Summary
Racing records of 199 Thoroughbred foals with angular limb deformities surgically treated by hemicircumferential periosteal transection and elevation (hcpt) from 1987 through 1989 (principals) were compared with records of their 1,017 siblings (controls) for starting status; 2-, 3-, and 4-year-old starts; earnings and earnings per start; and starts percentile ranking number (spr). Principals had a slightly lower percentage of horses starting a race (45 vs 55%), fewer 2-year-old starts (1.06 vs 1.72), and lower spr (33.49 vs 49.18), compared with those of controls (P < 0.05). Starting status was significantly (P < 0.05) affected by surgery and the horse's sex, but not by anatomic site treated. Fillies were 1.74 times less likely to start than were colts, regardless of surgery, whereas principal fillies were 2.63 times less likely to start than were control colts. Difference was not detected between principals and controls in 3- or 4-year-old starts; 2-, 3-, or 4-year-old earnings, or earnings per start. Horses treated with distal metacarpal/metatarsal hcpt had fewer 2-year-old starts (1.09 vs 2.19), but did not have a significantly different spr or lower starting percentage, compared with values for controls. Horses treated with distal radial hcpt had lower starting percentage (48 vs 55%), fewer 2-year-old starts (1.22 vs 1.70), and lower spr (32.53 vs 53.32), compared with those of controls. Horses treated with hcpt in 2 or more anatomic sites (ie, distal part of radius and metacarpal bones) had a lower starting percentage (33 vs 53%), fewer 2-year-old (0.65 vs 2.74) and 3-year-old starts (2.93 vs 4.76), and lower spr (23.20 vs 37.25) than had controls. Performance in horses treated with hcpt at 2 or more anatomic sites thus was worse (ie, more performance measures differed from those of their siblings), compared with that in horses treated at the distal part of the metacarpal/metatarsal bone III or radius.
