Abstracts | EQUINE
Associations between the radiographic appearance
of vascular channels in proximal sesamoid bones,
their microstructural characteristics and past racing
performance in Thoroughbreds
Kristen A. Lloyd Babatunde A. Ayodele Peta L. Hitchens Cathy Beck Eleanor J. Mackie Robert C. Whitton
Background
Abnormalities in vascular channel appearance within
the proximal sesamoid bone (PSB) are the most common
findings in Thoroughbred yearling presale radiographs
and are often evaluated on radiographs of adult
racehorses. Despite this, their pathogenesis and clinical
significance are poorly understood, and associations
with racing performance are inconsistent.
Objectives
To determine microstructural characteristics of the PSBs
associated with the radiographic appearance of vascular
channels using microcomputed tomography (µCT) and
to determine associations with past racing performance
in mature horses.
All PSBs had at least one vascular channel (mean 3.6
± 0.89) observed on µCT originating from the abaxial
border, yet in only 63.6% (75/118) were channels
observed radiographically. Proximal sesamoid bones
with a higher bone volume fraction (odds ratio [OR]
1.08; 95% confidence interval [CI] 1.01‐1.15; P = .03) and
wider channel diameter (mm) on µCT (OR 20.67; 95% CI
3.29‐130.00; P = .001) were more likely to have vascular
channels identified on radiographs. Greater radiographic
channel number (OR 0.96; 95% CI 0.92‐1.00; P = .04) and
channel diameter (mm; OR 0.96; 95% CI 0.92‐1.00; P =
.04) were associated with fewer career placings.
Main limitations
Radiographs of isolated bones avoided the normal
superimposition of tissue encountered in the live horse.
Study design
Cross‐sectional.
Methods
Results
Conclusions
One pair of PSBs were isolated from a forelimb of 59
Thoroughbred racehorses undergoing post‐mortem
examination. Each PSB (n = 118) was radiographed,
assigned a vascular channel grade using previously
published and novel grading systems, then imaged
using µCT. Associations between radiographic, µCT and
performance variables were investigated with uni‐ and
multivariable generalised linear models.
The ability to identify vascular channels radiographically
indicates widening of channels and densification of the
PSB. More radiographic channels and greater channel
diameter were associated with similar or poorer
measures of past performance, suggesting that these
changes are not desirable.
• Volume 22 Issue 01 | March 2020 •
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