Performance validation and method comparison of an in-clinic enzyme-linked immunosorbent assay for the detection of canine pancreatic lipase.

Diagnosis of pancreatitis is often difficult in dogs that present with acute vomiting, anorexia, and abdominal pain, as these clinical signs may occur with a variety of other illnesses. While quantitative reference laboratory methods specific for canine pancreatic lipase are available to aid in diagnosis, results are generally not available until the next day. The objective of the current study was to validate a semiquantitative in-clinic rapid test for the measurement of canine pancreas-specific lipase (cPL) and to compare its performance to the reference lab method. Comparison of the reference method for cPL to the in-clinic assay demonstrated 96-100% agreement for canine serum samples with normal levels of cPL and 88-92% agreement for samples with elevated levels of cPL. Common interfering substances such as bilirubin, lipids, or hemoglobin had no effect on assay performance. Both within-day and day-to-day variations ranged from 10% to 20% of the calculated cPL concentration, which demonstrated a high degree of precision for the in-clinic assay. Performance of 3 lots of the in-clinic assay with the same set of canine serum samples demonstrated high assay reproducibility, with interclass correlation coefficients of ≥0.93. Results of the in-clinic cPL assay, based on both visual and calculated cPL concentrations, were consistent throughout 15 months of storage. The in-clinic test provides immediate, semiquantitative results to supplement existing pancreatitis diagnostics at the time of acute illness. Because the reference and in-clinic methods are aligned, they can be used together as an immediate aid pet-side and as a fully quantitative follow-up test at the reference laboratory.

Analytical validation of an ELISA for measurement of canine pancreas-specific lipase.

BACKGROUND: The diagnosis of canine pancreatitis is challenging. Clinical presentation often includes nonspecific clinical signs, such as vomiting, anorexia, and abdominal discomfort. Increased serum lipase activity can be indicative of pancreatitis; however, it can also be increased with other conditions. An immunoassay for measurement of canine pancreas-specific lipase in canine serum that would be suitable for commercial application and provide rapid results would be beneficial. OBJECTIVE: The goal of this study was to validate the Spec cPL assay, a commercially available ELISA for the quantitative measurement of canine pancreas-specific lipase. METHODS: Dynamic range, dilutional linearity, precision, interfering substances, assay stability, and reproducibility were investigated for analytical validation. The method was compared with the reference assay, canine pancreatic lipase immunoreactivity (cPLI), and included evaluation of a sample population of dogs and bias. RESULTS: Analytical validation showed a dynamic range of 36-954 µg/L; good precision (intra- and interassay coefficient of variation <12%); absence of interference from lipid, hemoglobin, or bilirubin; 12-month kit stability; and good reproducibility. Method comparison showed a positive bias relative to the cPLI reference method; however, the bias can be accommodated by adjustment of decision limits. The upper limit of the reference interval for Spec cPL was determined to be 216 µg/L based on the upper 97.5th percentile of results from 93 clinically healthy, kennel-housed dogs. CONCLUSIONS: Validation data demonstrated that the Spec cPL assay provides reproducible results for canine pancreas-specific lipase. A readily available assay for measurement of this enzyme allows broader clinical utilization of this analytical tool, generating timely results to aid in the diagnosis of canine pancreatitis.

Parallux beta-lactam: a capillary-based fluorescent immunoassay for the determination of penicillin-G, ampicillin, amoxicillin, cloxacillin, cephapirin, and ceftiofur in bovine milk.

An analytical system was developed for detection of antibiotic residues in bovine milk. The method is based on competitive fluorescent immunoassays in glass capillary tubes (U.S. Patent No. 5,624,850). The system consists of an assay cartridge containing 4 glass capillaries, a reagent tray with 4 wells of dried reagents, and a Parallux processor, which processes the assay, reads fluorescent output, and reports test results. Minimum sensitivity for detection of 6 beta-lactam antibiotics in bovine milk was determined to be penicillin-G, 3.2 ppb; ampicillin, 2.9 ppb; amoxicillin, 3.6 ppb; cloxacillin, 7.4 ppb; cephapirin, 16.3 ppb; and ceftiofur, 33.7 ppb. The assay system was also specific and sensitive for detection of incurred residues at U.S. Food and Drug Administration tolerance levels: penicillin-G, 5 ppb; ampicillin, 10 ppb; amoxicillin, 10 ppb; cloxacillin, 10 ppb; cephapirin, 20 ppb; and ceftiofur, 50 ppb. There was no interference in detection of minimum sensitivity levels of antibiotic by the presence of somatic cells at approximately 1 x 10(6) cells/mL. Milk containing 3 x 10(6) cells/mL bacteria commonly found in mastitic milk also showed no interference when tolerance levels of antibiotic were present. There was no detectable interference on results by a wide variety of non-beta-lactam drugs.