
Hi, one of the diagnosing things they do is to turn one of the dogs back feet over so the pad is facing back & up and the top of the toes are on the floor, dogs automatically pull the foot forward so the pad is down but with DM theydon't do this, hence sarahs comment about sore feet.
My boy wasn't lame but wasn't sound at about 7 yrs, V gradually got worse, he would turn when trotting and his back legs would get in a tangle but it got to the stage when they got mixed up when he was walking and he would stagger till he got them untied.
We let him go at 8 3/4. His front half was fine and 'lets go do something' but the back end was not under his control.
The final descision was when he pooped walking down the hall, I got his collar to get him to finish in one place, he turned round and it was 'O My G where did that come from, it wasn't me, I don't do that.' that happened 3 times in one day and he was SO upset. We got the vet to do a house call the next morning :-(. 11 years ago and I still miss him, he was my first GSD and I had waited 25+ years from when I fell for the breed to when I got him.
We did half think about a 'cart' but in a smallish semi with a step outside back + front and given the time he would have been out of it and just half a dog we felt sleep was the right descision.
Chris