34th Annual Scientific Meeting proceedings

The diagnosis of upper airway noise in the horse begins with obtaining a complete history from the owner, trainer or referring veterinarian. An understanding of the primary presenting complaint is necessary to determine the appropriate cause for the observed noise. Respiratory noise is either inspiratory or expiratory. Recurrent laryngeal neuropathy (RLN) or pathologies involving the arytenoid cartilage typically result in inspiratory noise. Other abnormalities such as dorsal displacement of the soft palate. (DDSP) are generally expiratory. Other important considerations are the duration of the noise, previous treatments performed, and the presence of coughing and nasal discharge.

A complete physical examination should be performed. Auscultation of the heart and lungs should always be performed to rule out atrial fibrillation, EIPH, bronchopneumonia, and pleural effusion. A subjective evaluation of airflow to determine unilateral or bilateral nasal obstruction should be assessed. Laryngeal palpation should be performed to evaluate atrophy of the cricoarytenoideus dorsalis muscle. A subjective assessment of intermandibular width and palpation of the ventral neck muscles is done.

Every horse evaluated for upper respiratory tract noise should have a standing endoscopic examination performed. The author typically starts on the right side unless a left sided obstruction is suspected. This ensures a consistent endoscopic examination is performed. The endoscopic examination should be complete and includes evaluation of the nasal passages, ethmoid turbinates, nasal septum, guttural pouches, hard and soft palate, epiglottis, arytenoid cartilages, dorsal pharyngeal recess, and trachea to the level of the main stem bronchus.

If there is any doubt about the preliminary diagnosis or if nothing obvious is found during standing endoscopic examination exercising (dynamic) endoscopy should be performed. This can be conducted on a high-speed treadmill or with an overground endoscope. It is vitally important that an accurate diagnosis be determined to make sure the appropriate surgical procedure is performed.

Additional diagnostics such as radiography, computed tomography (CT), ultrasonography, and MRI can be performed as needed to rule out a variety of pathologic abnormalities associated with the upper and lower respiratory tract.

During the presentation the following causes of upper respiratory tract obstruction will be briefly discussed: alar fold/ nasal diverticulum collapse, nasal passage obstruction, nasal septum pathology, DDSP, Epiglottic entrapment, RLN, arytenoid chondritis, guttural pouch tympany, and tracheal collapse.