Q. I have a Shih Tzu who bites the leash and tries to bite me. I want to my dog to Heel with a harness. Any advice?
A. If your dog is seriously biting or attempting to bite you, seek one-on-one help from an experienced dog trainer or behaviorist. This is true for small dogs as well as larger dogs. Biting is a serious problem that usually gets worse if not addressed. If what you've been doing on your own hasn't solved the biting problem, get professional guidance to stop it.
A properly fitting body harness (snug but not tight) is a comfortable and safe walking “outfit” for a small dog like a Shih Tzu. You could teach her to Heel in a harness, but start by teaching her to simply walk without pulling (less “formal” than Heeling). Do this by letting her walk a bit ahead of you. Stop walking whenever she pulls and stand still until she quits. If she pulls continuously when you stop, start very slowly backing up. This will make her wonder what's going on back there and she'll turn around to look at you, which will take the tension out of the leash. Praise her and start walking again.
If you’re consistent, your dog will discover that pulling makes you stop walking. She’ll want to keep walking, so she'll figure out how to make you go again -- by walking without pulling.
Some dogs pull very hard when the leash is attached to the ring on the back of the harness. If your dog does this, purchase a harness with a ring on the chest side. With this style of harness, when your dog pulls, it will steer her gently to the side when you stop. To walk in the direction she wants, she'll have to let slack into the leash.
After your Shih Tzu can successfully walk without pulling, begin guiding her into Heel position, close beside your left leg. Reward with treats and praise when she “finds” that position. Teach her a cue word for this (“Heel”) and a different word for informal loose-leash walking (“Walk”). That way you can tell her which kind of walking behavior you want.