Incomplete ossification of the tarsal bones in foals: 22 cases (1988-1996).

The research investigates the outcomes of foals with incomplete ossification of the tarsal bones and whether initial clinical and radiographic abnormalities influence these outcomes. It concludes that the severity of the radiographic findings is associated with outcome and foals with Type-II ossification, characterized by more than 30% bone collapse and associated pinching or fragmentation, are less likely to achieve athletic soundness.

Research Context and Methodology

• This study focuses on foals with a condition called incomplete ossification of the tarsal bones. Ossification is the process of bone formation, so ‘incomplete ossification’ means that the bone has not fully formed.
• It investigates whether there is a link between the severity of clinical and radiographic abnormalities seen in initial examinations, and the outcome for these foals. The aim is to understand the prognosis and possible future performance abilities of the affected foals.
• The research method is retrospective, studying past cases: a total of 22 foals are examined in the study. Information has been gathered from medical records, including animal details, history, owner’s initial complaint, and clinical findings, coupled with whether tarsus valgus (a deformity in which there is a lateral deviation of the bone) was obvious, and the details of any radiographic abnormalities.
• Radiographic abnormalities are classified into two categories: type I (with incomplete ossification and less than 30% collapse of the affected bones) and type II (incomplete ossification with over 30% bone collapse, accompanied by pinching or fragmentation of these bones).

Results of the Research

• Foals involved in the study were between 1 day and 10 months old at initial examination. Of these, eleven were premature or twins.
• A large majority of the foals (sixteen out of twenty-two) had tarsus valgus.
• The findings indicate that the severity of radiographic lesions was linked to the outcome for the foals. Four out of six foals with type-I incomplete ossification of the tarsal bones performed as expected, while only three out of sixteen foals with type-II incomplete ossification of the tarsal bones achieved the same success.

Conclusions Drawn From the Study

• For foals with incomplete ossification of the tarsal bones, the severity of the radiographic lesions was associated with the outcome. The more severe the observed abnormalities on radiography, the poorer the prognosis for the foal’s future performance.
• The prognosis for athletic soundness in foals with type-II incomplete ossification of the tarsal bones is guarded, indicating that these foals may struggle to achieve athletic soundness due to the extent of their bone abnormalities.