Performance evaluation of a Test&Treat rapid detection kit for the diagnosis of septic effusions in dogs and cats.

OBJECTIVE: To evaluate the sensitivity and specificity of a veterinary point-of-care (POC) luminometer-based kit for the diagnosis of septic peritoneal or pleural effusion in dogs and cats. DESIGN: Prospective study performed between January 2020 and July 2021. SETTING: University teaching hospital. ANIMALS: Forty-eight animals with naturally occurring peritoneal or pleural effusion collected by aseptic abdominocentesis or thoracocentesis. PROCEDURES: Effusion samples were split into filtered (using a 10-micron filter) and unfiltered aliquots and analyzed by the POC instrument according to the manufacturer's instructions and following variable incubation periods. Samples were also plated aerobically on standard and blood agar plates. Proprietary reagents were added to samples, causing bacterial ATP to generate bioluminescence that is detected by the luminometer. Bioluminescence values (relative light units [RLUs]) were recorded and compared with the presence of bacterial growth on the culture plates. Nucleated cell counts in native and filtered effusion samples were recorded. RESULTS: Twenty-one samples were septic based on positive culture. RLUs were higher in septic effusions for filtered and native effusions compared with sterile effusions. The use of a filter reduced cell counts. In filtered samples incubated for 30 minutes before testing, the sensitivity and specificity of the luminometer for diagnosis of infection in cavitary effusions were 81% and 82%, respectively, using a cutoff of 12,202 RLUs. CONCLUSIONS: The luminometer kit evaluated in this study represents a viable screening tool for diagnosis of septic cavitary effusions and could be used in conjunction with other POC diagnostics to support the rapid diagnosis of infection.

Comparison of a commercially available veterinary digital refractometer to analogue refractometer and laboratory chemistry analyzer in the evaluation of canine serum total protein.

OBJECTIVE: To assess the agreement between measurements of total protein (TP) concentrations in canine serum samples between a commercially available veterinary digital refractometer (DR), an analog handheld refractometer (AR), and a laboratory-based chemistry analyzer (LAB). An additional objective was to assess the effects of various potential interferents (ie, hyperbilirubinemia, increased BUN, hyperglycemia, hemolysis, and lipemia) on DR measurements. SAMPLE: 108 canine serum samples. PROCEDURES: Serum samples were measured in duplicate on the DR, which reported TP concentration, assessed via optical reflectance and critical angle measurement. These serum samples were also assessed on the AR and LAB for comparison. Serum samples with grossly visible lipemia, hemolysis, and icterus were noted. Medical records were retrospectively assessed to determine concentrations of BUN, glucose, and bilirubin. RESULTS: Method comparisons among the various data generated by the analyzers were completed using linear regression, Bland Altman, and calculation of intraclass coefficients. Mean bias between DRTP and LABTP in samples without potential interferents was 0.54 g/dL with 95% limits of agreement of -0.17 to 1.27 g/dL. One-third of DRTP samples without potential interferents had > 10% difference from their LABTP comparison. Interferents, particularly marked hyperglycemia, can result in inaccurate measurements on the DR. CLINICAL RELEVANCE: There was a statistically significant difference between DRTP and LABTP measurements. TP measurements in samples with any potential interferent, particularly hyperglycemia, should be assessed cautiously on DR and AR.

Effects of potential confounding variables on accuracy of a commercially available veterinary point-of-care hematocrit meter in the evaluation of blood samples from dogs and cats.

OBJECTIVE: To assess the agreement in measurements of Hct values and hemoglobin (Hgb) concentrations in blood samples from dogs and cats between a commercially available veterinary point-of-care (POC) Hct meter and a laboratory-based (LAB) analyzer and to determine the effects of various conditions (ie, lipemia, hyperbilirubinemia, hemolysis, autoagglutination, and reticulocytosis) on the accuracy of the POC meter. SAMPLES: Blood samples from 86 dogs and 18 cats. PROCEDURES: Blood samples were run in duplicate on the POC meter, which reported Hgb concentration, measured via optical reflectance, and a calculated Hct value. The POC meter results were compared with results from a LAB analyzer. Blood samples with grossly visible lipemia, icterus, hemolysis, and autoagglutination were noted. RESULTS: Mean ± SD values for LAB Hct were 33.9 ± 15.73% (range, 3.9% to 75.8%), and for LAB Hgb were 11.2 ± 5.4 g/dL (range, 1 to 24.6 g/dL). Mean bias between POC Hct and LAB Hct values was -1.8% with 95% limits of agreement (LOAs) of -11.1% to 7.5% and between POC Hgb and LAB Hgb concentrations was -0.5 g/dL with 95% LOAs of -3.8 to 2.8 g/dL. There was no influence of lipemia (14 samples), icterus (23), autoagglutination (14), hemolysis (12), or high reticulocyte count (15) on the accuracy of the POC meter. The POC meter was unable to read 13 blood samples; 9 had a LAB Hct ≤ 12%, and 4 had a LAB Hct concentration between 13% and 17%. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, measurements from the POC meter had good agreement with those from the LAB analyzer. However, LOAs were fairly wide, indicating that there may be clinically important differences between measurements from the POC meter and LAB analyzer.