ASVCP Guidelines: Principles of Quality Assurance and Standards for Veterinary Clinical Pathology (version 3.0): Developed by the American Society for Veterinary Clinical Pathology's (ASVCP) Quality Assurance and Laboratory Standards (QALS) Committee

Scientific and Regulatory Policy Committee Points to Consider: Biological Sample Retention From Nonclinical Toxicity Studies

Samples of biologic specimens and their derivatives (eg, wet tissues, paraffin-embedded tissue blocks, histology slides, frozen tissues, whole blood, serum/plasma, and urine) are routinely collected during the course of nonclinical toxicity studies. Good Laboratory Practice regulations and/or guidance specify minimum requirements for specimen retention duration, with the caveat that retention of biologic specimens need not extend beyond the duration of sample stability. However, limited availability of published data regarding stability for various purposes following storage of each specimen type has resulted in confusion, uncertainty, and inconsistency as to the appropriate duration for storage of these specimens. To address these issues, a working group of the Society of Toxicologic Pathology Scientific and Regulatory Policy Committee was formed to review published information, regulations, and guidance pertinent to this topic and to summarize the current practices and rationales for retention duration through a survey-based approach. Information regarding experiences reaccessing biologic specimens and performing sample stability investigations was also collected. Based on this combined information, the working group developed several points to consider that may be referenced when developing or revising sample retention practices. [Box: see text].

Validation of a commercial human ELISA to measure hyaluronic acid concentration in feline plasma

Our goal was to validate a human hyaluronic acid (HA) ELISA (Hyaluronic acid plus ELISA; TECOmedical Group) for use in feline plasma. Plasma from 5 healthy cats and 5 critically ill cats was used for validation of the assay. Validation methods performed included intra- and inter-assay variability, spike-and-recovery, and dilutional linearity. All measurements were performed in duplicate. The precision study revealed good intra-assay CV of 7.4-8.9%; inter-assay CV was 3.4-4.2%. Extraction efficiency via spiking tests yielded mean recovery of 89.6%. The assay met criteria for acceptable linearity using 3 serial dilutions. Our results demonstrate that this commercial HA ELISA had acceptable analytical performance using feline plasma and could be a useful tool in the veterinary clinical research setting.

Validation study of canine serum cortisol measurement with the Immulite 2000 Xpi cortisol immunoassay

We report the results of validation of canine serum cortisol determination with the Immulite 2000 Xpi cortisol immunoassay (Siemens), with characterization of precision (CV), accuracy (spiking-recovery [SR] bias), and observed total error (TEo = bias + 2CV) across the reportable range, specifically at the most common interpretation thresholds for dynamic testing. Imprecision increased at increasing rate with decreasing serum cortisol concentration and bias was low, resulting in increasing TEo with decreasing serum cortisol concentration. Inter-laboratory comparison study allowed for determination of range-based bias (RB) and average bias (AB). At 38.6 and 552 nmol/L (1.4 and 20 μg/dL), between-run CV was 10% and 7.5%, respectively, and TEo ~30% and ~20%, respectively (TEo remained similar regardless of the considered bias: SR, RB, or AB). These analytical performance parameters should be considered in the interpretation of results and for future expert consensus discussions to determine recommendations for allowable total error (TEa). Importantly, the commonly used thresholds for interpretation of results were determined ~40 y ago with different methods of measurements and computation, hence updating is desirable. Quality control material (QCM) had between-run imprecision of 4% for QCM1 and 7% for QCM2; the bias was minimal for both levels. Acceptable QC rules are heavily dependent on the desired TEa for the QCM system (TEaQCM), itself limited by the desired clinical TEa. At low TEaQCM (20-33%), almost no rules were acceptable, whereas at high TEaQCM (50%), almost all rules were acceptable; further investigation is needed to determine which TEaQCM can be guaranteed by simple QC rules.

A novel canine nuclear magnetic resonance spectroscopy-based metabolomics platform: Validation and sample handling

BACKGROUND

Metabolomics has been proven to be an invaluable research tool by providing comprehensive insight into systemic metabolism. However, the lack of scalable and quantitative methods with known reference intervals (RIs) and documented reproducibility has prevented the use of metabolomics in the clinical setting.

OBJECTIVE

The objective of this study was to validate the developed quantitative nuclear magnetic resonance (NMR) spectroscopy-based metabolomics platform for canine serum and plasma samples and determine optimal sample handling conditions for its use.

METHODS

Altogether, 8247 canine samples were analyzed using a Bruker's 500 MHz NMR spectrometer. Using statistical approaches derived from international guidelines, we studied method precision, measurand stability in various long- and short-term storage conditions, as well as the effect of prolonged contact with red blood cells (RBCs), and differences among blood collection tubes. We also screened interferences with lipemia, hemolysis, and bilirubinemia. The results were compared against routine clinical chemistry methods, and RIs were defined for all measurands.

