Objective—To determine effects of treadmill exercise
on subchondral bone of carpal and metacarpophalangeal
joints of 2-year-old horses.
Animals—12 healthy 2-year-old horses.
Procedure—Horses were randomly assigned to the
control (n = 6) or exercised (6) groups. Horses in the
exercised group ran on a high-speed treadmill 5 d/wk
for 6 months. Horses in the control group were hand
walked for the same amount of time. Results of clinical,
radiographic, nuclear scintigraphic, and computed
tomographic examinations, and serum and synovial
concentrations of biochemical markers of bone
metabolism were compared between groups.
Results—Exercised horses were significantly lamer
at the end of the study than control horses.
Radionuclide uptake in the metacarpal condyles, but
not in the carpal joints, was greater in exercised horses,
compared with control horses. Exercised horses
also had a higher subchondral bone density in the
metacarpal condyles than control horses, but such
differences were not detected in the carpal bones.
Conclusions and Clinical Relevance—None of the
diagnostic techniques evaluated was sufficiently sensitive
to detect all osteochondral damage. Computed
tomography and computed tomographic osteoabsorptiometry
were superior to conventional radiography
for detecting small osteochondral fragments.
Nuclear scintigraphy was a sensitive indicator of subchondral
bone change but lacked specificity for
describing lesions and discerning normal bone
remodeling from damage. Newer techniques such as
computed tomography may help clinicians better
diagnose early and subtle joint lesions in horses prior
to development of gross joint damage. (Am J Vet Res