In a horse with left recurrent laryngeal neuropathy, abduction of the
arytenoid cartilage on the affected side of the larynx cannot be
achieved, causing progressive collapse of the arytenoid cartilage and
vocal cord into the airway as negative inspiratory pressure increases.
This produces airflow limitations that result in more rapid development
of hypoxemia, hypercarbia, and metabolic acidosis, causing early fatigue
and poor performance. Horses with left recurrent laryngeal neuropathy
have a history of upper airway obstruction during exercise, including
abnormal inspiratory respiratory noise and exercise intolerance. This
noise is the result of air turbulence created as air passes over the
affected vocal cord and ventricle, which acts as resonators. The DHLCP
caudal and cranial device's are placed between the cricoid and the
arytenoid cartilages and will permanently abduct the affected arytenoid
cartilage. Once abducted sufficiently, it will provide unobstructed
respiration during exercise, but not so much that saliva, food, and water
are aspirated during swallowing.