Causes of Nose Bleeds (Epistaxis) in Equines
Epistaxis is defined as the presence of blood in the external nares. The amount of blood present may range from small flecks in the normal nasal discharge to large volumes flowing from both nostrils. Blood in the external nares can originate from one or more of a variety of structures. These can include the nasal cavity, paranasal sinuses, guttural pouch, oral cavity, pharynx, larynx, trachea, or lungs. Bleeding in these structures can be caused by a primary disease or mucosal damage.
Bleeding associated with the nasal cavity or paranasal sinuses usually has blood coming from only one nostril and is spontaneous in nature. The mucosa in the nasal cavity is highly vascularized and can bleed easily due to foreign bodies, fungal infections, or cancer. Theses disease processes usually cause only a small amount of bleeding that occurs intermittently. Trauma is another common reason for mucosal bleeding in the nasal cavity. This can be caused by veterinarians when a nasogastric tube or endoscope is placed in the horses nasal passage. This at times can cause mild to profuse hemorrhage. Erosive diseases that affect the paranasal sinuses of horses commonly cause a unilateral, blood tinged nasal discharge. An ethmoid hematoma is an example of this.
Another source of bleeding while the horse is at rest is the guttural pouch. The horse has a guttural pouch on each side of its pharynx. The guttural pouch is a diverticulum of the Eustachian tube that runs from the horses inner ear to its pharynx. Many important nerves and the internal carotid artery run through this anatomic structure. Infections can occur in this area especially those fungal in nature. Fungal plaques may cause erosion of the carotid artery. The horse will initially experience several episodes of minor hemorrhage with fresh blood coming from one nostril that ultimately leads to large volumes of blood gushing from both nostrils.
Most commonly epistaxis occurs bilaterally immediately after strenuous exercise in horses. This is cause by Exercise Induced Pulmonary Hemorrhage (EIPH). This is most commonly recognized in Thoroughbred and Standardbred racehorses. This is likely caused by rupture of small capillaries in the lung alveoli. With normal breathing the blood will travel up the trachea where some may be swallowed and some may drain out the nasal passage resulting in epistaxis. Other less common causes of post exercise pulmonary hemorrhage in horses include a pulmonary abscess or pleuropneumonia.
There are many other uncommon causes of epistaxis in horses including lesions in the oral cavity, pharynx or larynx caused by infectious disease or foreign bodies. Also uncommon are a variety of inherited and acquired coagulation disorders manifesting in epistaxis.
If your horse exhibits signs of epistaxis it is important to have him evaluated by your veterinarian. This is especially true if the bleeding is persistent, severe in nature, or your horse is displaying signs of respiratory distress. Evaluation of your horse will include a careful physical exam including auscultation of the lungs and trachea. An oral exam may also be warranted. Most often an endoscopy of the upper airway is performed when available to visualize all structures in the nasal cavity, larynx, pharynx, guttural pouch, and trachea.
If you have any further questions or would like more information about epistaxis in horses, contact your veterinarian or one of the veterinarians at New England Equine Medical & Surgical Center.
Ashley Taylor, DVM
Jacqueline Bartol, DVM, DACVIM