INFLUENCE OF RADIOGRAPHICALLY DETECTABLE ORTHOPEDIC CHANGES ON RACINGPERFORMANCE IN STANDARD-BRED TROTTERS

The tarsocrural, metacarpophalangeal, and metatarsophalangeal joints o f 753 Standardbred yearlings were radiographed. On the basis of radiog raphic findings, the horses were allotted into 4 groups. Group-1 horse s had osteochondrosis in the tarsocrural joints. Group-2 horses had pa lmar/plantar bony fragments in the metacarpo- and metatarsophalangeal joints. Group-3 horses had radiographic changes in the metacarpo- and metatarsophalangeal joint region, such Its bony fragments located at t he dorsoproximal end of the proximal phalanx, osteochondrosis of the s agittal ridge of the third metacarpus/metatarsus, ununited proximoplan tar tuberosity of the proximal phalanx, or nonarticular, osteolytic an d productive changes in the proximal sesamoid bones. Group-4 hones did not have radio,ovaphic changes. The number of race starts and race ea rnings (categorized) of the horses in groups 1, 2, and 3 were compared with those of the horses in group 4, using a multivariate regression analysis. Horses in groups 1, 2, and 3 had significantly fewer starts and somewhat lower earnings compared with the horses in group 4.