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Diagnostic accuracy of canine pancreatitis tests | VETgirl Veterinary Continuing Education Podcasts

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Have a dog presenting to you with abdominal pain and vomiting? In today’s VETgirl online veterinary continuing education podcast, we discuss the diagnostic accuracy of canine pancreatitis tests. Specific tests that are often used to test for canine pancreatitis are the Spec cPL and the SNAP cPL test; however, these tests must be interpreted carefully.

Numerous veterinary publications have previously reported Spec cPL and SNAP cPL results:

o Spec cPL results < 200 ug/L: no pancreatic inflammation
o Spec cPL results ≥ 400 ug/L: supportive of pancreatic inflammation
o Spec cPL 200–399 ug/L: inconclusive  or equivocal for pancreatitis
o SNAP cPL negative: Spec cPL concentration < 200 ug/L
o SNAP cPL positive or abnormal: Spec cPL concentrations > 200 ug/L

Previously, the sensitivity for Spec cPL is reported at 21-82%, while the specificity is reported at 86-100%; however, the majority of these studies have been based on histologic evidence of pancreatic inflammation. As these studies evaluated histologic specimens, it may have resulted in “missed” dogs with mild or moderate pancreatitis (For example, the more severe the pancreatitis, the more severe the histopathologic changes, the more sensitive Spec cPL is!). As for SNAP cPL, the reported sensitivity and specificity was 94% and 77%, respectively.

So, Haworth et al out of University of Melbourne in Australia wanted to evaluate the diagnostic accuracy of these canine pancreatitis tests. They performed a prospective observational cohort study based out of two university teaching hospitals. The authors included 38 dogs divided in 2 groups: those with acute pancreatitis and those without. The goals of this study were to evaluate the sensitivity and specificity of the SNAP cPL and Spec cPL in the acute abdomen canine patient with a diagnosis of pancreatitis. The authors also wanted to evaluate the relationship between Spec cPL and SNAP cPL in the same sample of the individuals in the study.

In Haworth’s study, all of the dogs underwent appropriate tests to diagnose acute pancreatitis, including historical findings, physical examination, chemistry panel, CBC, canine pancreatitis tests (e.g., the Spec cPL and SNAP cPL) and abdominal ultrasonography. The authors were blinded to the results of these pancreatitis test results. Of all the dogs, abdominal pain was the most common clinical sign in all groups (87%, 33/38). Vomiting was seen in 74% (28/38) of the dogs, while diarrhea was seen in 21% (8/38). Abdominal distention was also observed in 18% (7/38) of dogs.

Approximately 29% of the dogs (11/38) were categorized into the acute pancreatitis group. The remaining 71% of dogs (27/38) were classified in the non-acute pancreatitis group. In the acute pancreatitis group, the median age was 9 years (range: 1.5-13 years). Ultrasonographic changes supportive of pancreatitis were reported by the authors in all 11 dogs. In this acute pancreatitis group, 82% (9/11) has a positive SNAP cPL; 2 had a negative SNAP. A Spec cPL was measured in 8/9 of these dogs, and ranged from 320 – 1,000 ug/L with a mean of 748 ug/L. All of these dogs had a Spec cPL of > 200 ug/L. 18% (2/11) of these dogs in the acute pancreatitis group had a negative SNAP cPL; both of these dogs had a Spec cPL of 30 ug/L. Of the 11 dogs, 3 dogs were euthanized, and in 1 dog, necropsy confirmed the diagnosis of acute pancreatitis.

In the non-acute pancreatitis group (27/38 dogs), the median age was 10 years (range 17 weeks to 15 years). Curiously, almost 50% (14/27) of the dogs in the non-acute pancreatitis group had abdominal ultrasonography and surgery. In the non-acute pancreatitis group, 59% (16/27) of dogs had a negative SNAP cPL; these same dogs also had a Spec cPL of < 200 ug/L. An abnormal SNAP cPL was seen in 41% (11/27) of these dogs. Of these 11/27 positive SNAP cPL dogs, 6/10 (60%) had a Spec cPL > 400 ug/L while 4/10 (40%) had a Spec cPL < 200ug/L. Necropsy was performed in 5 of these 27 dogs, and reported no evidence of acute pancreatic inflammation. The diagnosis in these dogs was variable, and included diagnoses such as pancreatic neoplasia (3), intestinal thromboembolism (1), septic peritonitis (2), and lymphoma (1). In the 3 dogs with pancreatic neoplasia (3/38), a normal SNAP cPL and Spec cPL was reported.

Based on the results of this study, the SNAP cPL for clinical diagnosis of pancreatitis had a sensitivity of 82% (9/11) in dogs with pancreatitis, and a specificity of 59% (16/27) in dogs without pancreatitis. As for the Spec cPL, it had a sensitivity of 70% (7/10) in dogs with pancreatiits, and a specificity of 77% (20/26) in dogs without pancreatitis. The authors calculated that the SNAP cPL had a 66% accuracy with a clinical diagnosis of pancreatitis, while for the Spec cPL, it was reported at 75%. So VETgirl’s take? Meh on pancreatitis tests. Based on the results of this study, the authors concluded that both diagnostic tests, the SNAP cPL and Spec cPL, carry a low specificity and agreement for the diagnosis of acute pancreatic inflammation, although Spec cPL demonstrated improved accuracy. There was substantial agreement between the SNAP cPL and Spec cPL results reported in this study, however. Overall, this was a good study evaluating a common diagnostic tool that is commonly misinterpreted. This study also demonstrated how the diagnosis of acute pancreatitis continues to be a clinical challenge. The limitations of this study was that this was a low powered study due to the numbers, although it was a well-designed prospective academic study. But, being that an incorrect diagnosis of pancreatitis was reported in approximately 40% of these dogs – in other words – a false positive, it makes you want to look a the whole picture when diagnosing pancreatitis! Remember, VETgirl’s manta: Veterinary medicine isn’t dumbed down to one SNAP or ELISA test!

References:
1. Huth SP, et al. Analytic validation of an ELISA for measurement of canine pancreas-specific lipase. Vet Clin Pathol 2010; 39:346–353.
2. McCord K, et al. Amulti-institutional study evaluating diagnostic utility of Spec-cPL and SNAP cPL in clinical acute pancreatitis in 84 dogs. J Vet Intern Med 2012; 26:888–896.
3. Beall MJ, et al. Performance validation and method comparison of an in-clinic enzyme-linked immunosorbent assay for the detection of canine pancreatic lipase. J Vet Diagn Invest: 2011; 23:115–119.
4. Haworth MD, Hosgood G, Swindells KL, et al. Diagnostic accuracy of the SNAP and Spec canine pancreatic lipase tests for pancreatitis in dogs presenting with clinical signs of acute abdominal disease. J Vet Emerg Crit Care 2014;24(2):135–143.

Abbreviations:
Spec cPL: specific canine pancreatic lipase

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