Abstract
This study was undertaken to evaluate the efficacy of different management techniques to grow weanling horses, focusing on bone growth and development. Horses were put into two management regimens, the first in semi-confinement in a dry lot paddock and the second in confinement with forced exercise of 1200 meters at a gallop three times per week. Radiographs, blood samples and physical measurements were taken on days 0, 28, 56, 84 and 112. Radiographs were taken to evaluate both bone density and geometry. Bone density was expressed in radiographic bone aluminum equivalents (RBAE) and geometry as width in millimeters; both measurements were taken 1 centimeter below the nutrient foramen of the left third metacarpal bone (MCIII). Radioimmunoassay was used to analyze serum samples for the carboxy-terminal propeptide of type I procollagen (PICP), a biochemical marker of bone formation. Total bone RBAE increased (P<.05) for all horses from the start of the project to d 112. Similar increases were seen in the dorsal, palmar and medial cortices. The lateral cortex did not become more dense with time (P>.05). There were no differences (P>.05) between treatment groups in the changes in bone mineral density for the total bone, dorsal or palmar cortices. Lateral and medial cortices did show an increase in bone mineral density with treatment[.] Bone size increased (P<.05) in all horses from day 0 to day 112 in dorsal, medial and lateral cortices as well as the lateral-medial width of the medullary cavity. No size difference was seen in the palmar cortex over time (P>.05). Forced exercise resulted in a difference in total bone width in both the lateral-medial and dorsal-palmar aspects. There were also increased PICP concentrations for treatment B (P<.05). Overall, semi-confinement or forced exercise for a confined horse seems to induce relatively comparable changes in density of MC III in weanling horses. Forced exercise resulted in some increase in bone size and probably total bone mass.
Williams, Jessica Leah (2002). Bone growth and development in weanling horses given forced exercise. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -W349.