add to the agression. yelling at the dog makes them think “oh mommy or daddy is being loud, I can to”. when they calm down reward the silence with a treat.

pull on the leash and the dog will start obeying you