I can only go with my own experience. I have three seniors. Future who was 12 in June, Kia will be 11 Jan 1, 2008 and Bones who is 9.5. All three of them run and play as a much younger dog would. Kia has neck / back issues but even she runs like a crazy woman. I am no expert, but what you are describing sounds like it could be early symptoms of LS. I also will be curious to heaar what your vet has to say. Good luck with Gumby!