I'd also second what Melinda said and use the other post I and others have made as resources for only if nothing is wrong. Often times a dog won't put everything into it with joint problems and that does not always show up on Xrays if its just beginning to be a problem. Also keep in mind that the spine can have changes just like other joints (depending on this dogs age) I had tried for some time to convince my vet to do Xrays on Met's spine and tail. It took him going in as an emergency client seeing another vet at the practice to get the Xrays some two years later. The result was that Met had severe spondylosis. He had already stepped out of harness and was only doing service and hearing dog tasks at that point, but at that point his body was also beginning to shut down. Obviously I am no longer with that vet. This is the severity of reasons why a dog may not want to guide if in fact its been a happy guide dog. Many things can affect them- sore paws, sore shoulder, improperly fitting harness, even training methods that are harsher. Karyn and Thane