A 6 year old Quarterhorse gelding was presented to the Iowa State University Veterinary Teaching Hospital for evaluation of a left hind leg lameness. The horse had become acutely lame 5 weeks previously. Two weeks of inactivity had significantly reduced the lameness. The horse was then taken on a trail ride during which the lameness reoccurred and had continued until presentation to the Veterinary Teaching Hospital. No previous lameness was reported. The horse was used to work stock and for pleasure riding.