Feline exocrine pancreatic disease: A diagnostic and therapeutic challenge (Proceedings)
The etiologies of acute necrotizing pancreatitis are probably not yet completely recognized. Biliary tract disease, gastrointestinal tract disease, ischemia, pancreatic ductal obstruction, infection, trauma, organophosphate poisoning, and lipodystrophy all have known associations with the development of acute necrotizing pancreatitis in the cat. Hypercalcemia, idiosyncratic drug reactions, and nutritional causes are suggested but poorly documented causes of the disease.
Concurrent Biliary Tract Disease – Concurrent biliary tract pathology has a known association with acute necrotizing pancreatitis in the cat. Cholangitis is the most important type of biliary tract disease for which an association has been made, but other forms of biliary tract pathology (e.g., stricture, neoplasia, and calculus) have known associations. Epidemiologic studies have shown that cats affected with suppurative cholangitis have significantly increased risk for pancreatitis. The pathogenesis underlying this association is not entirely clear but relates partly to the anatomic and functional relationship between the major pancreatic duct and common bile duct in this species. Unlike the dog, the feline pancreaticobiliary sphincter is a common physiological and anatomic channel at the duodenal papilla. Mechanical or functional obstruction to this common duct readily permits bile reflux into the pancreatic ductal system.Concurrent Gastrointestinal Tract Disease – Like concurrent biliary tract disease, inflammatory bowel disease (IBD) is an important risk factor for the development of acute necrotizing pancreatitis in the cat. Several factors appear to contribute to this association: (1) High incidence of inflammatory bowel disease – IBD is a common disorder in the domestic cat. In some veterinary hospitals and specialty referral centers, IBD is the most common gastrointestinal disorder in cats. (2) Clinical symptomatology of IBD – Vomiting is the most important clinical sign in cats affected with IBD. Chronic vomiting raises intra-duodenal pressure and increases the likelihood of pancreaticobiliary reflux. (3) Pancreaticobiliary anatomy – The pancreaticobiliary sphincter is a common physiological and anatomic channel at the duodenal papilla, thus reflux of duodenal contents would perfuse pancreatic and biliary ductal systems. (4) Intestinal Microflora – Compared to dogs, cats have a much higher concentration of aerobic, anaerobic and total (109 vs. 104 organisms/ml) bacteria in the proximal small intestine. Bacteria readily proliferate in the feline small intestine because of differences in gastrointestinal motility and immunology. If chronic vomiting with IBD permits pancreaticobiliary reflux, a duodenal fluid containing a mixed population of bacteria, bile salts, and activated pancreatic enzyme would perfuse the pancreatic and biliary ductal systems.
Ischemia – Ischemia (e.g., hypotension, cardiac disease) is a cause or consequence of obstructive pancreatitis in the cat. Inflammation and edema reduce the elasticity and distensibility of the pancreas during secretory stimulation. Sustained inflammation increases pancreatic interstitial and ductal pressure which serves to further reduce pancreatic blood flow, organ pH, and tissue viability. Acidic metabolites accumulate within the pancreas because of impaired blood flow Ductal decompression has been shown to restore pancreatic blood flow, tissue pH, and acinar cell function.