How Should A Dog's Collar Fit?
1. Harnesses were designed for working animals to pull.
Even if your harness pulls from the side, front, or back, you're only communicating with the dog's body, not the dog's brain. It does not give you the opportunity to direct or lead. We need to stop worrying about the possibility of hurting our dog's necks and figure out why the dog is pulling so hard on the leash, instead of simply giving in to it.
2. Absolutely no dog should be walked on a flexi-leash.
Watching the owner today have no control of his dog was a perfect example. He was trying to reel his dog back, but the dog kept getting further and further away from him. There is no reason why your dog needs to be 15 feet ahead of you (or ahead of you at all) on a leashed walk. If you are practicing recall or scent training etc, get yourself a proper long line (one that won't cut or strangle your fingers if you need to pull it back).
3. The fit of your dog's collar is very important.
A collar or training collar should fit fairly snug and high up - right behind the ears. This gives the handler the ability to lead and takes the power away from the dog's powerful neck and body. If the collar is sitting down low at your dog's chest or shoulders, you're then harnessing the power and weight of the dog, which gives you no control when you need it. I find that slip leashes work great for this. It's a leash and collar combined into one tool (shown in the picture). You can purchase one of these for $20 or less. You can set the collar to where you want it and cinch it up tight.
Merry Christmas and Happy Holidays