Ventroaxial luxation of the apex of the corniculate process of the arytenoid cartilage in resting horses during induced swallowing or nasal occlusion

Evaluation of Overground Endoscopy Findings in Colombian Criollo Paso Horses

The dynamic upper airway functional (URT) problems of Colombian paso horses (CPH) have not been investigated in literature up to date. These horses perform special walking gaits with high poll flexion of the neck. Our goal is to evaluate the upper airway mechanics in CPH, showing abnormal respiratory sounds and poor performance during exercise. Resting and overground endoscopy was performed in 40 CPHs. Statistical analyses were performed using the sciPy package. One-tailed Fisher exact tests were used to check for positive contingency between each pair of upper respiratory tract disorder (P < .05). Arytenoid cartilage collapse was observed in 35 of 40 cases during exercise. Among these, dynamic laryngeal collapse (DLC) was the most significant finding, but ventromedial luxation of the apex of the corniculate process of the arytenoid and recurrent laryngeal neuropathy was also observed. Dorsal displacement of the soft palate was only detected in 4 of 40 cases. DLC was significantly associated with vocal cord collapse, nasopharyngeal collapse, and medial collapse of the margins of the epiglottis, and medial collapse of the margins of the epiglottis was associated with nasopharyngeal collapse. DLC is only a typical feature in some special breeds worldwide. We suggest that the extensive poll flexion and the relatively small laryngeal lumen and high intensitivity workload are the most important predisposing factors of DLC. Ventromedial luxation of the apex of the corniculate process of the arytenoid was over-represented in our caseload, compared with other studies. Whereas, despite the intensive workload, dorsal displacement of the soft palate was relatively uncommon. We presume that this could also be tailored to the high poll flexion performed during the special gaits.

Exercise Induced Laryngeal Obstruction in Humans and Equines. A Comparative Review

Dynamic obstructions of the larynx are a set of disorders that occur during exercise in equines and humans. There are a number of similarities in presentation, diagnosis, pathophysiology and treatment. Both equines and humans present with exercise intolerance secondary to dyspnea. During laryngoscopy at rest, the larynx appears to function normally. Abnormalities are only revealed during laryngoscopy at exercise, seemingly triggered by increased ventilatory demands, and quickly resolve after cessation of exercise. Lower airway disease (asthma being the most prevalent condition), cardiac disease and lack of fitness are the major differentials in both species. Laryngoscopic examination during exercise should be performed from rest to peak exertion to allow for a comprehensive diagnosis, including where the airway collapse begins, and thereafter how it progresses. Dynamic disorders with most visual similarity between humans and equines are: aryepiglottic fold collapse (both species); equine dynamic laryngeal collapse (DLC) relative to some forms of human combined supraglottic/glottic collapse; and epiglottic retroversion (both species). Quantitative grading techniques, such as airway pressure measurement, that have proven effective in veterinary research are currently being piloted in human studies. Conditions that appear visually similar are treated in comparable ways. The similarities of anatomy and certain types of dynamic collapse would suggest that the equine larynx provides a good model for human upper respiratory tract obstruction during exercise. Thus, close collaboration between veterinarians and medical personal may lead to further advancements in understanding pathophysiologic processes, and enhance the development of improved diagnostic tests and treatments that will benefit both species.

Impact of pharyngeal endoscopic tip placement and water flushing interval on upper respiratory tract disorders in horses undergoing overground endoscopy

BACKGROUND

Endoscopic tip placement in the pharynx and water flushing interval (FI) may affect exercising upper respiratory tract (URT) endoscopic results.

OBJECTIVES

To determine associations between the endoscopic tip position in the pharynx and automated FI with overground endoscopic (OGE) results.

STUDY DESIGN

Randomised balanced 2X5 factorial design.

METHODS

A total of n = 200 horses undergoing OGE were randomly assigned into 10 groups (n = 20/group) of different automated endoscopic FIs (no flushing, 60, 120, 180, 240 s) with the endoscope tip positioned either rostrally (position A) or caudally (position B) in the pharynx. Endoscopic videos were analysed and all URT abnormalities graded using published scales. Disorders with ≤10% prevalence were excluded from the final analysis with only arytenoid asymmetry at exercise (AAex), vocal fold collapse (VFC), palatal dysfunction (PD) and medial deviation of the aryepiglottic folds (MDAF) included. The association of endoscope position and FI with URT disorders was assessed using ordinal regression models with P≤0.05 significant.

RESULTS

Endoscope tip positioning was significantly associated with PD grading (P = 0.002), with 63/100 horses diagnosed with PD in position A and 45/100 in position B. No other significant direct associations between URT disease and endoscope tip position were identified, although interactions between exercise velocity and endoscope position affected MDAF grade. FI was not directly associated with alterations in disorder grading, although interactions between exercise velocity and FI appeared to affect MDAF grade.

MAIN LIMITATIONS

The same horse was not evaluated under each test condition potentially resulting in sample bias. Interactions between disorders were not evaluated. The sample size was insufficient to conclusively explore relationships between all factors and disorder grading.

CONCLUSIONS

Position of the endoscope tip within the pharynx appears to affect grading of PD during OGE examination. Exercise velocity may affect MDAF grade through interactions with endoscope position and FI.

Dynamic respiratory endoscopy of Standardbred racehorses during qualifying races

REASON FOR PERFORMING STUDY

Examination of the equine upper airway during racing has not previously been documented.

OBJECTIVE

To describe the feasibility and appearance of the upper airways by overground respiratory endoscopic examination during racing conditions.

METHODS

Overground videoendoscopic examinations were performed on 46 Standardbred racehorses during qualifying races. Examined horses' speeds were recorded throughout the race with a portable GPS device.

RESULTS

The procedure did not interfere with performance as there were no significant differences in race times between races in which horses were examined with the endoscope in place and prior unexamined races. Airway obstructions during or after the race were documented in 21 horses. Most previously reported causes of upper airway obstruction were observed; surprisingly bilateral ventro-medial arytenoid displacement (VMAD; n = 5) was seen during exercise as frequently as dorsal displacement of the soft palate (DDSP). Although DDSP (n = 10) was the most common diagnosis made, many displacements (n = 5) occurred after the race. Horses that demonstrated DDSP after the race had slower speeds than unaffected horses during the race.

CONCLUSIONS

Racing endoscopy permits the diagnosis of upper airway obstructions without affecting performance. The occurrence of DDSP immediately after exercise may be clinically relevant. During racing VMAD may be an important anomaly.

POTENTIAL RELEVANCE

Racing endoscopy could be used to correlate the sensitivity of diagnostic endoscopy during race-training or treadmill examination. The pathogenesis and significance of VMAD deserves further investigation.