[chivas]

You need to get him back to the vet, weakness that comes on that fast COULD be very bad. Now I said 'COULD' not 'IS', so dont panic. Ive been lucky in the arthritis issues (about the only lucky thing Ive experienced health wise with my rotties) none have every shown any signs of arthritis and 2 have lived to 11 (but passed from OS) and the girl I have now is almost 7 ( 7 on Oct 1 to be exact!!! same as your boy) and she shows no signs either. I try to keep my dogs lean (but roxie was heavy) and all of them have/had regular exercise. But my small 33lb chow mixed had severe arthritis in his spine, I treated him with baby aspirin and Vit C.