Owner Texas Equine Medical Associates Austin, TX, United States
Abstract:
Background: Equine Nasopharyngeal Cicatrix Syndrome is a poorly understood condition resulting in permanent mucosal fibrosis of the laryngopharynx. Affected horses often have decreased performance and may require a permanent tracheostomy. This syndrome uniquely occurs in the Southeastern United States with horses in Texas being more commonly affected. The etiology has not yet been elucidated nor have the histological characteristics been described previously.
Objective: The objective is to describe six cases of Equine Nasopharyngeal Cicatrix Syndrome, symptomatically, endoscopically, and histologically from the acute to chronic stages over a period of ten weeks.
Animals: Six affected horses from one farm had endoscopic laryngopharyngeal biopsies performed at the onset, at 2 weeks post-onset, and at 10 weeks post-onset. One normal unaffected horse was sampled for comparison.
Methods: The horses were sedated, and lidocaine was liberally applied . Flunixin meglumine was administered intravenously. H&E-stained and Masson’s trichrome stained biopsies were examined, and immunohistochemistry was performed for lymphocytic and histiocytic markers.
Results: The most common clinical signs were clear nasal discharge (5/6) and ulceration of the common nasal meatus (6/6). Histologically, lymphoplasmacytic (6/6) and variable eosinophilic (2/6) inflammation was observed in addition to attenuation of the mucosal epithelium initially. Fibrosis of the lamina propria and loss of mucosal glands was noted over time.
Conclusion: Equine Nasopharyngeal Cicatrix Syndrome is an important differential diagnosis to consider in cases of clear nasal discharge, especially when numerous horses are affected on one farm. Characterization of the progression of this syndrome will lay the foundation for future studies.
