Diagnostic exercise: intraosseous epidermoid cysts in the third phalanx of a dressage mare.

This research article examines a case where an 11-year-old Dressage mare presented abnormal gait. Upon inspection, two intraosseous epidermoid cysts were discovered in the third phalanx of the horse’s hoof, confirmed through radiographic, computerized tomographic evaluations, and histologic and histochemical results.

Background of the Study

• The horse was a dressage mare aged 11 years.
• The horse was brought in due to an abnormal gait, triggering concern from the handlers.
• The initial hypothesis was that the horse had an abscess in the left hoof, but this wasn’t evident upon observation.

Diagnostic Procedures and Findings

• Radiographic (X-ray) and computerized tomographic (CT) evaluations were carried out on the horse to get a clear understanding of the issue.
• These evaluations revealed a large cystic lesion located near the apex (the tip) of the pedal bone (the bone within the hoof).
• Additionally, a smaller lesion of similar characteristics was present at the lateral wing (side) of the same bone.
• To further investigate, sagittal sections (cuts made along the length of the bone) were performed, confirming the presence of two intraosseous cysts (cysts within the bone) at the third phalanx (the bone at the very end of the hoof).

Confirmation of the Diagnosis

• Aside from the radiographic and tomographic evaluations, histologic and histochemical analyses of the cysts were conducted.
• These histologic and histochemical results characterized the lesions as intraosseous epidermoid cysts.
• Epidermoid cysts are benign (noncancerous) growths that often arise from the epidermis, or the outer layer of skin. In this case, they developed within the bone of the hoof.
• The identification of these cysts allowed for a more accurate diagnosis beyond the initially suspected abscess.

Implications of the Findings

• This research provides insight into diagnostic interventions and treatments for similar cases in equine medicine.
• It breaks down the diagnostic process, revealing the importance of comprehensive evaluation methods in accurately identifying the inherently diverse set of possible hoof-ailment causes.