My Maggie is 8 years old, 24 lbs and in good shape. We generally go on a 2-3 mile walk each day unless it's raining. Lately I've noticed that she sometimes trips while walking. She won't fall down completely, but she will stumble on one of her front legs but then straighten up right away and continue to walk. She doesn't seem to be in pain. Last time I took her to the vet she felt her legs and didn't feel anything wrong, no signs of arthritis. Do you think she could just be a little clumsy or could it be something more serious? Do any other corgis trip while on walks??
DM usually affects the back legs first, I believe.
Anecdotally, here's one test for DM: with the dog standing, lift a hind paw and pull it backwards, placing it upside-down on the floor, so the top of the foot is touching the ground, as if it were dragging. If the dog does not correct this position promptly, that could be a sign of DM. I did get this from a vet, but remember, this is 3rd-hand layman's information, so if your dog does this, don't freak. Take a deep breath, see your vet.
It doesn't sound like DM to me. I lost my Emma this past August to DM and it does start with the hind end, toe dragging, then odd walking hitch. She may just be going too fast for her legs, she is getting older and not as athletic, but I would certainly keep an eye on it and continue checking it out when you visit the vet. Good Luck!