Objective—To determine the accuracy and precision
of dual energy x-ray absorptiometry (DEXA) for measuring
bone mineral density in horses in situ.
Sample Population—12 randomly selected forelimbs
from 12 horses.
Procedure—Metacarpi were scanned in 2 planes and
DEXA measurements obtained for 6 regions of interest
(ROI). Each ROI was isolated and bone density
measured by Archimedes' principle. Linear regression
analysis was used to determine the correlation
between the 2 measurements at each ROI. An additional
metacarpus was measured 10 times to determine
the coefficient of variation for both techniques.
Results—Dual energy x-ray absorptiometry and bone
density were significantly associated at multiple ROI.
The addition of age, weight, and soft tissue or bone
thickness improved these associations. Repeated
measurements had a low coefficient of variation.
Conclusions and Clinical Relevance—Dual energy
x-ray absorptiometry can be used to accurately and
precisely measure the bone density in the equine
metacarpus. Dual energy x-ray absorptiometry
appears suitable for serial in vivo measurement of
bone density of the equine metacarpus. Dual energy
x-ray absorptiometry may be used for studies to evaluate
the effects of diet or drugs on bone density or
density changes from bone remodeling that develop
prior to stress fractures. ( Am J Vet Res 2001;
Objective—To determine whether administration of
glucocorticoids provides additional benefits to environmental
management of horses with recurrent airway
Animals—28 horses with RAO.
Procedure—Horses were classified as having mild,
moderate, or severe RAO. Within each category,
horses were randomly assigned to receive inhaled
fluticasone propionate, inhaled control substance,
or oral administration of prednisone. During the 4-
week study, horses were maintained outdoors and
fed a pelleted feed. Clinical scores, pulmonary function,
results of cytologic examination of bronchoalveolar
lavage fluid (BALF), and adrenal gland
function were determined before and 2 and 4
weeks after initiation of treatment.
Results—Clinical score and pulmonary function of all
RAO-affected horses improved during the treatment
period. After 4 weeks, clinical scores and pulmonary
function of horses treated with a glucocorticoid were
not different from those for the control treatment. In
horses with severe RAO, treatment with fluticasone
for 2 weeks resulted in significantly greater improvement
in pulmonary function, compared with pulmonary
function after treatment with prednisone or
the control substance. Treatment with a glucocorticoid
for 4 weeks and a low-dust environment did not have
any effect on cellular content of BALF. Treatment with
prednisone for 2 weeks resulted in a significant
decrease in serum cortisol concentration, compared
with concentrations after administration of fluticasone
or the control substance.
Conclusions and Clinical Relevance—Environmental
management is the most important factor in
the treatment of horses with RAO. Early treatment
with inhaled fluticasone can help accelerate recovery
of horses with severe RAO. (Am J Vet Res