Analytical validation of radioimmunoassays for the quantification of select pancreatic enzymes in jejunal fluid and fecal extracts from dogs

Pancreatic enzymes, such as trypsin and lipase, are essential for the digestion of dietary components in the small intestine. Measurement of both enzymes in jejunal fluid and fecal specimens from dogs has not been reported and will be a prelude for further investigations. Therefore, the aim of the study was to validate radioimmunoassays (RIAs) for the measurement of canine trypsin-like immunoreactivity (cTLI) and pancreatic lipase immunoreactivity (cPLI) in jejunal fluid and fecal specimens from dogs. Jejunal fluid and fecal specimens were collected from five healthy Beagles. A commercial 125I-RIA was used for measuring cTLI concentrations and an in-house 125I-RIA was modified for the quantification of cPLI in jejunal fluid and fecal specimens. Both RIAs were analytically validated for canine jejunal fluid and fecal specimens by determining dilutional parallelism, spiking recovery, and intra- and inter-assay variability. For both cTLI and cPLI in jejunal fluid, observed-to-expected ratios for dilutional parallelism and spiking recovery ranged from ⩾77.0% to ⩽115.3% and ⩾79.0% to ⩽120.0%, respectively, and from ⩾87.2% to ⩽118.5% and ⩾74.6% to ⩽116.1%, respectively, for fecal specimens. Intra- and inter-assay coefficients of variation (%CV) for both cTLI and cPLI in jejunal fluid were ⩽7.6% and ⩽10.0%, respectively, and were ⩽10.8% and ⩽9.0%, respectively, for fecal specimens. Both RIAs were demonstrated to be linear, accurate, precise, and reproducible for use with jejunal fluid and fecal specimens from dogs. These results are important for the investigation of pancreatic enzyme concentrations in the gastrointestinal lumen in response to changes in dietary components.