Correlates between human lung injury after particle exposure and recurrent airway obstruction in the horse.

The research article discusses the correlation between human lung injury due to particle exposure and the recurrent airway obstruction observed in horses. It highlights the symptoms, effects and prevalence of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO) in horses subjected to consistent particulate matter exposure, drawing comparisons to human pathologies.

Overview of Human and Equine Respiratory Ailments

• Prolonged exposure to particulate matter for humans has been linked to reduced lung function, increased incidences of bronchitis and asthma, infection rates, bronchial hyperresponsiveness, and histological evidence of emphysema and fibrosis.
• Like humans, horses are frequently exposed to particles, particularly in stables, often in the form of mould spores, grain dust and plant debris. This exposure often results in respiratory issues in horses.
• Two typical respiratory conditions in horses associated with stabling are Inflammatory Airway Disease (IAD) and Recurrent Airway Obstruction (RAO).

Inflammatory Airway Disease (IAD)

• IAD is associated with symptoms like cough, reduced exercise tolerance, delayed recovery from exercise, and variable increase in respiratory secretions.
• In horses with IAD, pulmonary function tests have shown lower airway obstruction and increased airway reactivity.
• There is also an increased number of neutrophils, mast cells, and/or eosinophils detectable in bronchoalveolar lavage.
• IAD is commonly found in young racehorses during their first year of training, however, longitudinal studies indicate that the prevalence reduces in older horses, suggesting the condition often resolves naturally in younger horses.

Recurrent Airway Obstruction (RAO)

• RAO, previously termed Chronic Obstructive Pulmonary Disease (COPD), typically affects older horses.
• RAO is characterized by episodes of severe respiratory distress caused by lower airway obstruction, presenting with increased abdominal effort, frequent coughing, and a high amount of mucus secretions.
• The inflammation observed in RAO is severe, with a high presence of neutrophils.
• RAO can lead to varying degrees of irreversible airway obstruction and reversible narrowing. A term ‘heaves’ or ‘broken wind’ is used to describe mature horses with RAO.
• Hyperreactivity is always seen in horses suffering from RAO and may worsen upon exacerbation, thus requiring preventive treatment with inhaled or systemically administered corticosteroids.

The research article primarily focuses on understanding the shared responses in the respiratory tracts of humans and horses exposed to particulate matter, with emphasis on the pathological manifestations in horses. The detailed exploration of respiratory conditions in horses due to particle exposure could inform future research on related human respiratory diseases.