Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 1: Preparation and composition of HDS.

The research article discusses an improved method for diagnosing and researching equine respiratory disease, known as ‘heaves’, using nebulised hay dust suspensions (HDS). This method provides a more standardised experimental protocol and offers an in-depth analysis of the organic components causing the response.

Objective of the Study

• This research aimed to standardise experimental protocols for diagnosing and investigating ‘heaves’ in horses. Heaves is typically studied by exposing horses to dusty hay, the reactions to which depend on the hay’s organic dust content and composition.
• The researchers hypothesised that using a hay dust suspension (HDS) would lessen the variability of the reaction and allow further study of the organic dust components causing the response.

Methodology and Analysis

• Three Hay Dust Suspensions (HDS-1, HDS-2, and HDS-3) were created from dust particles collected from three batches of dusty hay. Predominantly, the particles were fungal spores.
• HDS-1 and HDS-3 were analysed for endotoxin, beta-D-glucan, and protein concentrations. They were also assessed for general protease activity and for enumeration and size distribution of particulates.
• The research identified the main protease activity as being attributable to a 28 kDa serine protease and to 85 kDa and 160 kDa metalloproteases.

Conclusions and Recommendations

• The researchers found that all components of HDS, both soluble and particulate, could be delivered to the lung using standard nebulisation techniques. This result highlights the possibility of a detailed HDS analysis.
• Using nebulised HDS for diagnosing and studying heaves has been shown to have significant advantages over traditional hay/straw challenge methods. These benefits come from the reduction in response variability and the ability to further investigate the organic components responsible for the equine response.