Diagnostic Methods for EIPH: Field Vs. Lab

Exercise-induced pulmonary haemorrhage (EIPH) is a common problem affecting the lower airways of racehorses¹. The cost of EIPH to the Thoroughbred and Standardbred racing industries in the United States is estimated to be $115,000,000 - $225,000,000 annually, not including the cost of racing and training days missed and the shortened racing career of affected horses². Multiple techniques are available for determining the occurrence of a previous episode of EIPH, including visualisation of epistaxis, trache-obronchic endoscopy or cytological investigation of either tracheal wash (TW) or broncho-alveolar lavage fluid (BALF) for detection/quantification of red blood cells (RBC) or hemosiderophages. The utility of these diagnostic tests, and then the methodological choice, mainly depends on the time between racing and the examination as well as the required sensitivity of the employed test. Tracheobronchoscopy is indeed most appropriate within 30 min – 2h post-exercise. Cytology of respiratory fluids is a more sensitive method, since previous episodes of haemorrhage might be detected up to several weeks later. Radiography, scintigraphy and pulmonary function tests, while useful for other respiratory conditions, are largely of minimal relevance in confirming a diagnosis of EIPH or in determining its severity. Above all, it is worth mentioning that EIPH is very common in racehorse and should be considered the cause of poor performance only after other causes have been eliminated³. The prevalence of EIPH varies with the diagnostic methods being used, and the frequency with which horses are examined. In the Thoroughbred population indeed, the reported prevalence for a single investigation ranges 43.8–75.4%4,5. It is also clear that increased frequency of examination will lead to an increased prevalence. Thus, for a single examination, around 40-60% of hors- es examined may have blood in the trachea following racing, while the prevalence will reach about 100% when horses are examined on 3 separate occasions⁶. […]