An animal model for studying endoscopic ultrasound changes of early chronic pancreatitis with histologic correlation: A pilot study

Background and study aims: Due to the difficulty in obtaining pancreatic tissue for histology in humans, we developed an animal model for studying endoscopic ultrasound (EUS) changes of early chronic pancreatitis. This report on the animal model describes the serial changes of early chronic pancreatitis by EUS and correlates results with histology. Materials and methods: Four 60-80-lb dogs were used in the study. Pancreatic EUS was performed to provide baseline images prior to any procedure. At laparotomy, a guide wire was passed into the pancreatic duct, and a 5-Fr pancreatic stent was introduced over the wire into the pancreatic duct. Animals were divided into two survival groups - 2 weeks and 4 weeks. In each group, EUS examination was performed under anesthesia to image the pancreas and then followed by euthanasia. Sequential pancreatic sections were taken from the head, body, and tail of the pancreas. EUS findings were correlated with histologic results with respect to degree of fibrosis, inflammation, and edema. Results: At baseline EUS, the pancreas appeared homogeneous with only a few echogenic septations and echogenic margins of the main pancreatic duct. At 2 and 4 weeks poststenting, EUS images showed the following changes: lobularity, hyper and hypoechoic foci, increased echogenic septations, visible pancreatic duct side branches, and irregular margins of the main pancreatic duct. Conclusions: The dog model for chronic pancreatitis appears to be a promising method for studying sequential changes of chronic pancreatitis by EUS and correlating results with histology.