954 Sounds like he has a lot of mixed feelings. The hair standing up on his back means he feels threatened. Could be a mixture of “im going to get you before you get me and frustration from being on the leash and not being able to control his environment. Also, keep in mind that most dogs automatically are one notch more defensive when restrained to a leash – loosh leash walking when he gets better does help him feel less vulnerable. Ultimately the more positive experiences he has the better with other dogs, but just be sure to pick the play dates carefully – since he can have a bad experience at the dog park too which can set him back. Be sure to watch the dogs in the park play first and scan for bullies before letting him in and be cautious of new arrivals once in the park. The prong collar is usually going to not work well in those lunging situations. The prong collar will either snug up on his neck and not be so bad or, if you jerk it, it will cause a sharp correction that may actually throw gasoline into the fire (since it mimics a bite). They are good for gently showing him positions while teaching heel and other commands, but not good for high distractions. A halti-type collar may be better if you first practice the heeling to at least the phase 2 level in low distractions and then try around distractions from a distance first. If he does well – shower on the treats or love to start counter conditioning him to what passing another dog can mean (good things!)