Recurrent esophageal obstruction and dysphagia due to a brainstem melanoma in a horse.

A 13-year-old Arabian mare was examined and treated for recurrent esophageal obstruction and dysphagia, which was later found to be caused by a brainstem melanoma.

Initial Presentation

• The horse was initially presented with nasal discharge and weight loss. It also previously had an episode of esophageal obstruction which resolved on its own and mucopurulent nasal discharge that temporarily resolved with antimicrobial therapy.
• Physical examination found bilateral mucopurulent nasal discharge, increased lung and tracheal sounds, moderate dental enamel points and two black cutaneous masses. A CBC and serum biochemistry test showed hyperfibrinogenemia and mild hyperglobulinemia.
• Thoracic radiographs revealed issues with the ventral lung fields and gaseous esophageal distention.

Treatment

• Treatment included antimicrobials, lactated Ringer solution, and nonsteroidal anti-inflammatory drugs. Endoscopy confirmed an esophageal obstruction from feed material, which was removed under general anesthesia. The horse was discharged with continued antimicrobial therapy instructions.

Subsequent Visits

• The horse was returned to the hospital a month later, with symptoms including nasal discharge containing feed particles, dehydration, and respiratory difficulty. Tests showed leukopenia, high hematocrit, hypochloremia, and hyperglobulinemia. Consequently, the horse was treated with nasal insufflation of oxygen.
• A second endoscopic examination identified esophageal obstruction, inflamed and edematous pharynx, and left laryngeal hemiplegia. Thoracic radiographic evaluation continued to be consistent with ventral consolidation.
• After repeated esophageal obstructions, further diagnostics were conducted to determine the cause. Diagnostics did not find TMJ pain, dental abnormalities, oral pain due to foreign bodies, hyoid apparatus injury, abnormal esophageal anatomy including strictures or diverticula. Abnormalities in cranial and TMJ regions were not observed in radiographic evidence. However, palpation elicited some evidence of pain at the right TMJ. Sharp enamel points and a caudal hook on the left mandibular 3rd molar were removed.
• The esophagram did not show strictures, diverticula, or other abnormalities and neurologic examination was unremarkable except for limited masticatory excursion. Only after her condition did not improve did they find the cause of her condition was an undiagnosed brainstem melanoma.