Objective—To compare results of a CBC performed on blood samples obtained from healthy dogs and cats by use of standard and microsample collection tubes.
Animals—29 healthy client-owned animals (14 dogs and 15 cats).
Procedures—A blood sample (3 mL) was collected from each animal; 2.5 mL was transferred into a vacuum tube that contained sodium EDTA, and 0.5 mL was transferred into a microsample tube that contained sodium EDTA. Variables evaluated were total numbers of RBCs and WBCs, hemoglobin concentration, Hct, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration (MCHC), mean platelet volume, and plasma total protein concentration as well as neutrophil, lymphocyte, monocyte, eosinophil, basophil, and platelet counts. Results for the 2 types of tube in each species were compared by use of Pearson correlation coefficients, Passing-Bablok regression analysis, and Bland-Altman analysis.
Results—The Pearson correlation coefficient was low for basophil count in cats and moderate, high, or very high for all other variables. Constant and proportional biases were identified for MCHC in dogs by use of Passing-Bablok regression analysis, although the mean difference between types of blood collection tubes was small. No evidence of constant or proportional bias for any other variable was revealed by regression analysis or Bland-Altman analysis.
Conclusions and Clinical Relevance—Samples obtained from healthy dogs and cats by use of microsample blood collection tubes provided clinically equivalent CBC results, compared with results for samples obtained by use of standard blood collection tubes, and minimized the total sample volume collected for diagnostic testing.
Objective—To compare results of biochemical analyses performed on plasma samples obtained from healthy dogs and cats by use of standard and microsample blood collection tubes.
Animals—29 healthy client-owned animals (14 dogs and 15 cats).
Procedures—A blood sample (3 mL) was collected from each animal; 2.5 mL was transferred into a vacuum tube that contained lithium heparin, and 0.5 mL was transferred into a microsample tube that contained lithium heparin. Variables evaluated were albumin, bicarbonate, BUN, calcium, chloride, cholesterol, creatinine, glucose, phosphorus, potassium, sodium, total bilirubin, and total protein concentrations and alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and creatine kinase activities. Results for the 2 types of tubes in each species were compared by use of Pearson correlation coefficients, Passing-Bablok regression analysis, and Bland-Altman analysis.
Results—Data were normally distributed, except for creatine kinase activity of cats. The Pearson correlation coefficient was minimal for total bilirubin concentration in cats and moderate, high, or very high for all other variables. Constant bias for cholesterol and glucose concentration in dogs was identified during Bland-Altman analysis, although the mean difference between types of blood collection tubes was small. No constant or proportional bias for any other variable was revealed by regression analysis or Bland-Altman analysis.
Conclusions and Clinical Relevance—Samples obtained from healthy dogs and cats by use of microsample blood collection tubes that contained lithium heparin provided clinically equivalent biochemical results, compared with results for samples obtained by use of standard blood collection tubes, and minimized the total sample volume collected for diagnostic testing.
OBJECTIVE To investigate the use of canine whole blood (WB) for measurement of ammonia concentration by use of a point-of-care ammonia meter and to compare results of measuring ammonia concentrations in WB, EDTA-anticoagulated WB, and plasma.
ANIMALS 40 client-owned dogs.
PROCEDURES A blood sample (2 mL) was obtained from each dog. One drop of WB was immediately applied to a test strip for evaluation with an ammonia meter. The remainder of the blood sample was placed in an EDTA-containing tube, and 1 drop of EDTA-anticoagulated WB was applied to a test strip. The remaining EDTA-anticoagulated WB sample was centrifuged, and the plasma was harvested and placed on ice. One drop of plasma was applied to a test strip; the remainder of the plasma sample was transported on ice and used for ammonia measurement with a reference laboratory instrument. All samples were tested within 1 hour after sample collection. Results were evaluated to detect significant differences in ammonia concentration.
RESULTS Ammonia concentrations did not differ significantly between WB and EDTA-anticoagulated WB and between plasma samples measured with the meter and reference laboratory instrument. However, median ammonia concentration was significantly higher in plasma than in WB or EDTA-anti-coagulated WB.
CONCLUSIONS AND CLINICAL RELEVANCE Anticoagulant-free WB was a valid sample for measurement by use of the ammonia meter. Plasma samples had higher ammonia concentrations than did WB samples. Results for each sample type should be interpreted by use of specimen- and method-specific reference intervals.
Objective—To compare blood glucose concentrations measured with 2 portable blood glucose meters (PBGMs) validated for use in dogs (PBGM-D) and humans (PBGM-H) and an automated chemistry analyzer.
Sample Population—92 samples of fresh whole blood and plasma from 83 dogs with various diseases.
Procedures—Each PBGM was used to measure whole blood glucose concentration, and the automated analyzer was used to measure plasma glucose concentration. Passing-Bablok linear regression and Bland-Altman plots were used to determine correlations and bias between the PBGMs and the automated analyzer. Calculated acceptability limits based on combined inherent instrument imprecision were used with Bland-Altman plots to determine agreement. Clinical relevance was assessed via error grid analysis.
Results—Although correlation between results of both PBGMs and the standard analyzer was > 0.90, disagreement was greater than could be explained by instrument imprecision alone. Mean difference between PBGM-H and chemistry-analyzer values was −15.8 mg/dL. Mean difference between PBGM-D and chemistry-analyzer values was 2.4 mg/dL. Linear regression analysis revealed proportional bias of PBGM-H (greater disagreement at higher glucose concentrations); no proportional bias was detected for PBGM-D. No constant bias was detected for either PBGM. Error grid analysis revealed all measurements from both PBGMs were within zones without an anticipated effect on clinical outcome.
Conclusions and Clinical Relevance—Neither PBGM had exact agreement with the automated analyzer; however, the disagreement detected did not have serious clinical consequences. Our findings stressed the importance of using the same device for monitoring trends in dogs and using instrument-specific reference ranges.
OBJECTIVE To investigate the precision of an ELISA for measurement of serum cortisol concentration (SCC) in dogs, assess agreement between this ELISA and 2 validated chemiluminescence assays (CLAs), and evaluate the clinical implications of any bias associated with this ELISA when measuring SCC in dogs.
DESIGN Evaluation study.
SAMPLE 75 stored, frozen serum samples from client-owned dogs.
PROCEDURES Enzyme-linked immunosorbent assay precision was evaluated by measuring SCC of pooled serum samples. Agreement with standard methods was evaluated with Spearman rank correlation, Passing-Bablok regression, and Bland-Altman analysis to compare SCCs obtained with the ELISA and the 2 CLAs. An error grid was used to evaluate identified bias.
RESULTS Within-laboratory coefficients of variation for pooled serum samples with low, medium, and high SCCs were 21.4%, 28.9%, and 13.0%, respectively. There was a high correlation between ELISA results (for all samples combined) and results of the 2 CLAs (CLA 1, r = 0.96; CLA 2, r = 0.97), but constant and proportional biases between the ELISA and CLAs were present at all concentrations. Clinically important disagreement between ELISA results and CLA results occurred in 16 of 63 (25%) samples, particularly with low and high SCCs.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the rate of clinical disagreement between the ELISA and CLAs was sufficiently high to recommend that equivocal results obtained with the ELISA be confirmed by a reference laboratory. Further evaluation of analytic performance of the ELISA should focus on samples with very high and very low SCCs.