Although pancreatitis is a common disease in human beings, an estimated 90% of clinical or subclinical cases remain undiagnosed. Similarly, pancreatitis is a common gastrointestinal (GI) disorder in both dogs and cats, that can be assumed to remain undiagnosed in many cases. This is partly due to the nonspecific clinical presentation of canine and feline patients with pancreatitis, but also because a highly sensitive and specific diagnostic test for this disease has not been available until now.

Sensitivities and specificities of different diagnostic tests for canine pancreatitis were recently compared. Serum amylase activity showed a specificity of 57% and sensitivity of 62%, while serum lipase activity showed specificity of only 55% and a sensitivity of 73%. Almost 50% of dogs with an elevated serum amylase or lipase activity did not have pancreatitis.

The situation is even worse in cats, where serum amylase and lipase activities have been shown to have no clinical usefulness for diagnosis of feline pancreatitis. Serum feline trypsin-like immunoreactivity (fTLI) concentration, while highly specific for feline pancreatitis only has a sensitivity of 30 to 60%. Thus, serum TLI is still the most sensitive diagnostic tool currently available for pancreatitis in cats.

Recently, new assays for measurement of serum pancreatic lipase immunoreactivity (PLI) have been developed and validated for both dogs and cats. Serum canine PLI (cPLI) has been shown to be highly specific for exocrine pancreatic function, and was highly sensitive for canine pancreatitis at the cut-off value of 200 µg/L. When compared to this test, sensitivities of serum cTLI concentration and serum lipase activity were much lower. Dogs with renal failure had normal cPLI, so this test can still be used to diagnose pancreatitis in these patients. To date, clinical experience with the cPLI test has been excellent. The cPLI test is highly sensitive for canine pancreatitis.

Serum fPLI has been evaluated in cats with experimental pancreatitis. In these cats, serum fPLI returned to normal concentrations many days after the fTLI, indicating that this test is likely to be more sensitive than is serum TLI concentration. Initial results in feline clinical cases indicate that a serum fPLI concentration above 10 µg/L is highly suggestive of feline pancreatitis. However, as chronic small intestinal disease possibly compensated by chronic pancreatitis is more common than primary pancreatitis in cats, feline cases with chronic GI disease should also be assessed with measurements of serum cobalamin and folate concentrations. For both dogs and cats, serum TLI concentration remains the test of choice for exocrine pancreatic insufficiency (EPI).

In summary, serum PLI measurements have recently been validated for dogs and cats and assays are commercially available. Serum cPLI concentration has been shown to be both highly specific for EPI and highly sensitive for canine pancreatitis. Serum fPLI concentration has been elevated in a few cases of experimental and spontaneous pancreatitis in cats. The PLI test requires 0.5 mL of serum collected after 12 hour period of fasting.

[Excepted from material of Dr. David Williams]