Page 675 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

650 CHAPTER 3

VetBooks.ir Prognosis not been replicated by experimental denervation
procedures. Dynamic endoscopy has shown that the
The prognosis is good. Recurrence is recognised in a
small percentage of cases managed by simple transec-
obstructions, commonly but not invariably DDSP.
tion of the membranes. Excision of the glossoepiglottic condition is frequently associated with other airway
mucosa can result in chronic coughing due to low- It appears to be associated with loss of the palatal
grade dysphagia in some horses. Iatrogenic trauma to seal, as air leaks from the oropharynx to the naso-
the epiglottis or pharyngeal structures, especially in pharynx. Axial deviation of the right aryepiglottic
standing procedures, is a serious complication and care fold is commonly identified with arytenoid collapse
should be taken to avoid this. Most cases of epiglottic (RLN) and this is predicted by computer modelling
entrapment make a rapid and uneventful recovery. of airflow with RLN.

AXIAL DEVIATION OF THE Clinical presentation
ARYEPIGLOTTIC FOLDS ADAF usually presents as a typical airway obstruc-
tion of the performance horse or racehorse. The his-
Definition/overview tory is of poor exercise performance associated with
This is an important cause of dynamic airway a harsh inspiratory noise. There is no characteristic
obstruction in the racehorse. The condition was not feature of the inspiratory noise. There is no known
recognised before the advent of dynamic endoscopy. breed or gender bias but there may be a higher inci-
dence in young horses (2–3 years old).
Aetiology/pathophysiology
The aetiology of axial deviation of the aryepiglot- Differential diagnosis
tic folds (ADAF) is not known. The condition has All the causes of inspiratory noise and poor perfor-
mance in the racehorse should be considered. Many
experienced clinicians with access to dynamic endos-
3.95 copy consider the noise identical to that associated
with collapse of the arytenoid cartilage with RLN.
Care should be taken with a diagnosis of ADAF
alone, as many cases are associated with other respi-
ratory obstructions.

Diagnosis
Dynamic endoscopy is required to establish a diagno-
sis of ADAF. There is deviation towards the midline,
of one (usually right side) or both of the aryepiglottic
mucosal folds, which extend between the lateral epi-
glottis and the corniculate process of the arytenoid
cartilages (Fig. 3.95). The degree of deviation var-
ies between cases and this determines the degree of
clinical signs and possible treatment options. Other
concurrent URT endoscopic findings include axial
collapse of the vocal cords, left laryngeal hemiplegia,
intermittent DDSP, right laryngeal dysfunction and
dorsal pharyngeal collapse.

Management
Fig. 3.95 Dynamic overground endoscopy of a horse Surgical resection of the aryepiglottic folds is the
with axial deviation of the aryepiglottic folds. treatment of choice for moderate to severe cases