Owner-reported coughing and nasal discharge are associated with clinical findings, arterial oxygen tension, mucus score and bronchoprovocation in horses with recurrent airway obstruction in a field setting.
Authors: Rettmer H, Hoffman A M, Lanz S, Oertly M, Gerber V
Journal: Equine veterinary journal
Summary
# Editorial Summary This 2015 Swiss study examined whether owner observations—specifically reports of coughing frequency and nasal discharge—correlate with objective clinical and laboratory findings in 34 RAO-affected horses compared to 28 healthy controls under normal field conditions. Researchers used a comprehensive diagnostic approach including clinical examination, arterial blood gas analysis, endoscopic assessment of mucus accumulation, cytological analysis of airway secretions, and histamine bronchoprovocation testing via plethysmography. Frequently coughing horses showed the most pronounced differences from healthy animals, and histamine responsiveness clearly differentiated healthy horses from all RAO groups; however, mucus grades and neutrophil percentages in both tracheobronchial secretions and bronchoalveolar lavage fluid demonstrated substantial overlap between groups. Critically, the absence of owner-reported coughing and nasal discharge failed to exclude significant neutrophilic airway inflammation, and owner satisfaction with clinical status proved unreliable as an indicator of disease severity. For equine professionals, this research demonstrates that whilst owner reports of coughing provide useful baseline information for RAO monitoring in field settings, they cannot be used in isolation to assess disease severity or rule out active airway inflammation; objective testing such as bronchoprovocation remains essential for reliable clinical decision-making, particularly in apparently asymptomatic RAO-affected horses.
Read the full abstract on PubMed
Practical Takeaways
- •Owner reports of coughing and nasal discharge provide clinically useful information for assessing RAO severity in field settings, but cannot be relied upon alone to rule out airway disease
- •Do not assume an asymptomatic RAO horse has resolved airway inflammation—airway hyperresponsiveness testing reveals disease in horses with minimal clinical signs
- •Owner satisfaction is a poor indicator of actual disease severity; pursue objective clinical and diagnostic measures to guide treatment decisions rather than relying on subjective owner assessments
Key Findings
- •Owner-reported coughing frequency and nasal discharge are associated with clinical findings, arterial oxygen tension, mucus scores, and bronchoprovocation responses in RAO-affected horses
- •Frequently coughing horses showed the most marked differences from healthy controls, with significant differences in histamine bronchoprovocation parameters across all RAO groups
- •Mucus grades and neutrophil percentages in tracheobronchial and bronchoalveolar lavage fluid showed high variability with substantial overlap between groups
- •Absence of coughing and nasal discharge does not rule out significant neutrophilic airway inflammation, and high owner satisfaction was reported even in severely affected horses