“Avery,” a 12-year-old Suffolk Punch gelding used for trail riding, was referred to the Virginia-Maryland College of Veterinary Medicine (VMCVM) Large Animal Teaching Hospital on June 27, 2018, for further evaluation of a suspected keratoma. Avery had a history of reoccurring sub-solar abscesses and rapidly-progressive lameness on his right thoracic hoof.

Under physical examination, Avery presented with a 4/5 (American Association of Equine Practitioners grading scale) lameness on his right thoracic limb. He had an increased digital pulse in this foot, while all other digital pulses were within normal limits. Avery was negative to hoof testers in all limbs, except for the affected limb. He had a distinct defect as well as multiple draining tracts in his sole and around the defect of the affected hoof. Paring out this area revealed grey, odoriferous exudate (Figure 1). A palmar digital nerve block was preformed to facilitate probing of the tract.

Following the initial examination, radiographs were obtained. Radiographic examination of the right thoracic hoof and distal phalanx included 0° lateral-medial, 0° dorsopalmar, 65° proximodorsal-palmarodistal oblique, dorsal 65° proximal 45° lateral-palmaromedial oblique, and dorsal 65° proximal 45° medial-palmarolateral oblique. A dorsopalmar 65° oblique radiograph of the left thoracic distal phalanx…