RESULTS

We determined RIs for 123 measurands, most of which were previously unpublished. The reproducibility of the results of the NMR platform appeared generally outstanding, and the integrity of the results can be ensured by following standard blood drawing and processing guidelines.

CONCLUSIONS

Owing to the advantages of quantitative results, high reproducibility, and scalability, this canine metabolomics platform holds great potential for numerous clinical and research applications to improve canine health and well-being.

Effect of age, sex, and body size on the blood biochemistry and physiological constants of dogs from 4 wk. to > 52 wk. of age

BACKGROUND

Blood biochemistry and reference intervals help to differentiate between healthy and ill dogs as well as to provide information for the prognosis, evaluation, and monitoring; however, these intervals are often obtained from adult animals. It is essential to understand that puppies and adults are physiologically different, which justifies the need to obtain age-specific biochemical reference intervals. The aim of this research was to assess the potential effect of age, sex, body size, and their interaction on routine biochemical analytes and physiological constants (body temperature, heart rate, and respiratory rate). To carry out the research, we selected 197 healthy dogs of both sexes and different body sizes (small, medium and large) classified by age: group I (4-8 wk), group II (9-24 wk), group III (25-52 wk), and group IV (> 52 wk). The biochemical analysis included the measurement of the enzymatic activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and the concentrations of cholesterol, triglycerides, total proteins, albumin, globulins, glucose, urea, and creatinine. Statistical analyses used analysis of variance (ANOVA) and a general linear model (GLM), which allows the comparison of multiple factors at two or more levels (p < 0.05).

RESULTS

The results of this study showed that ALT, total protein, albumin, globulin, urea, creatinine, and body temperature levels were lower in puppies than in adult dogs of group IV (p < 0.05), while the enzymatic activity of ALP, LDH, glucose concentration, and heart rate were higher. Whereas sex, body size and the interaction did not show a significant effect (p > 0.05).

CONCLUSIONS

Some biochemical components are influenced by age. For this reason, this manuscript contributes with additional data for the clinical interpretation of blood biochemical results in puppies.

Comparison of STA-NeoPTimal (Stago) and STA-Neoplastine CI Plus (Stago) thromboplastin reagents using a STA Satellite Max analyzer to measure prothrombin times in dogs

BACKGROUND

Different thromboplastins are available to measure prothrombin time (PT). Stago coagulation analyzers and reagents are currently used in veterinary laboratories and enable PT measurements to explore the coagulation cascade (extrinsic pathway).

OBJECTIVES

The main objective was to compare PT measurements obtained with the STA-NeoPTimal reagent with the commonly used STA-Neoplastine CI Plus reagent. The secondary objective was to compare the PT ratio with the international normalized ratio (INR) calculated from our derived clotting times.

METHODS

Analytical performance was evaluated with intra-assay and inter-assay precision. Seventy-two individual canine plasma samples were collected. Each sample was tested with both thromboplastins, using an STA Satellite Max analyzer. The PT, PT ratio, and INR values obtained with the two reagents were compared using Passing-Bablok regression for correlations and Bland-Altman plots for method agreements.

RESULTS

The analytical performance of STA-NeoPTimal reagent was acceptable. Compared with the STA-Neoplastine CI Plus reagent, the STA-NeoPTimal reagent showed a positive proportional bias for PT values. Narrow range analyses showed good agreement for normal PT values (less than 9.5 seconds, internal reference cutoff with STA-Neoplastine CI Plus), and clinical concordance was achieved. When PT was prolonged (more than 9.5 seconds), PT increases were more marked with the STA-NeoPTimal reagent. Agreement was good for INR values across the whole range of PT results.

CONCLUSION

STA-NeoPTimal can be reliably implemented in veterinary laboratories for canine PT measurements, as agreement between the PT results measured with the two reagents was clinically acceptable.

