Concurrent multi-systemic eosinophilic epitheliotropic disease and choledocholithiasis in a 15-year-old mixed-breed mare.

A mixed-breed 15-year-old mare was euthanized for recurrent colic, severe weight loss, pastern ulcerative dermatitis, and coronitis without response to non-surgical medical procedures. The liver was congested with firm consistency at necropsy, and there were multi-focal white spots on Glisson's capsule. Hemorrhage, ulcer, severe folding, and hypertrophy were seen in the duodenum and jejunum. Histopathological examination showed marked infiltration of eosinophils concomitant with fewer leukocytes, macrophages, and plasma cells, primarily in the liver and intestines. The presence of eight calcium bilirubinate stones, 2.00 - 5.00 cm in diameter, in the common bile duct was characteristic of choledocholithiasis. Concurrent multi-systemic eosinophilic epitheliotropic disease (MEED) and choledocholithiasis were confirmed after ruling out other potential causes of eosinophilic infiltration, including parasitic infection and allergy. The cause of MEED and choledocholithiasis was unclear because of incomplete case history and delayed referral, with a potential infection playing a role and having synergistic effects between the two conditions. When eosinophilic-associated inflammation involves several organs, MEED should be on the differential diagnostic list since infections and allergens are also among the risk factors for this disorder.