Pancreas and Pancreatitis

40 Pancreas and Pancreatitis



Anthony P. Carr



1. What function does the pancreas have?

The exocrine pancreas is responsible for the production of inactive zymogens that become active digestive enzymes (e.g., trypsinogen, chymotrypsinogen, proelastases). Some active enzymes are released including lipase and α-amylase. The pancreas secretes products that are necessary for vitamin B12 and zinc absorption. In addition, it secretes bicarbonate that helps to buffer the acid entering the duodenum from the stomach. Secretion of pancreatic products is stimulated by cholecystokinin and secretin.


2. What is autodigestion and what mechanisms are present in the pancreas to prevent this?

Active digestive enzymes would represent a threat to the pancreas. In the active form, they could lead to digestion of the pancreas itself (autodigestion). Because of this, various mechanisms are in place to prevent this catastrophic event from occurring. The majority of pancreatic enzymes are stored and secreted in an inactive form called zymogens. The zymogens are first secreted into the rough endoplasmic reticulum; this segregates the enzymes from substances in the cell that would be capable of activating the enzyme. They are stored for secreting in granules. The activation of zymogens into active enzymes occurs some physical distance from the pancreas, usually in the gut. The pancreatic cells produce a trypsin inhibitor that could inactivate trypsin activity in the cell. The plasma also contains a variety of factors such as α1-antitrypisin and α2-macroglobulin that can inhibit active proteases.


3. What is the pathogenesis of pancreatitis?

After an insult has occurred that has overwhelmed the ability to prevent autodigestion, inflammation of the pancreas is induced. The enzymes begin to break down the cells and surrounding stroma. Free radicals are generated that cause further damage to the pancreas and surrounding tissues. The inflammation leads to increased permeability, which promotes pancreatic edema. In more severe cases, necrosis of the organ can develop. If the disease is severe enough, multisystemic involvement occurs via the systemic inflammatory response syndrome and by direct effects of circulating active pancreatic enzymes. A generalized increase in permeability results leading to shock, peripheral edema, pulmonary edema, and effusions. Disseminated intravascular coagulation (DIC) can also be a result of the severe injury and inflammation, leading to further organ damage by means of thrombosis.


Depending on many factors, the degree of damage to the pancreas will vary. In general, edematous pancreatitis is differentiated from the hemorrhagic/necrotizing form. The latter has a poor prognosis and is associated with multiple organ involvement, potentially multiorgan failure.


4. What risk factors are there for developing pancreatitis?

Several risk factors have been identified that predispose to pancreatitis. Small-breed dogs such as Miniature Schnauzers, Poodles, and Yorkshire Terriers appear to be predisposed. In some Miniature Schnauzers the increased risk may be the result of hyperlipidemia, a condition known to occur in this breed. Obesity also appears to be a factor that promotes pancreatitis. Feeding a high-fat meal (dietary indiscretion) may in some cases be an underlying cause.


Certain medications and chemicals are also thought to be associated with pancreatitis. Azathioprine, sulfa drugs, furosemide, and potassium bromide are a few of the drugs that have been implicated as a playing a role. The use of cholinesterase inhibitor insecticides is also suspected of being an initiating event. Corticosteroids have been discussed as a potential cause, though the evidence for this is tenuous. Hypercalcemia (either because of a concurrent illness or from calcium injections) is suspected as well.


Concurrent diseases have been implicated as predisposing factors for pancreatitis. These include hyperadrenocorticism, diabetes, prior gastrointestinal disease, and chronic renal failure, although the association in some cases is uncertain. Any condition that leads to poor perfusion could also lead to pancreatitis. Anesthesia with hypotension would be one such scenario.


5. What clinical signs are associated with pancreatitis?

Clinical signs with pancreatitis can be quite variable. It is possible for the disease to be subclinical. The development of clinical signs is dependent on the severity of the disease. In mild cases, lethargy and anorexia may be noted. In the more severe cases, vomiting, depression, abdominal pain, and fever are commonly seen. Other signs noted on occasion are diarrhea, icterus, dehydration, palpable cranial abdominal mass, arrhythmias, and ascites. The most severe cases will present in shock with hypothermia, prolonged capillary refill time, weakness, or collapse. Tachypnea or dyspnea is often present; this can be from pain, noncardiogenic pulmonary edema, pleural effusion, or pulmonary thromboembolism. Tachycardia can be present because of pain, shock, or arrhythmias.


6. How can imaging help in a dog with pancreatitis?

Imaging can be helpful in establishing a diagnosis and determining if certain complications associated with pancreatitis are present. In addition, imaging is necessary to help rule out some of the major differentials for pancreatitis such as gastrointestinal obstruction, intussusception, bile duct obstruction, and splenic torsion.


Radiography can, on occasion, detect certain changes that suggest pancreatitis, though definitive diagnosis is rarely possible and considerable expertise is needed to appreciate the at-times subtle changes present. This includes loss of detail in the area of the pancreas (“ground-glass appearance”), displacement of the stomach to the left, and widening of the angle between pyloric antrum and proximal duodenum. In more advanced cases, ascites will obscure abdominal detail. Pancreatitis is also a major differential diagnosis for dogs with effusion in the abdomen and thorax. Radiographs can also help to investigate dyspnea or tachypnea in these animals by ruling out pulmonary edema and pleural effusion. Normal thoracic radiographs in a hypoxic animal would also be suggestive of pulmonary thromboembolic disease.


Abdominal ultrasound has proved to be a useful tool with pancreatitis and is one of the more sensitive tests for this disease. Changes suggestive of pancreatitis are an enlarged and hypoechoic pancreas sometimes surrounded by an area of hyperechogenicity that is thought to represent peripancreatic fat saponification and necrosis. Localized effusion in the area of the pancreas can also be seen. The common bile duct may be enlarged due to compression of the duct as it runs through the pancreas. It is also possible to assess for such complications of pancreatitis such as pancreatic pseudocysts or abscesses.

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Jul 31, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on Pancreas and Pancreatitis

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