The one problem my daughter's assertive 1 year old boxer service dog in training has is reactivity to other dogs. Not that he wants to fight them, but he's a very easily aroused dog and he gets so excited at the other dogs in class that he can be very unruly when in proximity to other dogs. And he's rude, lol. It's frustrating, I know. I really like the facility we use. The instructor works with you individually on problem behaviors. Mr. Man continues to take obedience classes and focus classes. Not because he needs to work on the basic stuff, but because it gives them a chance to work on him making good choices and choosing to focus on his handler. There are techniques for this and my daughter would probably be a good one to tell you exactly what they've been doing. I, personally, would not use a prong for this yet. Not without trying other focus and engagement exercises first. Does your facility offer any classes like that? Reactive dog classes maybe?
A prong is not my first choice ever. I have them. I have used them in the past. I know many people that use them. The biggest problem, in my opinion, is that far too many people use the prong and see immediate results, but even years later the second the collar comes off the dog is back to doing what it was doing before. That tells me that the dog is collar smart rather than reliably trained. Or that they're reliably trained that they must behave only when they have the prong on. If the dog only behaves and pays attention when the prong is on, then they really haven't learned what you wanted them to learn. Which is to pay attention to you always, even if they have no gear at all on. Sometimes I feel that a prong is a tool for a lazy trainer. Not always, but sometimes. It does get immediate results. Why? Well, because it's uncomfortable. And ultimately the people that use a prong for the life of their dog haven't really achieved a well trained dog if they misbehave when the collar comes off. They're achieved management. Many people are fine with that and that's fine with me. I want more than management for my dogs and that's fine too.
Is the prong painful? That depends. It depends on the brand of collar and how it's used. If you're going to get one, get only Herm Sprenger. Make sure you know how to fit it. Leerburg has a good article and video on this. Used properly the prong should not cause pain. It does, however, cause discomfort when a correction is applied - either a passive correction or an intentional correction. Intentional corrections done by inexperienced people are definitely painful. Nobody should be jerking on the collars. My kid works in an emergency clinic as well as at the shelter. You'd be surprised how many dogs come in with neck injuries from prongs. Sometimes because of too harsh corrections (and cheap collars) and sometimes because people have been idiots and left the collar on the dog when they aren't actively training. Or tied them out with a prong on. That being said, used correctly the discomfort should be minimal. Much less than a choke and often much less than a flat buckle on a dog that pulls relentlessly. I have tried a prong on myself. It is much less painful that a choke. But yes, it's definitely uncomfortable when a correction is applied.
There are other tools you can try. Which ones might work best for you depends a lot on what exactly she's doing. Is she lunging? Does she lunge without warning? Or is she just pulling? I'm not a fan of head harnesses for dogs that lunge. That can cause neck injuries. But if she's not a lunger then I would perhaps try a Freedom Harness and possibly a Perfect Pace head halter. Used together. That all being said ... you have a bad back. It may be that the safest option for YOU is a prong, depending how she reacts to it. Ella and Roy are very soft dogs and a prong is much too harsh for them. Remember that the dog decides what's aversive. Some dogs will find a head halter super aversive and shut down. Some dogs will show increased reactivity and aggression when using a prong. Some dogs are fine with whatever you use. All training is individual to the dog.
Ultimately it's your choice. I can almost guarantee you'd see immediate results with a prong, but it will be because it's punitive rather than because you've actually changed the emotional state of the dog. That's not really training, imo, it's management. And that's just fine if you're okay with that. It is possible to use a prong, train the behaviors you want, and transition away from it. That really should be the ultimate goal for any training tool be it a prong, a no-pull harness, a head halter, or any other tool. I don't count a leash and flat collar as a tool here because most cities have leash laws, so there is no choice.
