RACING PERFORMANCE AFTER HEMICIRCUMFERENTIAL PERIOSTEAL TRANSECTION FOR ANGULAR LIMB DEFORMITIES IN THOROUGHBREDS - 199 CASES (1987-1989)

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 wit h 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 perc entage 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) aff ected 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, regard less 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 metac arpal/metatarsal HCPT had fewer 2-year-old starts (1.09 vs 2.19), but did not have a significantly different SPR or lower starting percentag e, compared with values for controls. Houses treated with distal radia l HCPT had lower starting percentage (48 vs 55%), fewer 2-year-old sta rts (1.22 vs 1.70), and lower SPR (32.53 vs 53.32), compared with thos e of controls. Horses treated with HCPT in 2 or move anatomic sites ti e, distal part of radius and metacarpal bones) had a lower starting pe rcentage (33 vs 53%), fewer 2-year-old (0.65 vs 2.74) and 3-year-old s tarts (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 tie, more performance measures differed from those of t heir siblings), compared with that in horses treated at the distal par t of the metacarpal/metatarsal bone III or radius.