A prong is perfectly fine to use on a small dog. Just because the dog isn't pulling someone into traffic doesn't mean the walks aren't a miserable experience for both dog and owner. Little dogs can do a heck of a lot of pulling, dispite their small-ness. Yes, you can train it using a clicker. You can train it using a prong. You can train it with a clicker AND a prong. You can use a head halter. Harnesses. The list goes on... Prongs are just one way to help an owner train their dog, small or not to stop pulling on leash. There is nothing wrong with useing this on a small dog. They make mini-prongs just for this reason. Bottom line, use what works for your dog.