Detection of an epidermoid cyst in the foot of a horse by use of magnetic resonance imaging.

This research article addresses a case of a horse with a moderate forelimb lameness, undetectable by palpation or traditional imaging techniques. The use of magnetic resonance (MR) imaging revealed a soft tissue mass in the foot of the horse which was treated successfully with local anesthetic and surgery, underlining the importance of MR imaging when conventional diagnostic methods fail.

Case Description

• The subject of the study was a 4-year-old Quarter Horse stallion with a 10-month history of moderate left forelimb lameness, noticeable when the horse was trotting over a smooth, hard surface.
• Preliminary evaluations such as palpation and hoof testers didn’t reveal any abnormalities in the horse’s forelimbs. However, lameness was eradicated following the administration of a palmar digital nerve block in the left forelimb.

Clinical Findings

• Conventional imaging techniques, such as radiography and ultrasonography, failed to identify any abnormalities in the horse’s left forelimb foot.
• MR imaging proved to be effective in accurately detecting the problem: a soft tissue mass in the distal aspect of the digital flexor tendon sheath (DFTS), situated above the lateral part of the deep digital flexor tendon.
• Injection of the left forelimb DFTS with local anesthetic resulted in a 90% improvement in the horse’s lameness.

Treatment and Outcome

• The horse’s DFTS was evaluated using tenoscopy, and the identified mass was surgically removed under tenoscopic guidance.
• Post-surgery, the horse was put on 10 days of oral phenylbutazone, and received an injection of hyaluronic acid and methylprednisolone acetate in the left forelimb DFTS after a week.
• Following a rehabilitation program, the horse was able to return to full training at six months post-surgery and competed successfully in events over a two-year follow-up period.

Clinical Relevance

• The use of MR imaging in veterinary medicine proved crucial when a definitive diagnosis wasn’t obtainable through traditional imaging techniques like radiography or ultrasonography.
• Specifically for lame horses, MR imaging can help accurately localize and diagnose any issues, especially when the root of the lameness has been narrowed down to a specific anatomical region through the use of diagnostic anesthesia.