I've been seeing @TrevorGoldley's posts about getting his dog ready for hiking on the trail with him, and not sure what reflective vest to get, so I thought I'd share this tutorial I found.
Basically you can just take a only reflective vest and recycle it into 1 or 2 dog vests! You need to shape the coat to the dog's back end with darts in order to keep it in place. Where the darts are placed and how many you need depends on the dog's shape. Sometimes one in the center back in the last third of the seam before the tail end is enough, it seems. Maybe play around with a vest cut out of some throw away fabric to get it right before you try it on your vests.