2017 ACVIM Forum Research Abstract Program

This study shows EIPH is present in barrel racing horses in the Pacific Northwest and may impact performance. The long term effects of EIPH and other variables requires further study. Cardiac arrhythmias, most notably atrial fibrillation, have been linked to poor performance. In a recent study Draft and Warmblood breeds were more likely to be presented with atrial fibrillation in comparison to most light breeds, with the exception of Standardbreds. To our knowledge there is no data describing a population of competition ready Draft horses. Our objective was to determine the prevalence of silent cardiac arrhythmias in a population of Draft horses. A convenience sample of 245 Draft horses was studied at the 2015 Michigan Great Lakes International Draft Horse Show. Information gathered on each horse included signalment, history of poor performance, upper airway noise, myopathy, and cardiac arrhythmias or murmurs. All horses were auscultated on each side of the thorax for 30 seconds. A 30-second electrocardiographic (ECG) recording was then taken using a handheld recording device that transmitted to a smart phone (AliveCor Ã’ ). ECG recordings were evaluated for rhythm and heart rate, P-R interval, and R-R interval were measured. The study population included 82 Percherons, 69 Belgians, 69 Clydesdales, 11 Belgian mules, 8 Shires, and 5 Percheron mules. Arrhythmias were found in four horses: atrial fibrillation (1), ventricular premature depolarizations (1), second degree atrioventricular block (2). None of these horses had a history of poor performance or known cardiac arrhythmias. We concluded that the prevalence of silent arrhythmias in well-conditioned, competitive Draft horses is low (2/245; 0.8%).