Objective To determine clinical, clinicopathologic, radiographic, ultrasonographic, and coagulation abnormalities in dogs in which acute pancreatitis was fatal. Design Retrospective study. Animals 70 dogs. Procedure History, clinical signs, and physical examination findings at the time of initial evaluation at the veterinary teaching hospital; results of pretreatment laboratory tests, abdominal radiography, and ultrasonography; and histologic abnormalities were obtained from medical records. Results Clinical signs included anorexia, vomiting, weakness, diarrhea, polyuria and polydipsia, neurologic abnormalities, melena, weight loss, hematemesis, and passage of frank blood in feces. At the time of initial examination at the veterinary teaching hospital, 68 (97%) dogs were dehydrated, 18 (26%) were icteric, 22 (32%) were febrile, 40 (58%) had signs of abdominal pain, and 30 (43%) were classified as overweight or obese. Most dogs had leukocytosis, neutrophilia with a left shift, and thrombocytopenia. Various serum biochemical abnormalities were identified, including hypoglycemia, azotemia, hypercalcemia and other electrolyte abnormalities, hypoalbuminemia, high hepatic and pancreatic enzyme activities, hypercholesterolemia, and lipemia. For 17 of 28 (61 %) dogs, results of coagulation function tests were abnormal. Results of abdominal ultrasonography and radiography were consistent with a diagnosis of acute pancreatitis in 23 of 34 (68%) and 10 of 41 (24%) dogs, respectively. For 2 dogs, results of abdominal ultrasonography were not suggestive of acute pancreatitis, but results of abdominal radiography were. Clinical Implications Clinical signs and results of clinicopathologic tests are inconsistent. Abdominal ultrasonography may be valuable in the diagnostic evaluation of dogs suspected to have acute pancreatitis. (J Am Vet Med Assoc 1998;213:665-670)