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.

The research expands on horse owners reporting symptoms of their RAO (Recurrent Airway Obstruction) affected animals and its relation to clinical findings such as arterial oxygen tension, mucus score, and bronchoprovocation. RAO is a chronic, noninfectious airway condition in horses that is clearly identified with specific clinical and diagnostic findings. These findings suggest owner-reported symptoms can provide insight, but they should not replace clinical examinations.

Research Methodology

• The researchers conducted a cross-sectional study involving 28 healthy and 34 RAO-affected Swiss Warmblood horses. The horses were grouped based on the owners’ reports of ‘coughing frequency’ and ‘nasal discharge’.
• Horses in these groups were then observed and compared through various clinical examinations, including blood gas analyses, endoscopic mucus scores, and cytology of tracheobronchial secretion.
• The study also employed airway hyperresponsiveness tests using plethysmography with histamine bronchoprovocation. This procedure helps in identifying the responsiveness of the airways in horses.

Key Findings

• The study found that horses that cough frequently differed significantly from the healthy control group.
• Parameters derived from histamine bronchoprovocation were significantly different between the healthy control group and all the RAO groups, implying that the condition notably impacts the horse’s respiratory health.
• The mucus grades and tracheobronchial secretion and bronchoalveolar lavage fluid neutrophil percentages observed showed high variability, leading to overlap of findings between the groups. This signifies that while these may provide some indication of RAO, they are not definitive markers.
• Despite the severity of the condition in some horses, most owners expressed high satisfaction with the clinical status of their horses. This suggests a disconnection between the owner’s perception of an RAO-affected horse’s health and the clinical findings.

Conclusions

• The study confirms that owner-reported coughing and nasal discharge symptoms can be associated with specific clinical and diagnostic findings in RAO-affected horses in field settings.
• However, the absence of coughing and nasal discharge does not exclude significant neutrophilic airway inflammation, an indicator of RAO.
• The research emphasises the importance of regular clinical examinations for horses and suggests that owner-reported symptoms should complement, not replace, these diagnostic procedures.