Equid herpesvirus 2-associated oral and esophageal ulceration in a foal.

A case of a 1-month-old Thoroughbred foal with dysphagia, salivation, pyrexia, oral mucosal pustules, and esophageal ulceration is reported. Swabs from the ulcerated lesions yielded Equid herpesvirus 2 (EHV-2) in virus isolation assays, and histopathology of a biopsy from the esophageal lesion identified nuclear inclusions suggestive of herpesviruses. Immunohistochemical staining with antibodies specific for EHV-2 was positive for epithelial cells in the vicinity of the ulcer but not in more distant mucosa. Electron microscopic evaluation of the biopsy showed herpesviral particles in epithelial cells. The foal recovered over 5 days of supportive and gastroprotective therapy, and the esophageal ulcers healed. Serology and immunohistochemistry indicated that this foal likely had lesions associated with EHV-2 and not EHV-1, -4, or -5.