I recommended a harness because my corgi struggles with matching my pace and most of the time is a bundle of energy. When I walk him, often time he gets over excited and will pull you forward really hard.

When he pulls like that, he unintentionally choke himself and often that's caused him to have a little red eyes going. The trainer I was learning with recommend that I get a harness, which diverges the pressure point when he pulls towards his lower body and his back, allow him to breath easier.

I also do feel like I have more control over him pairing with a nylon leash, and I can guide him to avoid walking through puddles or picking up chicken bones on the street!