Abstract
A one-month-old Thoroughbred colt presented with left hindlimb lameness grade 5/5, according to the American Association of Equine Practitioners' lameness scale. The colt started showing signs of lameness two weeks earlier without being involved in an accident. A local veterinarian examined the foal; radiography revealed no significant findings under the hip joint. No improvement was noted after 15 days of non-steroidal anti-inflammatory drugs (NSAIDs) medication. On presentation at our hospital, ultrasonography was performed, which revealed no significant findings in the iliac wings. The foal underwent a computed tomography (CT) scan under general anesthesia. CT revealed bone cysts in the following that could have caused the lameness: the left transverse process of the 5th, 6th lumbar, and the 1st sacrum vertebrae; osteophytes in the auricular surface of the ilium, suggestive of sacroiliac arthritis. The foal recovered smoothly from anesthesia with assistance. The foal was treated with NSAIDs and rested for more than six months. The owner reported that the foal showed no lameness one year later. CT revealed bony changes in the lumbosacral region that were not detected by radiography and ultrasonography, suggesting that CT could be useful for detecting abnormalities in the pelvic region of horses.