Reference Intervals for Selected Hematology and Clinical Chemistry Measurands in Temminck's Pangolin (Smutsia temminckii)

Pangolins are the world's most trafficked non-human mammals. A significant number of Temminck's pangolins (Smutsia temminckii) are presented for veterinary care and rehabilitation in southern Africa. Little is known about the physiology and normal health of this species, making diagnosis and medical management difficult. This study aimed to establish reference intervals (RIs) for hematology and plasma clinical chemistry in the Temminck's pangolin. RIs were generated according to international guidelines using samples from 27 healthy free-living (n = 18) and rehabilitated (n = 9) pangolins. Hematology was performed using the Abaxis VetScan HM5 analyzer with manual differentials; clinical chemistry was performed using heparin plasma on the Abaxis VetScan VS2 and Cobas Integra 400 Plus analyzers. Hematology RIs were: RBC 3.88-8.31 × 10¹²/L, HGB 73-150 g/L, HCT 26-51%, MCV 59-72 fL, MCH 15.6-21.4 pg, MCHC 257-325 g/L, RDW 14.3-19.1%, WBC 1.80-10.71 × 10⁹/L. Vetscan VS2 clinical chemistry RIs were: albumin 27-41 g/L, ALP 26-100 U/L, ALT 25-307 U/L, amylase 267-826 U/L, bilirubin 4-10 μmol/L, calcium 2.1-2.2 mmol/L, globulin 21-55 g/L, glucose 3.8-10.0 mmol/L, phosphate 1.3-2.6 mmol/L, potassium 3.6-5.9 mmol/L, sodium 132-140 mmol/L total protein 52-84 g/L, and urea 5.3-11.4 mmol/L. RIs for creatinine were not calculated as analytical imprecision exceeded analytical performance goals. Cobas Integra clinical chemistry RIs were: albumin 22-33 g/L, ALP 20-104 U/L, ALT 17-291 U/L, amylase 466-1,533 U/L, bilirubin 1-14 μmol/L, calcium 2.0-2.4 mmol/L, creatinine <58 μmol/L, globulin 23-49 g/L, glucose 3.6-10.1 mmol/L, phosphate 1.0-2.2 mmol/L, potassium 3.1-5.8 mmol/L, sodium 137-150 mmol/L, total protein 47-72 g/L, and urea 6.0-12.5 mmol/L. There was significant bias between the two chemistry analyzers for several measurands. Differences were found for some analytes between free-living and rehabilitated animals, probably reflecting differences in nutrition and hydration. These are the first RIs generated for Temminck's pangolin. These results will allow veterinarians to better determine pangolin health status, formulate optimal treatment plans and increase patient survival rates in this endangered species.

Validation of the Sysmex XN-V hematology analyzer for canine specimens

Background

The Sysmex XN‐V is derived from the new Sysmex XN series of human hematology analyzers. The main changes from the previously validated XT‐2000iV analyzer include an optic‐fluorescent analysis for platelets and nucleated RBC count.

Objective

We aimed to validate the Sysmex XN‐V for canine blood according to American College for Veterinary Clinical Pathology and International Council for Standardization in Hematology recommendations.

Materials and Methods

Canine EDTA blood specimens and quality control material were analyzed on the Sysmex XN‐V to evaluate imprecision, bias, linearity, a comparison with the XT‐2000iV analyzer, interference effects, carry‐over, and stability. We also verified previously established Sysmex XT‐2000iV reference intervals (RIs).

Results

Imprecision and bias were low (<5%) for most variables. Observed total error was lower than allowable total error for most measured variables except lymphocytes and monocytes. Visually determined linearity was excellent for all variables, except for lymphocytes. The correlation between the XN‐V and XT‐2000iV analyzers was high (>0.93) for all variables except MCHC and reticulocyte indices. Correlations between the Sysmex XN‐V and manual differential counts were good for neutrophils and eosinophils, acceptable for lymphocytes, and fair for monocytes. Hemolysis, lipemia, and to a lesser extent icterus, had significant effects on measured hemoglobin concentration and associated variables. Carry‐over was not visually observed for any variable. Changes in the Sysmex XN‐V measurements after storage at 4℃ and 24℃ were similar to those described for the Sysmex XT‐2000iV analyzer. The previously established Sysmex XT‐2000iV RIs can be used to interpret results from the Sysmex XN‐V analyzer for most variables except red blood cell distribution width and mean platelet volume.

Conclusions

The performance of the Sysmex XN‐V analyzer was excellent and compared favorably with the Sysmex XT‐2000iV analyzer.

Differential white blood cell counts in rabbits: a comparison of the Advia 2120 and a manual method

