Bone Metabolism Markers in Arabian Horses During the First Two Years of Life

Serum markers of bone metabolism were analyzed in Arabian horses from birth through 2 yr. The marker of bone formation utilized was osteocalcin (OC), and the marker for degradation was carboxy-terminal pyridinoline cross-linked telopeptide region of type I collagen (ICTP). Blood samples were taken via jugular venipuncture the day of birth, d 15, d 30, d 45, d 60, and every 30 d thereafter through d 720. Serum was obtained and analyzed for OC and ICTP. Osteocalcin concentrations increased immediately after birth, were variable, and returned to baseline by d 300. By d 330, concentrations of OC began to decrease from d 0 and stayed at this lower concentration through d 510. From d 540 through 720, OC concentrations were similar to baseline. A decrease from baseline (d 0) in ICTP concentrations was seen on d 60, and ICTP continued to decline in concentration through d 720. Therefore, concentrations of OC and ICTP decreased over time as previously reported, and this study characterizes those changes on a monthly basis. Variability and general concentrations for OC and ICTP obtained in this study will provide valuable information for future experimental design and use of these markers in young horses and will aid researchers in determining treatment effects without being confounded by changes in concentrations caused by growth.