| Abstract: | Horses experience greater fatigue lameness and bone fracture-breakdown at certain race distances. It is predicted that lameness would be reduced about 14% and bonefracture-breakdown about 24% if these distances were eliminated.It is generally believed but inadequately documented, and difficult to prove, that fatigue is a significant factor among the causes of lameness in horses, particularly horses working at speed. In a previous report (1) preliminary data were presented on 94 races which suggested that the fatigue experienced by Thoroughbred racehorses was, in part, a function of the length of the race. In this report a larger number of races have been examined, and the frequency of bone fracture in relation to race length has been examined.From the Past Performances of several issues of The Racing Form, 234 races were taken by chance for analysis. No attempt was made to sort the races by track, quality, age of starters, etc. Races at tracks from all major racing areas in the United States were included.The fractional times given in the Past Performances were used to calculate the velocity of the horse in the lead for each segment of the race. The velocities, then, are population velocities for the population of horses in the race and not for individual horses. From this data the drop in velocity was calculated from one segment of the race to the next. All the data are presented as the mean and standard deviation of the total number of races examined and are in feet/second.In order to have some comparison of the population data with individual horse performance, two horses were selected, and their segment velocities and velocity drops calculated for races at different distances.Data were available from one racing venue for determination of the frequency of lameness in relation to race length. This data consisted of the horses coming out of a race lame enough to be assigned to the “vet's list.” There were 2006 races and 443 horses placed on the vet's list during one 12 month period. There were 2036 races and 407 horses listed during the next 12 month period. Data from a second racing venue were available for one 12 month period and consisted of horses which fractured a bone in a race. |
