Electrocardiography, heart scope and haematology of horses competing in an endurance ride.

Thirty-one horses competing in a 100 kilometre endurance ride had electrocardiograms recorded before and after the ride from which the heart score of each horse was calculated. Blood was also taken to determine the packed cell volume (PCV) and total plasma protein (TPP) before the ride, after 60 kilometres (mid ride) and at completion of the ride. Statistical analysis of the heart scores showed that a faster group of horses had significantly higher heart scores than either a slower group or those eliminated due to inadequate recovery of heart rate. No horses developed electrocardiogram abnormalities as a result of the ride. Analysis of the results of PCV and TPP showed that horses became dehydrated during the ride. The faster group of horses had significantly higher PCV values and heart rates at both the mid-ride and end of ride sampling times. However, the TPP values indicated no significant differences in the amount of dehydration between the 2 groups.