Left and Right Laryngeal Hemiplegia in horses

The endoscopic images below are from two different horses with similar clinical complaints yet slightly different physical problems. The gelding in Figure 1 presented for significant respiratory noise during the canter (roaring) and resistance when cantering to the right. The gelding was 12 years old and had a history of "roaring" for multiple years.  In Figure 1, it is evident that there is complete paralysis of the left arytenoid process. Under exercise, the paralyzed process tended to cross over mid-line and prevent adequate passage of air.  He was referred to a surgical facility and a "tie back" procedure was performed. Thirty day post-op endoscopy revealed near complete abduction of the left arytenoid (Figure 2)!! The gelding is significantly improved and will likely perform at a higher level than that prior to surgery.

Figure 1

Figure 2

The endoscopic images in Figure 3 and 4 were from a gelding that presented for significant exercise intolerance at the canter in either direction. The initial endoscopic exam revealed complete paralysis of the right arytenoid process (Figure 3). Paralysis of the right arytenoid is much less common than paralysis of the left arytenoid process and is associated with a worse prognosis. Consultation with an equine surgeon determined that the gelding was NOT a candidate for a "tie back" procedure. In an attempt to improve the gelding's airway, a surgical ablation of several components of the larynx was performed. The thirty day post-op endoscopy revealed a significantly improved airway (Figure 4). Prognosis for this horse as a sport horse remains to be determined however his quality of life has significantly improved! These two cases demonstrate the importance of acquiring the correct diagnosis and surgical intervention via an experienced and highly skilled equine surgeon!! Thank you Dr. John Madison (Ocala Equine Hospital)

Figure 3

Figure 4

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.