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.MSD Vet Manuals
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.MSD Vet Manuals 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.Journal of Vete…
If endoscopy confirms blood originating from the lower airways, BAL cytology is the most sensitive confirmatory test, detecting hemorrhage in >90% of racehorses.MSD Vet Manuals 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.Journal of Vete… Horses with grade 4 EIPH have shorter racing careers than those with grade 0.Journal of the… Moderate to severe EIPH affects approximately 6% of starters.Veterinary Clin…
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.Journal of Vete…+1 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.Journal of Vete… Its use is prohibited in many nations outside the United States, and racing jurisdictions regulate its administration independently of clinical evidence.Journal of Vete…+1
Non-pharmacologic management is appropriate when race-day medication is prohibited or when furosemide is insufficient. In horses with documented moderate-to-severe EIPH, increasing the interval between races and adopting a negative race pace strategy reduce EIPH severity in subsequent races.Veterinary Clin… EIPH is often erratic in severity from race to race, though it is weakly progressive across increasing race starts at the population level.Veterinary Clin…
EIPH should be considered a progressive disease, and repeated hemorrhage induces pathologic changes in small pulmonary airways, alveoli, and surrounding tissues.Journal of Vete… The ACVIM consensus panel makes a strong recommendation that EIPH be treated as a disease rather than a normal physiologic variant.Journal of Vete…
Risk factors to address include racing in cold ambient temperatures and use of bar shoes, both of which increase EIPH risk.Veterinary Clin… Thoroughbreds are diagnosed more frequently than Standardbreds, and prevalence increases with age due to cumulative capillary damage from repeated racing.MSD Vet Manuals
| Entity | Key Diagnostic Feature | Endoscopic Finding | Performance Impact |
|---|---|---|---|
| EIPH | Blood in tracheobronchial tree post-exercise; epistaxis in ~5% | Grade 0–4 hemorrhage in airways | Significant only at grades 3–4 (< 10% of exams) Journal of Vete… |
| Guttural pouch mycosis | Epistaxis at rest or exercise; potentially life-threatening | Mycotic plaques in guttural pouch | Variable |
| Ethmoid hematoma | Unilateral epistaxis; progressive | Ethmoid mass; may extend into nasal passage | Variable |
| Progressive ethmoid hematoma | Recurrent unilateral epistaxis | Expanding ethmoid mass | Variable |
Would you like guidance on the furosemide dosing protocols and alternatives being evaluated for jurisdictions where race-day medication is prohibited?