How should I work up and manage a horse with recurrent epistaxis due to EIPH?

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Accepted Answer

Epistaxis in horses is a presenting sign, not a diagnosis — EIPH accounts for only ~5% of cases, so the workup must first rule out guttural pouch mycosis, ethmoid hematoma, and progressive ethmoid hematoma before attributing recurrent epistaxis to EIPH.2 The first diagnostic step is upper airway endoscopy, performed within 30–90 minutes post-exercise when EIPH is suspected, as blood in the tracheobronchial tree is identified in 45–75% of racehorses by endoscopy and in >90% by bronchoalveolar lavage (BAL) cytology.2 Endoscopy also directly visualizes the guttural pouches and ethmoid region, allowing you to rule out mycotic plaques, ethmoid hematoma, and progressive ethmoid hematoma as the source of epistaxis before proceeding with an EIPH-focused workup. Because examinations performed within 30 minutes of racing are likely to underestimate EIPH severity, timing the scope to 30–90 minutes post-exercise optimizes diagnostic yield.4 If endoscopy confirms blood originating from the lower airways, BAL cytology is the most sensitive confirmatory test, detecting hemorrhage in >90% of racehorses.2 Hemosiderophage presence on BAL cytology confirms prior pulmonary hemorrhage even when acute blood is no longer visible endoscopically. EIPH grading drives management decisions. Severe EIPH (grades 3 and 4) is observed in fewer than 10% of post-race endoscopic examinations and substantially impairs performance; lower grades have little to no performance impact.4 Horses with grade 4 EIPH have shorter racing careers than those with grade 0.6 Moderate to severe EIPH affects approximately 6% of starters.5 For confirmed moderate-to-severe EIPH, furosemide is the only pharmacologic agent with demonstrated efficacy, and there is high-quality evidence that it reduces both the incidence and severity of EIPH.17 Race-day furosemide is administered IV at doses up to 0.5 or 1.0 mg/kg IV depending on racing jurisdiction, given 4 hours before racing.7 Its use is prohibited in many nations outside