INCOMPLETE OSSIFICATION OF THE TARSAL BONES IN FOALS - 22 CASES (1988-1996)

Objective-To determine outcome for foals with incomplete ossification of the tarsal bones and to determine whether clinical and radiographic abnormalities at the time of initial examination were associated with outcome. Design-Retrospective study. Animals-22 foals. Procedure-Info rmation on signalment, history, owner's initial complaint, clinical fi ndings, whether tarsus valgus was evident, and radiographic abnormalit ies was obtained from medical records. Radiographic lesions were class ified as type I (ie, incomplete ossification with < 30% collapse of th e affected bones) or type II (incomplete ossification with > 30% colla pse and pinching or fragmentation of the affected bones). Follow-up in formation was obtained via telephone conversations with owners. Result s-Foals were between 1 day and 10 months old when first examined. Elev en were premature (ie, < 320 days of gestation) or were twins. Sixteen had tarsus valgus. Severity of radiographic lesions was associated wi th outcome; 4 of 6 foals with type-1 incomplete ossification of the ta rsal bones performed as intended, but only 3 of 16 foals with type-ii incomplete ossification of the tarsal bones performed as intended. Cli nical Implications-For foals with incomplete ossification of the tarsa l bones, severity of the radiographic lesions was associated with outc ome. Foals with type-it incomplete ossification of the tarsal bones ha ve a guarded prognosis for athletic soundness.