Equine Pharyngitis Study Guide

Overview and Clinical Importance

Pharyngitis refers to inflammation of the pharynx, a critical component of the equine upper respiratory tract. In horses, the pharynx is uniquely organized with complete separation into nasopharynx and oropharynx, unlike most other domestic species. This anatomical arrangement has significant clinical implications for the diagnosis and management of pharyngeal diseases.

Pharyngeal disorders represent a significant cause of poor performance, abnormal respiratory noise, and dysphagia in horses. The most commonly encountered pharyngeal condition is pharyngeal lymphoid hyperplasia (PLH), which is particularly prevalent in young horses and often associated with viral respiratory infections. Additionally, severe pharyngitis can occur secondary to bacterial infections such as strangles (Streptococcus equi) and viral infections including equine herpesvirus (EHV) and equine influenza virus (EIV).

Anatomy of the Equine Pharynx

The equine pharynx serves as the crossroads of the respiratory and digestive systems. Unlike other species, horses have a complete separation of the nasopharynx and oropharynx due to the unique positioning of the soft palate. The soft palate merges into the walls of the pharynx, creating an interlocking junction with the epiglottis that maintains this separation except during swallowing.