Severe Roaring in a Horse!!

A teen-age mare presented for respiratory noise during exercise and poor performance. The mare had made noise during exercise for the past 2-3 years WITHOUT poor performance. Interestingly, the mare has always been resistant when cantering to the RIGHT! Recently, it was noted that the mare demonstrated signs of exercise intolerance at the canter. During the exam, the mare was asked to canter on a lunge line and she carried her head to the outside of the circle with her nose turned up. After 1-2 minutes of cantering to the right, it became increasingly more difficult for her to catch her breath and she would occasionally cough/gag violently!. 

Figure 1

 The mare was scoped immediately after exercise and complete paralysis of the left arytenoid was discovered (Figures 1-2). During inspiration, the left arytenoid was across mid-line (yellow line) and obstructing at least 50% of the mare's airway (Figure 2).  It is highly likely that during heavy exercise, the increased negative pressure during inspiration would cause the paralyzed arytenoid to completely cover the airway and prevent the mare from breathing! 

Figure 2

In addition, while scoping the horse, the mare tended to displace her soft palate in such a position that the epiglottis was trapped below (Figures 3-4). When this occurred, the mare instantly began to cough/gag until she corrected the displacement! Displacement of the soft palate is not always associated with arytenoid hemipligia but when it does occur may worsen the exercise intolerance.

Figure 3

The prognosis for this mare is dependent on additional evaluation by an equine surgeon and the recommended surgical procedure. If she is a good candidate for surgery and the surgery is a success, there is a good likelihood that she will return to work and perform significantly better than before.