I've never heard of them being for one specific breed. We sell them at the shelter. I think one would be good for Mikey. It would also help you feel better during your walks. Just leave his regular collar on with his tags on it and put the martingale on over it. That's what my supervisor at the shelter does and what I did with Taggart. But I don't use Taggarts anymore.
Have you ever considered using a harness for him on walks? Does he pull a lot? Even if he doesn't pull a harness would also add a sense of security for you and it doesn't hurt the dog.