Summary

Inflammatory airway disease (IAD) is an important and common cause of poor athletic performance in Australian racehorses. Other signs attributed to IAD include exercise-associated cough, increased airway mucopus, and delayed recovery after exercise. Disease prevalence has been reported between 22 and 50% of performance horses and up to 20% for horses used for pleasure riding. The primary method of diagnosis is by examination of bronchoalveolar lavage fluid (BALF) cytology, a procedure commonly performed. IAD is further sub-grouped based on the relative proportion of certain cell lines in the BALF. The most frequent form of IAD in our population is attributed to a relative increase in mast cells in BALF. There are several problems with this method of diagnosis. These include variable cytology in normal horses, an absence of cytological change in some horses with typical signs of IAD, and that the technique does not provide any functional information on the respiratory tract.

Open plethysmography is a novel technique recently adapted to horses that provides information on airway mechanics. The procedure when used in conjunction with BALF cytology would provide critical information that could be used to determine which horses truly require therapy and then to assess the response to therapy.

The project aims to correlate BALF cytology with baseline or histamine-induced changes in pulmonary mechanics. In horses with elevations in the percentage of BALF mast cells we will correlate the proportion of cell with pulmonary mechanics and the concentration of a specific chemical indicator of mast cell activation in BALF.

Program

Thoroughbred Horses

Research Organisation

Murdoch University

Objective Summary

Determine what cytological changes and inflammatory cell percentages, in particular mast cells, correlate to hyperreactive airways as determined by pulmonary function testing in this geographical location.
Correlate the bronchoalveolar lavage fluid cytological findings with pulmonary function testing in clinical cases of poor performance that undergo a respiratory evaluation.