Cardiac Disease Causes Poor PerformanceBy Kentucky Equine Research Staff · February 8, 2010
An article in Hoof Beats indicates cardiac disease is the third most significant cause of poor performance in horses, following problems with the respiratory or musculoskeletal systems.
While it is estimated that more than 60% of Standardbreds have leaky heart valves that allow some blood to flow backward with each contraction, this condition is rarely severe enough to cause a drop in performance. Heart murmurs are also fairly common in many breeds but generally do not impact performance.
Severe structural defects of the heart are rare, although irregular heartbeat patterns are somewhat more common in horses than in other domestic species. Aortic aneurysms (weak or bulging spots in the wall of a major artery) usually are undetected until they burst. When a performance horse collapses and dies during a race or other stressful event, the cause is frequently spoken of as a heart attack, but is more likely to have been a burst aneurysm than the type of heart attack that is seen in humans.
