The discrepancy between E canis-IFA, WB analyses, and the commercially available ELISA results for the low-titer serum samples may be related to a high IFA sensitivity or, more likely, a lack of specificity associated with cross-reactivity among Ehrlichia spp.
A 25-amino-acid synthetic peptide (C 6 peptide) derived from an immunodominant conserved region (designated IR 6 ) of the VlsE protein of Borrelia burgdorferi has been identified and used to construct immunoenzyme-based diagnostic procedures. These procedures have excellent sensitivity and specificity. Previous reports have demonstrated the usefulness of the C 6 peptide as an antigen for the serodiagnosis of human and canine Lyme disease. Results indicated that assays based on the C 6 peptide were nonreactive to sera from vaccinated nonexposed animals. The purpose of the present study was to confirm these results in a controlled trial by testing sera from experimentally vaccinated dogs known to be uninfected. Nine specific-pathogen-free beagles were assigned to one of three vaccine groups, each containing three dogs. Each group received one of three commercial Lyme vaccines: RECOMBITEK Lyme (Merial), LymeVax (Fort Dodge Animal Health), and Galaxy Lyme (Schering-Plough Animal Health). Each animal was administered a total of five doses of vaccine over a period of 39 weeks. Serum samples were collected prior to vaccination and then on a weekly basis from weeks 3 to 18 and from weeks 33 to 43. Selected samples were tested by the immunofluorescence assay (IFA) and the Western blot (WB) assay using whole-cell B. burgdorferi antigen extracts, and the results were compared to those obtained with two immunoenzyme-based procedures formatted by using the C 6 peptide. Serum specimens from all animals were reactive to the IFA and WB assay at week 5 and became highly reactive following the administration of multiple doses of vaccine. All serum specimens were uniformly nonreactive in the C 6 peptide immunoenzyme procedures at all time points throughout the study.
Abstract. 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.
The detection of antibody to the Borrelia burgdorferi C 6 peptide by use of enzyme-linked immunoassays is a widely accepted method for the diagnosis of Lyme disease spirochete infection in dogs and in humans. Antibody to the C 6 peptide is highly specific for B. burgdorferi and declines following treatment of dogs and humans exposed to B. burgdorferi. A quantitative assay for determining C 6 antibody levels was developed and used to measure changes in antibody levels following antibiotic treatment of B. burgdorferi antibody-positive nonclinical dogs. One hundred thirty-two client-owned dogs were used in the study; 64 were negative, 53 of 68 positive animals received treatment, and 15 were untreated controls. Test sera were collected at 3, 6, and 12 months from seropositive dogs receiving treatment and untreated controls. Dogs in the treated group were assigned to moderate-to-high (>29 U/ml)-and low (<29 U/ml)-C 6 -level groups because the change in the C 6 level after treatment was dependent on the level prior to treatment. There were significant declines in the 30 dogs with moderate-to-high initial C 6 levels that exceeded the maximal declines of the untreated control dogs in all cases at 6 months (16 data points) and 12 months (29 data points) posttreatment. There was little change in C 6 level following antibiotic therapy in the 23 dogs with low initial C 6 levels. The quantitative C 6 antibody test can be used to measure changes in C 6 antibody levels following treatment of antibody-positive nonclinical dogs.
The measurement of N-terminal pro-B-type natriuretic peptide (NT-proBNP), a biomarker for heart stress detectable in blood, has been shown to have clinical utility in cats with heart disease. A second-generation feline enzyme-linked immunosorbent assay (Cardiopet® proBNP, IDEXX Laboratories Inc., Westbrook, Maine) was developed to measure NT-proBNP in routine feline plasma or serum samples with improved analyte stability. Results of the analytical validation for the second-generation assay are presented. Analytic sensitivity was 10 pmol/l. Accuracy of 103.5% was determined via serial dilutions of 6 plasma samples. Coefficients of variation for intra-assay, interassay, and total precision were in the ranges of 1.6-6.3%, 4.3-8.8%, and 10.1-15.1%, respectively. Repeatability across 2 lots for both serum and plasma had an average coefficient of determination (r(2)) of 0.99 and slope of 1.11. Stability of the analyte was found to be high. In serum samples held at 4°C for 24-72 hr, the mean percent recovery from time zero was ≥99%. In serum samples held at 25°C for 24 hr, the mean percent recovery from time zero was 91.9%, and for 48 hr, 85.6%. A method comparison of the first- and second-generation assays with a clinically characterized population of cats revealed no difference in the tests' ability to differentiate levels of NT-proBNP between normal cats and cats with occult cardiomyopathy (P < 0.001). Results from our study validate that the second-generation feline Cardiopet proBNP assay can measure NT-proBNP in routine feline plasma and serum samples with accuracy and precision.
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