An Immunoassay for Canine Pancreatic Elastase 1 as an Indicator for Exocrine Pancreatic Insufficiency in Dogs

Abstract

Abstract. The detection of pancreatic elastase 1 in stool samples has become the noninvasive gold standard for the diagnosis of pancreatic insufficiency in humans. Accordingly, the development of a sandwich-ELISA specific for canine pancreatic elastase 1, based on monoclonal antibodies, is presented here. The test has a detection range of 4-240 g canine pancreatic elastase 1/g feces. The intraassay coefficient of variation is 7.4%, and the interassay coefficient of variation is 7.7%. Spiking experiments show that canine elastase 1 is quantitatively detectable in fecal samples. Interestingly, the range of the elastase 1 concentration in canine feces within several days is higher as compared with humans. As the proposed cutoff of 10 g/g is below this variation range in 96.1% of the tested samples, the effect on the test specificity is negligible. Because the test detects neither human nor bovine and porcine elastase 1, pancreatic function can be monitored without interrupting an enzyme replacement therapy.Clinical signs of weight loss, diarrhea, and polyphagia are leading symptoms for malabsorption, usually caused by small intestinal disease/enteritis, and for maldigestion, caused by exocrine pancreatic insufficiency (EPI). 20 Thus, differential diagnosis of EPI requires an organ-specific diagnostic method. The most common cause for EPI is pancreatic acinar atrophy, followed by occasionally relapsing pancreatitis in elderly dogs, leading to EPI if more than 90% of the pancreatic tissue is destroyed. 15,19,20 Various tests are available for the diagnosis of canine EPI. At present, the most frequently applied test is the detection of canine trypsin-like immunoreactivity (cTLI) in dog's serum with a radioimmunoassay. 21,22 This test is most reliable and delivers usually accurate results. It was particularly developed for the diagnosis of EPI in dogs.All other tests are less reliable in terms of sensitivity and specificity, 11 like an enzyme-linked immunosorbent assay (ELISA) for the detection of cTLI and a test for chymotrypsin activity in feces. 7 Similarly, other noninvasive pancreatic function tests (oral fat absorption test, pancreatic proteolytic enzyme activity test, starch tolerance test, BT PABA-test, xylose absorption test) are often misleading because they produce a high proportion of equivocal results. 1,9,20 Most of these tests (with the exception of the tests for serum canine TLI) were adapted from diagnostic procedures

Laboratory Tests for Diagnosis of Gastrointestinal and Pancreatic Diseases

“…A canine-specific ELISA has been developed and validated for the determination of elastase-1 in the stool. 79 However, despite a high sensitivity of 100%, the test has a specificity of only 56.5% for the diagnosis of EPI. 80 Therefore, it is probably not useful for the diagnosis of EPI in dogs.…”

Practical Interpretation and Application of Exocrine Pancreatic Testing in Small Animals

“…A concentration of more than 20 mg/g in feces can be considered a result that excludes EPI, but values less than this are only suggestive of EPI. [74][75][76] Unfortunately, no single test seems to be able to diagnose dogs with subclinical EPI or to be able to predict which dog will go on to develop EPI, even with advanced dynamic testing. 65 …”

Pancreatic acinar atrophy in German shepherd dogs and rough‐coated Collies. Etiopathogenesis, diagnosis and treatment. A review

“…No cross-reactions with bovine or porcine elastase have been detected. Thus the discontinuation of enzyme replacement therapy is not needed (91). The value of faecal elastase in confirming the diagnosis of clinical EPI has been shown both in dogs and in humans (23,32,52,90,93).…”

“…Elastase has been shown to have good intestinal stability, i.e. it does not degrade during the intestinal pagsage (91). Canine faecal elastase (cE1) is a species-and pancreas-specific test.…”