By Jess Moreno · November 4, 2026
Most harness problems come from measuring a dog while it is sitting. A sitting dog's chest is wider than a walking dog's, so the harness ends up loose where it matters.
With your dog standing, you should be able to slide two flat fingers under every strap, and no more. If you can fit a fist, the harness will twist. If you can barely fit one finger, it will rub.
Check the strap behind the front legs. It should sit a hand's width back from the armpit. Too close and it chafes on every stride, which is the most common cause of hair loss we see.
Then walk. Watch the back clip: if it slides toward one shoulder, tighten the side straps. If your dog stops and looks at you, something is pinching.
