Bronchoalveolar lavage hemosiderosis in lightly active or sedentary horses.
Authors: Mahalingam-Dhingra Ananya, Bedenice Daniela, Mazan Melissa R
Journal: Journal of veterinary internal medicine
Summary
# Hemosiderosis in Non-Athletic Horses: A Previously Overlooked Sign of Severe Asthma Hemosiderophages—macrophages containing iron deposits—are traditionally attributed to exercise-induced pulmonary haemorrhage in racehorses and performance animals, yet little clinical evidence exists regarding their presence in lightly worked or sedentary horses with respiratory disease. This retrospective analysis of bronchoalveolar lavage fluid (BALF) cytology from 91 horses referred for respiratory problems (excluding those with strenuous exercise histories) revealed that hemosiderophages were present in a clinically significant proportion, with severe equine asthma (sEA) being a strong predictor of their presence—horses with sEA were 11.1 times more likely to show hemosiderin positivity than those with mild-to-moderate disease. The finding challenges prevailing assumptions about pulmonary haemorrhage in horses and suggests that chronic airway inflammation associated with sEA may drive red blood cell leakage into the alveolar space through different mechanisms than acute exercise-related haemorrhage. For practitioners, this work highlights that hemosiderophages identified during diagnostic BALF sampling should not automatically be attributed to historical athletic work, particularly when airway hyperreactivity or clinical signs consistent with sEA are present; such findings may instead indicate more severe underlying inflammatory airway disease requiring closer scrutiny and potentially more aggressive management strategies. Establishing hemosiderophages as a measurable biomarker of sEA severity could refine diagnostic protocols and help differentiate disease phenotypes in horses presenting with chronic cough and exercise intolerance.
Read the full abstract on PubMed
Practical Takeaways
- •Finding hemosiderophages in BALF of non-athletic horses should raise suspicion for severe equine asthma rather than automatically attributing them to exercise-induced bleeding
- •BALF cytology with Perls' staining may help differentiate between EIPH and asthma-related pulmonary hemorrhage in respiratory cases
- •Clinicians should consider severe equine asthma in the differential diagnosis when hemosiderophages are identified in lightly-worked or sedentary horses with respiratory signs
Key Findings
- •Hemosiderophages were present in bronchoalveolar lavage fluid (BALF) in 91 horses with light or no exercise history referred for respiratory problems
- •Horses with severe equine asthma were 11.1 times more likely to be hemosiderin-positive than horses with mild-to-moderate asthma (95% CI 3.2-38.5, P < 0.001)
- •Hemosiderophages in sedentary/lightly active horses are not solely attributable to exercise-induced pulmonary hemorrhage
- •A previously understudied association exists between hemosiderophages and severe equine asthma pathology