Tip: For pups that will grow to be bigger dogs, a Gentle Leader Head Harness is highly recommended; for dogs of all sizes a Sense - Ation No - Pull Body Harness is recommended. (smartypup.com)
The gentle leader is a uniquely designed head harness that attaches around the snout and behind the back of the head. (mydoglikes.com)
The dog can slip out of the flat collar if s / he pulls back, so bring a leash hooked to a chain, pinch (prong), Martingale collar or a Gentle Leader type head harness to use when you walk the dog. (gsgsrescue.org)