The aetiology of acute pancreatitis in dogs is rather obscure. Although experimental studies may reveal a number of causative factors, an aetiological diagnosis is rarely established in 'spontaneous' pancreatitis. The pathogenesis and pathophysiology are reviewed. Activated trypsin plays a leading role in the injury to the pancreas, the ischaemia of the tissues and the disseminated intravascular coagulation. Vomiting, abdominal pain and general malaise are prominent features in the externally perceptible symptoms. Examination of the blood is of importance both in establishing the diagnosis and in determining the course of the disease. Great caution is indicated in setting store by individual results of haematological studies. There is neither a biochemical nor a haematological method of estimation today, by which acute haemorrhagic necrotic pancreatitis can be shown to be present or ruled out with one hundred per cent certainty. Treatment of the disease is mainly symptomatic. Complete withdrawal of food and water is the most important factor. Intravenous fluid therapy, anti-emetics, analgesics and possibly antibiotics are the main adjuncts to treatment. The prognosis will largely depend on the stage of the disease and the extent to which complications have occurred at the time.