I agree about the head collar. We struggled for months trying to correct Zeus and Apollo's pulling with a regular collar. And I didn't want to do a prong collar, so we bought them Halti-collars from Petsmart. (It works like a lead for a horse.) The transformation was nothing short of amazing! Now it's a complete joy walking them (No more sore arms!) It only took them one short walk to get used to having something on their muzzles, but after lots of treats and praise, they decided it was worth it! Since your pup's only 4 months old, I'm sure he would get used to it quickly, too. Good luck!