Pancreatitis

Introduction

Pancreatitis (Image sourced from Bristol Biomed Image Archive with permission)

Pancreatitis occurs following activation of digestive enzymes within the pancreas leading to autodigestion of the gland. Can be referred to as acute or chronic pancreatitis.

Acute pancreatitis is rapid onset inflammation of the pancreas with little or no pathological changes occurring post recovery. This may completely resolve or 'wax and wane' in the future.

Chronic pancreatitis is continued inflammation leading to irreversible pathological changes (fibrosis, atrophy) and possible decreases in function.

The specific cause is usually idiopathic but several risk factors exist including:

A Nutritional basis which refers to obesity, low protein and high fat diets, feeding of ethionine and hypertriglyceridaemia.

Drugs and toxins including L-asparginase, oestrogen, azathioprine, potassium bromide, furosemide, thiazide diuretics, salicylates, tetracyclines, sulphonamides, vinca alkaloids, zinc toxicosis, cholinesterase inhibitor insecticides, cholinergic agonist and hypercalcaemia.

Pancreatic duct obstruction which is caused by biliary calculi, sphincter spasm, duct wall oedema, duodenal wall oedema, neoplasia, parasites, trauma and iatrogenic reasons.

Duodenal juice reflux, pancreatic trauma, ischaemia and reperfusion which includes duodenal juice reflux into the pancreatic duct, surgical intervention, shock, anaemia, venous occlusion and hypotension.

Other risk factors include parasitic (babesiosis), viral, mycoplasmal, end stage renal disease, liver disease and auto-immune diseases.

Cats mainly suffer from mild chronic interstitial pancreatitis.

Introduction Pancreatitis, Acute Haemorrhagic

This term is often interchangeable with acute pancreatic necrosis or acute pancreatitis. The condition can be mild or severe, non-fatal or fatal. It usually occurs as a sudden onset condition, often after ingestion of a meal rich in fat, but this depends on what species the condition occurs.

The Islets of Langerhans may become involved thus causing the signs if insulin insufficiency. Pancreatitis may be initiated by trauma which initiates the leakage of enzymes. It can also present as recurrent acute pancreatitis - repeated inflammation with minimal permanent pathology. In the disease process, proteolytic degradation of pancreatic parenchyma, vascular damage and haemorrhage occur as well as necrosis of fat by lipolytic enzymes in the pancreas and surrounding omentum. These changes are concentrated at  the periphery of lobules and infiltration by leukocytes indicates inflammation. In mild cases oedema of the interstitial tissue occurs. In more severe cases the pancreas is haemorrhagic and oedematous with greyish white areas of necrosis and this may be interspersed with normal parenchyma. The peritoneal cavity may contain blood-stained fluid sometimes with droplets of fat. Due to these large amounts of necrotic debris, infection by microorganisms from the GIT is likely, causing abscesses.

Acute Pancreatitis in other animals

In horses, necrosis and inflammation results due to migration of parasites, usually strongyle larvae, releasing pancreatic enzymes causing autodigestion. Destructive granulomatous pancreatitis is a part of multisystemic eosinophilic epitheliotrophic syndrome.

In pigs suppuration of the pancreas can occasionally arise as an extension from nearby infection, eg. peritonitis and perforated oesophageal ulcers.

Introduction Pancreatitis, Chronic Interstitial

Chronic pancreatitis often occurs following ongoing inflammation with progression to irreversible damage and impaired function. There is usually fibrosis and reduction in acinar mass. This condition can occur in all species as a consequence of obstruction of the pancreatic ducts, vitamin A deficiency may predispose to this. The condition is most common in the dog, but also in cat, horse and cattle. The islets of Langerhans tend to be preserved. If chronic pancreatitis persisits it can lead to Exocrine Pancreatic Insufficiency (EPI). In cats, chronic pancreatitis can also lead to Diabetes Meliitus developing.

