ABSTRACT. We developed a one-step immunochromatography assay kit to measure high levels of canine trypsin-like immunoreactivity (cTLI) for bedside estimation of canine pancreatitis. The serum cTLI level can be determined within 10 min by visual comparison of color strengths in the test and reference zones. The serum cTLI levels determined by this method correlate well with canine TLI-ELISA and can be classified into 3 categories: cTLI levels higher than 60 ng/ml were considered positive; 20-60 ng/ml, weakly positive; and less than 20 ng/ml, negative. Twelve dogs suspected of pancreatitis were examined using this method; 4 dogs were positive, 2 were weakly positive, and 6 were negative. This test can detect a high level of serum cTLI and a positive result in the TLIH test will provide critical information for evaluation of pancreatitis in dogs. KEY WORDS: canine, pancreatitis, TLI.J. Vet. Med. Sci. 69(6): 669-671, 2007 The diagnosis of canine acute pancreatitis is difficult because the clinical signs are not specific and laboratory data can give unreliable results. Serum amylase and/or lipase activity are sometimes used as biochemical makers. However, these markers are not reliable for diagnosis of canine pancreatitis due to their lack of specificity to pancreatic disorders [14]. Recently, it has been reported that assays of immunoreactive pancreatic lipase [12,13] and trypsinogen activation peptide [5] are useful as diagnostic markers for canine pancreatitis. However, relevant information is required quickly for treatment of pancreatitis, and the existing biochemical markers are not rapid enough for bedside diagnosis of pancreatitis because most these assay systems employ enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA).Canine trypsin-like immunoreactivity (cTLI), which includes trypsin and trypsinogen, has been reported to be a more suitable indicator of canine pancreatitis than lipase and amylase activity. Because trypsin and its precursor, trypsinogen, are synthesized and stored by acinar cells in the pancreas, trypsin is believed to be highly specific to pancreatic function without reflecting other diseases [10]. Serum cTLI levels determined by ELISA and RIA are significantly lower in dogs with exocrine pancreatic insufficiency (EPI) than in normal dogs [17,18]. We previously developed a simple bedside test using an immunochromatography system to determine low levels of cTLI in canine sera for diagnosis of EPI [15].On the other hand cTLI levels are apparently high in the early phase of experimentally induced pancreatitis [2,3,10,11,18]. Therefore, a simple method to assay cTLI levels at bedside will be helpful for evaluate not only EPI but also pancreatitis.In this study, we have developed a immunochromatography assay method for determining high levels of cTLI (TLIH test) that is utilizable at bedside without any special equipment. Serum cTLI from dogs suspected of pancreatitis were measured by this TLIH test.In this test kit, 2 monoclonal antibodies that recognize independent epitopes ...