Clinical and Diagnostic Aspects of Equine Sinusitis

Sinusitis is the most common cause of unilateral nasal discharge in the horse and can have multiple causes including: primary sinusitis (no underlying reason found for the sinus infection) and sinus disease secondary to dental infection, sinus cysts, sinus neoplasia, mycotic infections, progressive ethmoidal haematomata and trauma. Whilst endoscopy will usually confirm the presence of sinusitis, radiography (or computerised tomography if available) and sinoscopy are more valuable in investigating its aetiology and extent. A thorough oral examination is also essential to assess if dental disease or neoplasia of the hard palate is involved in its aetiology. An increase in pressure in the sinuses will most commonly cause medial deviation of the thinner medial walls of the sinuses (nasal concha). The thicker maxillary bone can also become inflamed or bulge laterally, leading to facial swelling and possible obstruction of the nasolacrimal duct, resulting in epiphora, especially with sinus cysts and sinus neoplasia, but rarely with primary and dental sinusitis. Veterinarians must recognise and differentiate the common and harmless naso-frontal suture exostoses from (frontal) sinusitis swellings. […]