Background: There is no objective information reporting the effect of unilateral laser ventriculocordectomy (VeC) on arytenoid abduction or stability. Objectives: To evaluate arytenoid stability and abduction in horses with severe recurrent laryngeal neuropathy (RLN) before and after unilateral laser VeC. Study design: Prospective study in clinically affected client-owned horses. Methods: Sample size calculations indicated ≥7 horses were required. Horses with grade C or D exercising laryngeal function that underwent unilateral laser VeC were included. Exercising endoscopy was performed before and ≥6 weeks after left-sided laser VeC. Arytenoid stability at maximal exercise was calculated by measuring the left-to-right quotient angle ratio (LRQ) of the corniculate processes at the points of maximal arytenoid abduction (expiration) and maximal arytenoid collapse (inspiration). For each horse, means of measurements obtained for four breaths pre- and post-operatively were used for statistical analysis. Results: Eight horses were included: 5 grade C and 3 grade D laryngeal function. The difference in LRQ between inspiration and expiration was lower post-operatively (median 0.039; interquartile range [IQR] 0.032-0.047) compared to pre-operatively (median 0.158; IQR 0.083-0.249; p=0.01) confirming the left arytenoid was more stable following unilateral laser VeC. The degree of improvement was significantly greater for grade D horses compared to grade C horses (p=0.04). The LRQ measured on maximal abduction was also lower post-operatively (median 0.467; IQR 0.444-0.506) compared to pre-operatively (median 0.578; IQR 0.554-0.655; p=0.02) indicating the left arytenoid was less abducted following surgery. Main study limitations: The sample size was small, no racehorses were included and post-operative assessment was conducted at a variable time after surgery. Conclusion: Unilateral laser VeC in grade C and D RLN-affected horses results in slightly reduced left arytenoid abduction but increased arytenoid stability.

Background: Obesity has been associated with human obstructive sleep apnoea and canine brachycephalic obstructive airway syndrome. To the authors’ knowledge the effect of body condition score (BCS) on structures of the oropharynx , nasopharynx and upper airway of the horse has not been investigated. Objectives: To investigate the effect of BCS on tongue area and height, soft palate angle and basihyoid depth in the horse. Study Design: Retrospective, analytical, cross-sectional. Methods: Computed tomographic (CT) images of the head of 44 horses were assessed. DICOM viewing software was used to measure head length, basihyoid-skin depth, soft palate angle (SPA), midline tongue area and dorsoventral height (DVH) of the tongue in two locations. BCS were assigned at the time of CT examinations. Results: Increased BCS led to an increased mean SPA (mean difference=2.56 ˚ ; P=0.019) and increased median basihyoid depth (mean difference=0.246cm; P=0.006). Following adjustments made for the effect of head length on tongue measures, significant correlation was identified between SPA and tongue area (Spearman’s r=0.544; P=0.007); SPA and DVH of the tongue at the level of the hard palate (Spearman’s r=0.562; P=0.004) and SPA and DVH of the tongue at the lingual process of the basihyoid bone (Spearman’s r=0.690; P<0.001). No significant correlation was identified between variables with sex or age of horses. Conclusions: Increased BCS increases SPA and basihyoid bone depth. Increases in tongue size measurements increase SPA. Results from this study warrant further investigation into the clinical significance of the effects of BCS on the upper airways of the horse.