I wish I could help you out more here. I don't have much experience with prong collars. I know that when used correctly they can be a good training tool. I also know people who use them who give very light corrections, therefore the prong collar itself does no harm to the animal. However, I've never seen or heard of someone using them on a small dog. To me it wouldn't make sense on a small dog. I know if we put one on my mom's Boston he would freak out! He's very sensitive. Sometimes when we're walking him on the regular leash he'll pull himself away from us and sort of give himself a "correction". It scares him to death. He crouches and runs back to our side. I think mainly because he hasn't been leashed very often because he doesn't leave the house very often, so he's kind of afraid of the leash. So I guess my opinion would have to be that prongs aren't necessary on small dogs.
Well I have seen a prong collars work very well. My boss got this dog about 1-2 mo ago and he loves to jump on our laps and into boxes and get up in your face when we eat. He is just all around not a well trained dog. My boss well is not a dog person. She use to put him in a closet when he was bad (a big one with a light on) I got so mad at her so she is taking him to dog training school. He is only 25-35lbs and if he did not have the prong collar he would be all over the place. So I would be for them if used right.
I use a prong collar on my pitbull, Daisy. Its made a huge difference in her behavior. I was at the point where i didnt want to walk her anymore because she pulled so hard.
After i started with the prong collar everything has changed. She doesnt pull anymore. She heels perfectly for me now. Everyonce in a while i try her with out the collar to she how she does and she has been doing 100% better. I dont think i will have to use it much longer.
Currently I'm using the prong collar on two of my three dogs, my dobe and my rat terrier. I only use them when I take them for a walk or something. I definitely need one for Lexie (dobie) because she's really strong and really bad on a leash. It works well, especially when we're at the nursing home. She's very obedient on it and so is Chopper. I'm going to get one for Mollie sometime soon as well. She never did well on a choke chain and I don't like them, especially since I discovered the prong collar. I think it does a LOT less damage to them than does a choker. JMO
I'm with Mafia, 8 pounder and a prong collar, just not setting with me, I know of experienced trainers used the prongs succesfully without injury when done properly, but just dont think i'd approve one for one of mine that small.