A 10 year old Thoroughbred gelding was presented to the Large Animal Internal Medicine Service with the complaints of weight loss and episodes of mild colic of one month’s duration. Previous to this, the horse had the skin on the white areas of the hair coat (muzzle and left hind leg) slough after exposure to sunlight. At this time elevated liver enzymes were detected by the referring veterinarian and the horse was diagnosed with photosensitization and suspected hepatopathy.

On presentation physical exam revealed a poor body condition (BCS 3/9), quiet demeanor, icteric sclera and mucous membranes, and dermatitis of the white areas of skin. Cytology of a skin scraping revealed bacteria, and a secondary staphylococcal dermatitis was confirmed on culture. Elevated liver enzymes representative of hepatocellular injury (SDH, GLDH) and cholestasis (GGT), elevated total bilirubin, and an inflammatory leukogram were noted on bloodwork. The liver was homogenous in appearance on ultrasound but had a similar echogenicity to the spleen. A biopsy was taken of the liver and histopathology showed neutrophilic and lymphoplasmacytic infiltrates, biliary hyperplasia, and portal to portal bridging fibrosis, confirming a cholangiohepatitis. Culture of the liver tissue grew an E. coli that was sensitive to enrofloxacin. A gastroscopy revealed grade 3 out of 4 bleeding squamous gastric ulcers along the margo plicatus at the greater and lesser curvatures. The horse was prescribed enrofloxacin for the cholangiohepatitis, omeprazole for the gastric ulceration, and topical cleaning of the skin lesions.

Cholangiohepatitis is defined as inflammation of the biliary tree and liver and is a relatively uncommon condition in horses. Horses may become infected via either the biliary or portal systems with organisms commonly found within the gastrointestinal tract. Classic signs include intermittent fever and colic, depression, icterus, and weight loss. Secondary photosensitization and hepatoencephalopathy may also be seen. Diagnosis involves a combination of bloodwork, ultrasound examination, and biopsy, though these diagnostics may not be sensitive in all cases. Treatment involves long term antibiotic therapy and dietary modifications. Prognosis is most tightly correlated with increases in ALP, severity of ultrasonographic changes, and severity of histopathologic changes.