Which of the following would be a plausible unilateral cause of epistaxis in a horse?

• A. Trauma
• B. GP Mycosis
• C. EIPH
• D. Coagulopathy

Answer: (A)

Unilateral epistaxis usually points to a local source of bleeding in the nasal cavity or nearby structures. Direct trauma to the nasal mucosa or supporting bones is a common and straightforward cause that commonly bleeds from one nostril.

Guttural pouch mycosis can also cause unilateral epistaxis, because the fungus can erode local arteries within the guttural pouch, but this is a more specific, less common scenario and often comes with additional signs related to guttural pouch disease. Exercise-induced pulmonary hemorrhage tends to produce bleeding after strenuous exercise and is usually bilateral, since the bleeding starts in the lungs and travels to the nostrils. Coagulopathy generally leads to more diffuse mucosal bleeding rather than being confined to one side.