Pancreatitis is a common inflammatory disease of the exocrine pancreas and is currently widely classified into acute, acute-relapsing, and chronic. Clinical severity ranges from mild and self-limiting to fatal. The terminology used in the veterinary literature can cause confusion because the underlying pathological lesions (eg, necrosis, purulent inflammation, chronic active inflammation) cannot be distinguished clinically, and histopathological examination is rarely performed. Therefore, many authors recommend modifying the consensus definitions used in human medicine to clinically classify cases according to the severity of the disease (Table 86.1). Whether mild or severe, acute or chronic, pancreatitis is a common condition in small animal emergency medicine. Because the clinical signs of acute pancreatitis (AP) may resemble surgical disease, and because severe pancreatitis can lead to severe illness and death, recognition and appropriate treatment are essential in the emergency setting.

The cause of pancreatitis in dogs and cats is generally unknown, although many risk factors have been proposed (Box 86.1) . Colocalization of enzyme granules and lysosomal proteases within acinar cells leads to the final central pathway - activation of trypsinogen to trypsin. Mechanisms to prevent inappropriate early activation of trypsin have been established, but these mechanisms become overwhelmed in patients with pancreatitis. Activated trypsin then activates other pancreatic enzymes, thus promoting autodigestion of the gland. The ensuing inflammation may be contained locally and cause complications such as pancreatic necrosis, acute fluid collection, extrahepatic bile duct obstruction (EHBDO), and peritonitis, or it may cause distant systemic effects, propagating a systemic inflammatory response syndrome. (SIRS). Disseminated intravascular coagulation (DIC) and multiple organ dysfunction syndrome (MODS) are potential consequences of a vigorous, uncontrolled inflammatory response.

If an animal survives the inflammatory response to AP, the process can be completely reversed unless the original trigger persists. Even when complete resolution is achieved, AP can recur as an acute relapsing disease, which may eventually resolve or may become a chronic course. The chronic form is progressive and irreversible, with potential consequences of exocrine pancreatic insufficiency (EPI), diabetes mellitus (DM), or both.

Most dogs and cats that develop pancreatitis are over 5 years old, but animals of any age can be affected. Certain dog breeds are considered to be at increased risk (see Box 86.1).

The acute, acute-recurrent and chronic forms of pancreatitis are clinically and historically indistinguishable. Clinical findings are nonspecific and depend on the severity of the disease and the presence of signs of a systemic inflammatory response or multiorgan involvement (see Chapter 159). Chief complaints of dogs include anorexia, vomiting, lethargy and weakness, and to a lesser extent diarrhea. Anorexia and lethargy are more common in cats. Clinically, dogs often become dehydrated. One study reported that 51% of dogs were moderately dehydrated and 46% were dehydrated and hypoperfused (see Chapter 153) [10]. In one study, jaundice due to bile duct obstruction was noted in 26% of dogs with severe acute pancreatitis (SAP). Respiratory distress may result from aspiration pneumonia (see Chapter 37) or acute respiratory distress syndrome (if present). Heat illness is relatively common in dogs (about 32%), but this is less common in cats, and hypothermia is reported more frequently in this species.

In one study, 58% of dogs reported clinical evaluation of abdominal pain. Rectal examination may reveal melasma or blood in the stool. Reported neurological abnormalities include confusion, stupor, convulsions, and seizures, but are uncommon. Physical examination findings in cats are often unremarkable and include dehydration, lethargy, jaundice, and hypothermia.

The presumptive diagnosis of pancreatitis is made by careful integration of historical, clinical, clinical pathology, and diagnostic imaging findings. In many cases, the initial evaluation will be that of an acute abdomen (see Chapter 6) and therefore the initial evaluation focuses on ruling out surgical disease. Definitive diagnosis requires histopathological examination, but this is rarely clinically justified.

Most clinicopathological findings alone are not diagnostic. In cats, concurrent diseases such as hepatolipidemia, inflammatory bowel disease, and inflammatory liver disease are frequently found, especially those associated with chronic disease. These comorbidities may confound the clinician's assessment. Common hematology findings in dogs include leukocytosis, neutrophils, leukocytosis, and thrombocytopenia. In contrast, cats more commonly suffer from anemia and leukopenia. In severe cases, prothrombin time (PT) and partial thromboplastin time (aPTT) are often prolonged (see Chapter 70). Congestion is usually prerenal, but in severe cases there may be evidence of acute kidney injury (see Chapter 94). Cholestasis in both animals may be associated with bile duct obstruction or be due to concurrent primary liver disease in the cat.

In dogs, the two pancreatic ducts enter the duodenum at different locations. In most dogs, the pancreatic duct does not connect with the common bile duct before entering the duodenum. Cats differ in that more commonly a pancreatic duct joins the common bile duct before entering the duodenum. A small percentage of cats may have a second, smaller pancreatic duct that separates into the duodenum. Uncommon variations in dogs include a similar arrangement to that in cats, in that only one duct is present, which connects the common bile duct before entering the duodenum. Variability in pancreatic duct anatomy may partially explain the differences in susceptibility to bile duct obstruction in dogs and cats. Mild hypoalbuminemia is also seen in cats. Hypocalcemia is associated with a worse prognosis, reported to be much lower in cats than in dogs. Despite the lack of overt gastrointestinal signs, hypokalemia is common in cats and is most likely due to long-standing anorexia. Amylase and lipase are rarely elevated in cats with pancreatitis and are not specific markers in either species. Only 26% of dogs with fatal acute pancreatitis had lipemic serum. In one study, hyperglycemia was reported in both species, whereas hypoglycemia in cats was associated with a purulent form of AP.

The canine pancreatic lipase immunoreactivity (PLI) test is the most sensitive and specific serum test currently available for dogs. Studies reported varying sensitivity (21–78%) and specificity (80–100%), but with increasing or decreasing (>200 μg/L Spec cPL) or increasing (>400 μg/L) disease severity. Spec cPL) are the critical values ​​for sensitivity and specificity respectively. The test is thought to be less sensitive in chronic pancreatitis than in acute disease. SNAP cPL, which provides only semiquantitative results (normal or abnormal), may have special application in the emergency room because of its rapid readout.