Cholangiocarcinoma in a female horse

Introduction Bile duct carcinoma has been reported in many species, but there have been only few reports in horses. Cholangiocarcinoma is the most common primary hepatic neoplasm in the horse.We report a case of hepatic neoplasm in a horse. Case report A 20 years old warmblood mare was presented with anorexia and a 4 week history of weight loss despite feeding ad libitum. Before the referral, the horse had not been treated. On physical examination the subject was quite and responsive, but in poor body condition (BCS 2). All the other physical parameters were within normal range except for a mild icterus. A complete CBC count, biochemical and coagulation profiles were carried out. Haematology revealed mild neutrophylic leucocytosis (10.7 K/ml, reference range 5-9 K/ml). Biochemistry showed an increase in total plasma proteins (74 gr/L, 50 to 60.4 gr/L) [4], increased total plasma bilirubin (3.79 mg/dl, 0.5-2.3 mg/dl) [1], unconjugated (3.1 mg/dl, 0.2-2 mg/dl) [1] and conjugated (0.7 mg/dl, 0-0.6 mg/dl) (1) bilirubin. The horse showed also hypoglicemia (83 mg/dl, 89-112 mg/dl) (1) and an increase in serum activities of gamma-glutamyltransferase (GGT) (197 U/L, 8-22 U/L) and aminoaspartatetransferase (AST) (746 U/L, 138-409 U/L). BUN was increased (35 mg/dl, 12-27 mg/dl), while ammonia and plasma creatinine were within normal ranges. Coagulation profile was normal. Transabdominal ultrasoography revealed multiple roughly circular ipo- and hyperechoic areas (2-6 cm) within the hepatic parenchyma. No peritoneal effusion was found. Ultrasound-guided fine needle aspiration revealed clusters with tubular and acinar cytoarchitecture; cells presented a high cytoplasm/nucleus ratio, nuclear pleomorphysm and some mitosis. Hepatocytes with irregular cytoplasmic vacuolization were found. Cytological findings suggested duct epithelial neoplasia. The owner decided not to treat the mare. The subject died at home after 3 weeks and the post-mortem examination was not performed, according to the owner’s will. Discussion and conclusion The hematological alterations could be related to the inflammatory status of horse. The biochemical findings were suggestive of both hepatocellular (increased AST) and biliary (increased GGT) damage. GGT is the most sensitive biochemical indicator of hepatopathy, and marked increases in serum GGT activity are associated with a poor prognosis. Although AST has low specificity for liver disease, most liver disease cases have increased serum AST. The slightly increased total plasma, unconjugated and conjugated bilirubin concentrations may have been related to liver dysfunction, but they were more likely due to the horse’s inappetence as hypoglycemia, an uncommon consequence of hepatic failure. The neoplasm itself could have been responsible for impaired liver function, and together with possible malabsorption, for the weight loss.