High-speed treadmill endoscopy findings
All horses developed exercised-induced compression of the base of the
epiglottis from the first phase of induced poll flexion (phase 2), often
with exacerbation during subsequent phases of poll flexion. Compression
was bilateral in 13/18 horses (72.2%) (Figure 1 and 2) and unilateral
in 5/18 horses (27.8%), with equal distribution between left and right
sides (Figure 3 and 4). Bilateral compression was seen in 10 of 11 NSCTs
(90.9%) and in 3 of 7 STBs (42.9%), whilst unilateral compression was
seen in 4 of 7 STBs and in 1 of 11 NSCTs. All horses demonstrated a
unilateral or bilateral inward bulging of the nasopharyngeal wall
adjacent to the compressed side of the epiglottis (green arrows in
figures) during periods of exercise in poll flexion.
One horse (horse nr. 1) also developed moderate ventromedial luxation of
the apices of the corniculate processes during the first phase of poll
flexion after development of epiglottic compression, which persisted
during phases without poll flexion. Two horses developed intermittent
dorsal displacement of the soft palate (iDDSP) (horse nr. 8 and 11) at
the end of the examination protocol (phase 6 and 5, respectively) when
the horses were completely fatigued and could not maintain the trotting
gait and position on the treadmill. This was several minutes after
developing compression of the base of the epiglottis. Two additional
horses developed palatal instability (horse nr. 7 and 9) and MDAF (horse
nr. 12 and 13) respectively, also several minutes after the onset of
epiglottic compression (phases
4-6).