Ultrasonographic, Computed Tomographic, and Magnetic Resonance Imaging of the Normal Donkeys (Equus asinus) Digit

Abstract

The present study was designed to provide a descriptive imaging database of the anatomic features of the digit of normal donkeys using ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) as a means to improve diagnosis and clinical decision-making regarding digit lameness in donkeys. Ten healthy donkeys with sound limbs were assigned for US examination of the digit in each forelimb. In addition, five donkey’s forelimb digit cadavers were subjected for CT and MRI examination. The donkey's digit was divided into three regions: fetlock, pastern, and foot. For evaluation of the digit, longitudinal and transverse US images were obtained. In CT evaluation, three plans were taken: axial, sagittal, and coronal. Whereas, in MRI evaluation, two plans were taken: axial and sagittal with two sequences, T1 and proton density. All US, CT, and MRI images of the donkey's digit were labeled and serially interpret using correlated anatomic cross-sections and references. There was a full description and proper differentiation of the anatomical features of the digit bony (distal third of cannon bone [MCIII], proximal sesamoid bones, phalanges, navicular bone, and digital cushion) and soft tissue structures (superficial digital flexor tendon, deep digital flexor tendon, suspensory ligament, intersesamoidean ligament, straight distal sesamoidean ligament, common digital extensor tendon, annular ligament, and fetlock joint capsule) on US, CT, and MRI images. In conclusion, US, CT, and MRI provide a useful noninvasive method for evaluation of the digit and give a well-defined baseline reference images for the donkey's digit for educational, research, and radiologic purposes.