Last year, my fiancee and I consulted a dog trainer over various behavioral issues we were having with the pups, including separation anxiety, chewing, and what I refer to as "little man syndrome." In addition to some training techniques to implement, she recommended an item decrease their pulling on the leash.
The first thing she recommended was a no pull leash. This leash was essentially a thin long leash with an extra loop on it in the front. It went under their armpits and across their back (behind their shoulders.) If they pulled, the leash would tighten and it would push their shoulders forward, initiating their backwards "breaks."
I noticed that when I used it, Butters would scream because his armpit would get pinched between the clasp and the leash. After a short period of using it, I noticed both dogs had raw scabbed over skin under their armpits. Immediately I got to thinking of ways I could alleviate this from happening, so I put a soft tube over the leash under their arms. It helped a little, but not fully, so I discontinued the use of the leash.