Susie, I have all my dogs on "Gentle Leader Easy Walk" harnesses, not the muzzle type, but the 'horse harness' type. They have been a God send... you can buy them on ebay for less than retail, and I swear by them. They work just like a horse harness, directing shoulders rather than strangling. Here's a link:
http://cgi.ebay.com/PREMIER-Ge...
People ask me how I can walk 5 dogs at a time, and I'm pretty sure these harnesses help make it possible.