An accidental discovery of ductal adenocarcinoma of the pancreas in an adult horse with severe abdominal pain

A native pony, eight years old and male, was tentatively diagnosed with abdominal pain and treated immediately. Sequential hematological profiles revealed increased levels of aspartate aminotransferase (AST), alkaline phosphatase (ALP), and creatinine, as well as reduced albumin. After the pony's death, which occurred eight days after treatment began, a necropsy was performed. The liver's external surface showed small foci, but no gross lesion was observed in the pancreas, which was enlarged. Haematoxylin and eosin (H&E) staining of the liver showed multifocal inflammation in the hepatic parenchyma, coinciding with bile duct hyperplasia. The pancreas H&E staining showed well-differentiated tubular glands with normal pancreatic islet morphology. The pancreatic immunohistochemical staining was positive for pan-cytokeratin in the cytoplasm, except in the pancreatic islet cells. It also confirmed negative chymotrypsin staining of the pancreatic tissue, indicating simple and branching ductal structures instead of acinar cells. The pancreas's histopathology was consistent with ductal adenocarcinoma, a condition previously unreported in adult equids. This result suggests that pancreatic tumors should be considered an uncommon differential diagnosis for abdominal pain in adult equids.