FIGURE LEGENDS
Figure 1: Endoscopy image of horse nr. 3, a 3-year-old
Norwegian-Swedish Coldblooded Trotter (stallion) during phase 1 (A/left)
with free head carriage and during phase 4 (B/right) with induced poll
flexion demonstrating compression of the base of the epiglottis (yellow
arrows) along with inward deviation of the left nasopharyngeal wall
(green arrow).
Figure 2: Horse nr. 18, a 5-year-old Standardbred (mare)
demonstrating bilateral compression of the base of the epiglottis
(yellow arrows) during phase 2; the first phase of induced poll flexion
(A). The epiglottic compression is accompanied by simultaneous inward
deviation of the nasopharyngeal walls (green arrow). Once relieving rein
tension and reducing the angle of poll flexion, epiglottic conformation
returns to normal as seen in phase 3 (B). Note the transtracheal
pressure sensor passed through a polyethylene catheter for
simultaneously measuring tracheal pressures.
Figure 3: Horse nr. 15, a 3-year-old Standardbred (stallion) with
a normally appearing epiglottis during phase 1 (A) and unilateral
compression of the left side of the base of the epiglottis (yellow
arrow) with inward deviation of the left nasopharyngeal wall (green
arrow) (B) during poll flexion in phase 2. Note the transtracheal
pressure sensor passed through a polyethylene catheter for
simultaneously measuring tracheal pressures.
Figure 4: Horse nr 4, a 4-year-old Standardbred (mare) in phase 1
(A) with a normal conformation of the epiglottis, and during poll
flexion in phase 2 (B) with left sided compression of the base of the
epiglottis (yellow arrow) and inward deviation of the left
nasopharyngeal wall (green arrow).
Figure 5: An equine larynx/hyoid specimen illustrating the
thyrohyoid articulations (red arrows top picture and bottom left) and
how manual pressure applied ca. 1 cm distal to the thyrohyoid
articulation causes compression of the base of the epiglottis (bottom
right). Note how the vocal folds are visually obscured during epiglottic
compression (bottom right).