Chronic Pancreatitis in other animals

In sheep

Necrosis of exocrine pancreatic cells followed by fibrosis can be caused by zinc toxicosis. Focal pancreatitis may occur during Foot and Mouth disease resulting in diabetes mellitus during recovery.

In horses

Chronic pancreatitis can occur sporadically and is usually a consequence of parasitic migration or from ascending bacterial infection of pancreatic ducts. It can occur alongside chronic eosinophilic gastroenteritis and is usually clinically silent. Organ tends to be replaced by scar tissue.

In cattle

Focal pancreatitis may occur during Foot and Mouth disease resulting in diabetes mellitus during recovery.

Treatment

Acute Treatment

The general treatment involves fluid correction and maintenance while any underlying cause is treated. Support is then given to allow the inflammatory process to subside. Oral feeding should be witheld for a short period in vomiting patients but enteral and parenteral feeding can be well tolerated.

Analgesia should always be given even without signs of pain. Recommended options include subcutaneous pethidine, intravenous or continuous rate infusion morphine or transdermal fentanyl. Dogs can also be given intraperitoneal lidocaine or bupivicaine.

If a pancreatic infection is suspected then antibiotics should be administered, trimethoprim-sulphonamide and enrofloxacin have good penetration to the pancreas.

Food can be gradually introduced with a low protein and fat content as these are more likely to cause signs. Fat can be further introduced if symptoms have still not returned. If signs reoccur then further starvation should be carried out. Total parenteral nutrition can be used to sustain animals that are unable to tolerate food at all.

Cases often require supportive care, aggressive fluid therapy will be needed to treat dehydration and fluid loss from diarrhoea and vomiting. Renal function and potassium levels should be monitored and if necessary potassium should be supplemented. Patients may also develop a metabolic acidosis in acute pancreatitis or be alkalotic due to vomiting. Should diabetes mellitus develop, this may require treatment with insulin. Further management may be required for respiratory distress, bleeding disorders, renal failure, cardiovascular problems and neurological disorders.

Additionally a whole blood or plasma transfusion can be given with severe disease to replace α-macroglobulins. Albumin also provides oncotic support and limits pancreatic ischaemia and oedema.

For short term use in fulminating pancreatitis, corticosteroids can be given alongside fluids. Long term treatment may lead to unwanted complications.

Long-term treatment

In most patients that have one episode, they may only need to avoid fatty foods. Recurrent hypertriglyceridaemia may need pharmacological intervention.

Prognosis

The disease varies widely and the prognosis can vary from full recovery to death. Generally if the case is an uncomplicated single episode patients will make a good recovery.

Literature Search

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Pancreatitis in cats and dogs publications

References

Andrews, A.H, Blowey, R.W, Boyd, H and Eddy, R.G. (2004) Bovine Medicine (Second edition), Blackwell Publishing

Bertone, J. (2006) Equine Geriatric Medicine and Surgery, Elsevier

Blood, D.C. and Studdert, V. P. (1999) Saunders Comprehensive Veterinary Dictionary (2nd Edition), Elsevier Science

Brown, C.M, Bertone, J.J. (2002) The 5-Minute Veterinary Consult- Equine, Lippincott, Williams & Wilkins

Cowart, R.P. and Casteel, S.W. (2001) An Outline of Swine diseases: a handbook, Wiley-Blackwell

Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition), W.B. Saunders Company

Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2), W.B. Saunders Company

Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition), Mosby Elsevier

Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition), BSAVA

Jackson, G.G. and Cockcroft, P.D. (2007) Handbook of Pig Medicine, Saunders Elsevier

Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students University of Liverpool

Merck & Co (2008) The Merck Veterinary Manual Merial

Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier

Sturgess, K. (2003) Notes on Feline Internal Medicine Blackwell Publishing

Tilley, L.P. and Smith, F.W.K.(2004) The 5-minute Veterinary Consult (Third edition) Lippincott, Williams & Wilkins