SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
Managing Exercise-Induced Pulmonary Hemorrhage ( EIPH )
Warwick M . Bayly BVSc , MS , PhD , Dip ACVIM College of Veterinary Medicine , Washington State University , Pullman WA
EIPH is ubiquitous in Thoroughbred racehorses and also occurs following other types of strenuous exercise like polo and barrel racing as well as Standardbred and Quarter Horse racing .
Furosemide Globally , furosemide ( F ) is the drug most commonly used to attenuate the severity of EIPH , regardless of whether its use is permitted on the day of competition or not . Most episodes of EIPH do not appear to be associated with reduced performance although the slightest evidence of EIPH is used to justify treatment with F in countries where pre-race administration of the drug in legal .
It is unclear as to the extent of F use during training of racehorses , particularly when its use on raceday is prohibited . While reports are anecdotal , F use is apparently widespread globally in this context , with the frequency of use being highly varied . Many European and Australian TB trainers routinely use F prior to a hard work ( aka “ breeze ”). Little is known about the effects of repeated administration of F under these conditions , although it has been associated with the loss of skeletal calcium in people . There is also good evidence that the increased urinary excretion of calcium persists for > 24 hrs , which is well after the diuresis associated with F has gone and the drug itself has been almost completely metabolized .
F reduces the severity of EIPH , particularly the more severe episodes ( Grades 3 and 4 ), and horses ’ performances are improved following administration of F ~ 4h beforehand . The mechanism by which F achieves these effects has not been clearly demonstrated although the reduced severity of EIPH is usually attributed to decreased pulmonary arterial pressure although this does not make sound physiological sense . Other potentially important extrarenal effects of F have been studied in other species but not horses ( eg , effects on pulmonary venous pressure and capacitance and left atrial pressure during high speed exercise ).
Personal observation indicates that many horsemen and some veterinarians are unsure of why they are using F to manage EIPH . There is widespread belief that F prevents EIPH rather than attenuates it and that its administration helps performance . It is not uncommon for people with large numbers of horses receiving F before strenuous exercise to believe they have no “ bleeders ” although they are all getting F . However , if these horses are competing well , no diagnostic test ( s ) for EIPH have been performed . If they had , it is likely that there would be signs of EIPH , especially on bronchoalveolar lavage .
A minority of horses develop debilitating pulmonary pathologies like pulmonary venoocclusive disease and pulmonary fibrosis secondary to the repeated presence
70