New tests make feline, canine pancreatitis diagnosis easier

Pancreatitis is a common disorder in both cats and dogs, according to pathological examination of pancreas tissue post-mortem.

Feline pancreatitis is often underdiagnosed clinically because of lack of familiarity with clinical signs and the absence of accurate diagnostic tests.

This article will highlight some of the differences between canine and feline pancreatitis as well as discuss some new tests that may make the diagnosis of pancreatitis easier.

Clinical signs

Dogs with acute pancreatitis often present with vomiting, abdominal pain, lethargy and anorexia. Cats, on the other hand, rarely have vomiting and abdominal pain as a sign of pancreatitis.

Clinical pathology

Most dogs with acute pancreatitis have a leukocytosis. Cats with acute pancreatitis can have variable hemograms. Some cats have leukocytosis, some have leukopenia. Some cats are anemic, some are hemoconcentrated. Mild elevations in liver enzymes are common in both dogs and cats with pancreatitis.

These changes in the CBC and serum chemistry are not specific for pancreatitis. Primary gastrointestinal or inflammatory hepatobiliary diseases can cause similar clinical pathology results. In fact, cats with chronic pancreatitis often have concurrent inflammatory bowel disease or cholangiohepatitis (Swift et al. JAVMA 2000; 217:816-818).

Pancreatic markers

Surprisingly, serum TLI (trypsin-like immunoreactivity) is elevated in only 33.3 percent of canine pancreatitis. Serum amylase and lipase are often, but not always, elevated in dogs with acute pancreatitis. Serum levels need to be at least three to four times the upper end of normal to be considered significant. Serum lipase is elevated in 73.3 percent of canine pancreatitis. Amylase is only elevated in 62.1 percent of cases. Therefore, a normal amylase or lipase does not rule out pancreatitis.

Elevated serum amylase and lipase are not specific for pancreatitis. Extrapancreatic sources include gastric and small intestinal mucosa. Amylase and lipase can be falsely elevated in renal failure and gastrointestinal disease. Serum lipase can also be falsely elevated by dexamethasone.

Serum amylase and lipase are worthless in the diagnosis of feline pancreatitis. Serum TLI is currently the most sensitive test available for pancreatitis in cats, but is only elevated in 30-60 percent of cases. Feline TLI can be falsely elevated in renal failure, so it is not specific for pancreatitis. In a recent study, 55 percent of cats with chronic renal failure had a TLI >100 mg/L, the cutoff value for diagnosing pancreatitis (Steiner et al. Proceedings of 20th ACVIM Forum, abstract #235).

Canine pancreatic lipase immunoreactivity (cPLI) is more than 80 percent sensitive in diagnosing pancreatitis. An assay for feline PLI has been described (Wilson et al. Proceedings of 20th ACVIM Forum, abstract #233). Hopefully, this will provide a useful marker for feline pancreatitis.

Diagnostic imaging

Abdominal radiographs may reveal decreased contrast in the right cranial abdomen. Displacement of descending duodenum to the right, stomach to the left, and transverse colon caudally may also be seen.

Abdominal ultrasonography may eveal peripancreatic fluid accumulation. In acute pancreatitis, the pancreas may be hypoechoic surrounded by hyperechoic fat (Figure 1). Chronic pancreatitis may result in a hyperechoic pancreas. An enlarged pancreas by itself is not specific for pancreatitis since pancreatic edema can be seen with portal hypertension or hypoalbuminemia.

A hypoechoic pancreas (PANC) surrounded by hyperechoic fat is seen medial to the duodenum (DUOD) in a dog with acute pancreatitis.

The sensitivity of abdominal ultrasonography in canine pancreatitis was 68 percent in one study. This was more sensitive than abdominal radiography, which was suggestive of pancreatitis in only 24 percent of cases. (Hess et al. JAVMA 1998;213:665-670). In feline pancreatitis, the sensitivity of ultrasonography is only 11-35 percent (Gerhardt et al. JVIM 2001; 15:327-328, Saunders et al. Proceedings 20th ACVIM abstract #10, Ferreri et al. Proceedings of 20th ACVIM abstract #229, Steiner and Williams. Proceedings of 20th ACVIM: pages 562-564).

Pancreatic biopsy

Pancreatic biopsy may be the gold standard for the diagnosis and characterization of pancreatitis. However, most animals with severe acute pancreatitis are poor anesthetic risks for laparoscopy or exploratory laparotomy.

In addition, pancreatitis lesions may be focal and the diagnosis may be missed even if multiple biopsies are taken.

Summary

In dogs, serum lipase and ultrasonography are currently the most useful diagnostic tests for pancreatitis. cPLI may be useful if it becomes more available.

Serum TLI is the most useful diagnostic test for feline pancreatitis, although its sensitivity and specificity is still low. Feline PLI needs to be investigated further in naturally occurring cases of feline pancreatitis.