Pancreatitis is an enigmatic disease in feline medicine. Once thought to be rare and insignificant, it is increasingly recognized that inflammation of the pancreas is a common and often severe disease of many cats. Pancreatitis may be found in association with other conditions (such as inflammatory bowel disease, cancers, and diabetes) or may be isolated; it may present as an acute necrotizing syndrome or a chronic, low-grade inflammation and fibrosis. Unlike in dogs, it does not appear to be associated with high fat meals. While some cats may present with classic signs (severe abdominal pain, vomiting, low calcium, etc), others may have mild or vague symptoms.
In many cases, obtaining a definitive diagnosis of pancreatitis is challenging. The gold standard for diagnosis of pancreatitis is pancreatic biopsy. This provides many challenges due to cost, invasiveness, and stability of often seriously ill patients for surgery. It also carries risks of false negatives (ie sampling wrong areas of pancreas) or generating novel pancreatitis due to surgical trauma. Classic modalities (ie serum lipase and amylase) have significant limitations due to the high rate of false positives leading to limited clinical value. Novel diagnostic methods are available, such as ultrasonography, but they also suffer from a less than ideal sensitivity and specificity and require significant operator skill.
fPL (feline pancreatic lipase) is a proprietary test for a pancreas-specific isoform of lipase that has shown to be sensitive for detection of moderate to severe pancreatitis. It is available as both a bedside ELISA test that returns a “normal” or “abnormal” result (SNAP fPL), and as a quantitative test (Spec fPL). The purpose of this study was to compare the SNAP vs Spec fPL to diagnose pancreatitis in an emergency setting.
Cats with clinical suspicion of pancreatitis admitted to a veterinary teaching hospital over a 1 year period were enrolled in the study. SNAP fPL and Spec fPL were measured on all cats. Bloodwork was performed on all cats diagnosed with pancreatitis, and abdominal ultrasound on a subset of them. SNAP and Spec fPL were analyzed on all cats. Cats were diagnosed with pancreatitis based on a combination of clinical signs, blood and ultrasound results, and expert opinion.
111 cats were enrolled in the study, 83% of which were domestic shorthairs. 65% were male, with a median age of 7.25 years.
70% of cats were normal on SNAP fPL and Spec fPL, and 19% were positive for both tests. ~11% of cats had discordant results. Agreement was 97.5% for Spec fPL <3.5ug/L (negative), and 90% for results >5.4ug/L (positive). For results between 3.5-56ug/L, 27% tested positive on SNAP.
Cats were retrospectively classified into 4 groups, with a diagnosis of pancreatitis based on expert opinion using clinical signs and results of blood testing and ultrasonography.
- Group 1: 12 cats (10.8%) who were negative on SNAP and Spec fPL with no clinical signs of pancreatitis
- Group 2: 74 cats (66.7%) with clinical signs of pancreatitis not supported by blood testing, ultrasound, or SNAP/Spec fPL. 84% of these cats were negative on both SNAP and Spec, with the remainder having discordant results. Of the discordant results, most Spec fPLs were between 3.5-5.6ug/L
- Group 3: 21 cats (18.9%) with an expert diagnosis of pancreatitis. 20 cats (95%) had an abnormal SNAP and elevated Spec. One cat had a normal SNAP but elevated Spec.
- Group 4: 4 cats excluded from the study due to negative SNAP and Spec fPL, but clinical signs and ultrasound that could not include or exclude pancreatitis.
Overall, 96% of cats identified as negative for pancreatitis were correctly identified as negative by a combination of SNAP and Spec fPL.
The authors concluded that SNAP fPL represents an appropriate screening test for pancreatitis in cats displaying clinical signs. A negative SNAP result makes pancreatitis unlikely, while a positive should likely prompt further investigation such as a Spec fPL. These tests were not perfect, however, and should be paired with clinical impression, ultrasonography, and other diagnostic test results for the most accurate diagnosis.
There are several limitations to this study. The most significant of these is the lack of gold-standard diagnosis of pancreatitis in any animal (pancreatic biopsy). Consistent standards were not applied to all cats to diagnose pancreatitis (for example, not all cats received an abdominal ultrasound). The retrospective nature of the study posed an additional limitation. The four cats in group number 4 that were excluded may also have represented false negatives, that may have altered the statistics. Prospective studies with consistent diagnostic criteria and a larger sample size are needed to definitively determine the role of Spec and SNAP fPL in practice. (MRK)