Signal changes in standing magnetic resonance imaging of septic pedal osteitis in a thoroughbred racehorse

Septic pedal osteitis refers to bacterial infection within the distal phalanx, which requires effective surgical intervention. A 3-year-old Thoroughbred colt underwent standing magnetic resonance imaging (sMRI) on the 10th day after admission (day 10), which revealed hyperintensity beneath the inner hoof wall in sagittal T2*-weighted and transverse T2-weighted sequence, suggesting abscess formation. On day 25, the second sMRI indicated development of osteitis, in which the lesion extended into the distal phalanx. This lesion was imaged as hyperintensity on T1-weighted, T2*-weighted and T2-weighted images. On day 59, laminitic changes were evident on T1-weighted and T2*-weighted images. Our case report suggests that sMRI could allow better understanding of the disease process than other conventional imaging modalities, and guide early surgical intervention.