We have a similar problem with our 11 yr old, Josh. With him it seems to be a back problem. Former owner used to let Josh and Jesse jump out of the back of the truck so they both have arthritis in the elbows plus Josh has the back issue. I keep Rimadyl on hand for those times when he can't get up. It really helps him out. If you can pinpoint the cause, the vet may have a better idea of what will help. Dogs getting old stinks! My 13 yr old gal has a tough time keeping her legs under her these days. She's also got a tumor in her neck that we are watching... Somedays I feel like they are all on borrowed time.