I think I'll try a prong collar for Mika (lab/boxer/rhodie). She will choke herself to death on the choke-chain, the martingdale is what she has on all day for comfort, and the halti has her rubbing her face on me and her paws more than enjoying a walk. The harnesses haven't worked either.

She heels beautifully UNTIL she sees another dog, then she goes beserk.

Our trainer didn't really like prong or choke, but also understood that Mika really wasn't responding to anything. I only got her when she was 4 and she had never had any kind of training. The trainer also allows us to go back for refresher courses without paying, and I'll be doing that in the summer.