Endoscopically assessed mucus parameters in equine asthma: Relationship to clinical history and cytological findings data.
Authors: Drespling Julia, Berwanger Leonie, Kühn Heike, Schwarz Bianca, Doherr Marcus, Mundhenk Lars
Journal: Equine veterinary journal
Summary
# Editorial Summary Mucus appearance during upper airway endoscopy is a cornerstone diagnostic feature of equine asthma, yet Drespling and colleagues' retrospective analysis of nearly 1600 samples reveals important nuances about how mucus quantity and viscosity relate to disease severity and underlying airway inflammation. Using standardised scoring systems, the researchers found that a mucus quantity score exceeding 2 was associated with a 3.6-fold increased odds of severe equine asthma (SEA) diagnosis, though this threshold did not reliably predict mild to moderate disease—a distinction with real implications for case stratification during endoscopic examination. Weak but statistically significant correlations emerged between both mucus scores and neutrophil counts in bronchoalveolar lavage fluid, supporting the mechanistic link between mucus accumulation and active inflammatory infiltration, whilst associations with age, respiratory rate, blood oxygen tension, season, nasal discharge character and breathing pattern suggest these clinical signs warrant simultaneous assessment. Notably, body condition score, sex and breed showed no relationship to mucus parameters, challenging assumptions that nutritional or demographic factors directly influence secretion presentation. For practitioners, these findings reinforce that elevated mucus quantity on endoscopy—particularly in symptomatic cases—warrants investigation for SEA and its underlying neutrophilic airway disease, though the absence of a truly healthy control group means caution is warranted when interpreting mucus scores in individual horses without supporting clinical context.
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Practical Takeaways
- •Elevated mucus quantity scoring on endoscopy is a useful diagnostic marker specifically for identifying horses with severe asthma; use it to inform clinical severity assessment and treatment intensity decisions
- •The correlation between mucus scores and neutrophilic airway inflammation supports the use of endoscopic evaluation as a non-invasive proxy for underlying airway cytological changes when bronchoalveolar lavage is not performed
- •Clinical signs like respiratory rate, nasal discharge character, and breathing pattern correlate with mucus parameters and can aid diagnosis, whereas body condition score alone does not predict mucus accumulation in asthmatic horses
Key Findings
- •Mucus quantity score >2 was associated with 3.6-fold increased odds of diagnosing severe equine asthma (p<0.001), but not mild to moderate asthma
- •Weak positive correlation found between neutrophil granulocytes in bronchoalveolar lavage fluid and mucus quantity score (rho: 0.353, p<0.001) and mucus viscosity score (rho: 0.225, p<0.001)
- •Mucus scores were significantly associated with age, respiratory rate, arterial oxygen partial pressure, season, nasal discharge type, and respiratory pattern (p<0.001), but not with body condition score, sex, or breed