A 9 year old, neutered male, Old English Sheepdog presented for evaluation of 6 week's duration lameness on the right front leg. The lameness had not been noted to be acute in onset and had not worsened over the 6 weeks. A transient episode of diarrhea one week prior to presentation was the only other history. The dog had a current vaccination history and was on heartworm preventive. Physical examination found a partial weight-bearing lameness of the right front leg. All joints exhibited a normal range of motion. Muscle atrophy was generalized in the right front leg. The mid-right humeral region was thickened and pain was pronounced by direct palpation of the humeral diaphysis.