Ethmoid Hematoma

Ethmoid hematoma is a progressive and locally destructive disease of horses. It is indicated by a mass in the paranasal sinuses, that resembles a tumor but is not neoplastic by any means. The origins and causes of the ethmoid hematoma are generally unknown. Large hematomas usually start within the ethmoid labyrinth, and smaller ones tend to begin on the sinus floor.

The hematoma usually extends into the nasal passage. A growing hematoma causes pressure necrosis of the bone surrounding the hematoma, but only on rare occasions does it cause facial distortion. It is most commonly seen in horses older than 6 years. Mild, persistent, spontaneous, intermittent, and unilateral epistaxis is the most common sign clinically.