We evaluated the performance of the Advia 2120 (Siemens) differential leukocyte count (A-Diff) compared to the manual method (M-Diff) in rabbits. EDTA-anticoagulated blood samples collected for diagnostic purposes were analyzed within 6 h of collection. The M-Diff was performed blindly by 2 observers on blood smears by counting 200 cells. We initially included 117 samples; 25 samples were excluded because of suboptimal gating of leukocytes in the Advia peroxidase cytogram or poor blood smear quality. The correlation between the A-Diff and M-Diff was very high for heterophils (r = 0.924, p < 0.001) and lymphocytes (r = 0.903, p < 0.001), high for basophils (r = 0.823, p < 0.001), moderate for monocytes (r = 0.645, p < 0.001), and low for eosinophils (r = 0.336, p = 0.001). The Passing-Bablok regression analyses revealed a small-to-moderate constant error for lymphocytes and a slight constant error for basophils. Small proportional errors were detected for heterophils, lymphocytes, and eosinophils. The Bland-Altman analyses revealed that the Advia significantly underestimates heterophils and overestimates lymphocytes compared to M-Diff. The biases for the other leukocytes were minimal and likely clinical insignificant; however, our results, particularly for eosinophils, should be interpreted cautiously given the observed low percentages in our samples. Given the observed biases in heterophil and lymphocyte percentages in the Advia 2120 CBC results in rabbits, method-specific reference intervals should be used. The Advia can recognize leporine basophils. Evaluation of blood smears is still recommended to investigate abnormal results and erroneous cytograms reported by the Advia.

A comparison study between the results of the Siemens ADVIA 120 analyzer and the manual method for differential leukocyte counts in sheep

BACKGROUND

The ADVIA 120 is a widely used hematology analyzer, which has not been previously validated for determining differential leukocyte counts in sheep.

OBJECTIVES

We aimed to compare differential leukocyte counts on the ADVIA 120 (A-Diff) with counts obtained using the manual method (M-Diff) in sheep.

METHODS

Ethylenediaminetetraacetic acid-anticoagulated blood samples analyzed within 4 hours of collection were used. Samples with inappropriately filled tubes, detectable clots, overtly erroneous ADVIA peroxidase cytograms, and poor-quality blood smears were excluded from the study. Two independent observers compared the results of the A-Diff with those of the M-Diff. The M-diff was performed by counting 200 leukocytes on a blood smear.

RESULTS

Overall, 88 samples (44 rams and 44 ewes) were included. The correlation between the A-Diff and M-Diff was high for neutrophils (r = .873, P < .001), lymphocytes (r = .863, P < .001), and eosinophils (r = .750, P < .001), and low for monocytes (r = .212, P = .048). The Passing-Bablok regression analyses revealed constant error for eosinophils [1.17%; 95% confidence interval (CI): 0.67%, 1.55%] and proportional error for lymphocytes (0.84; 95% CI: 0.74, 0.95) and eosinophils (0.85; 95% CI: 0.74, 0.96). The Bland-Altman analyses revealed negative biases of 2.4% and 3.0% for neutrophils and lymphocytes, respectively, and positive biases of 3.2% and 0.8% for monocytes and eosinophils, respectively. The extremely low basophil percentages precluded a meaningful method comparison for this leukocyte type.

CONCLUSIONS

The ADVIA 120 appears to perform well for determining neutrophil, lymphocyte, and eosinophil percentages in sheep as compared with the manual method. However, blood smear examinations are recommended for the confirmation of abnormal differential leukocyte count results.

Analytical performance and method comparison of a quantitative point-of-care immunoassay for measurement of bile acids in cats and dogs

Point-of-care analyzers (POCAs) for quantitative assessment of bile acids (BAs) are scarce in veterinary medicine. We evaluated the Fuji Dri-Chem Immuno AU10V analyzer and v-BA test kit (Fujifilm) for detection of feline and canine total serum BA concentration. Results were compared with a 5th-generation assay as reference method and a 3rd-generation assay, both run on a bench-top analyzer. Analytical performance was assessed at 3 different concentration ranges, and with interferences. For method comparison, samples of 60 healthy and diseased cats and 64 dogs were included. Linearity was demonstrated for a BA concentration up to 130 µmol/L in cats (r = 0.99) and 110 µmol/L in dogs (r = 0.99). The analyzer showed high precision near the lower limit of quantification of 2 µmol/L reported by the manufacturer. Intra- and inter-assay coefficients of variation were < 5% for both species and all concentrations. Interferences were observed for bilirubin (800 mg/L) and lipid (4 g/L). There was excellent correlation with the reference method for feline (rs = 0.98) and canine samples (rs = 0.97), with proportional biases of 6.7% and -1.3%, respectively. However, a large bias (44.1%) was noted when the POCA was compared to the 3rd-generation assay. Total observed error was less than total allowable error at the 3 concentrations. The POCA reliably detected feline and canine BA in clinically relevant concentrations.

Postmortem Vitreous Humor Analysis in the Dog, Cat, and Horse

Postmortem chemistry can be a useful ancillary technique that the forensic pathologist can use during a death investigation. In stark contrast, there is limited information available for use of postmortem vitreous humor analysis in animals. In order to use postmortem vitreous humor in veterinary forensic investigations, validation of a method to analyze vitreous humor is required. The goal of this study was to determine the precision, bias, TEobs, and sigma (σ) of the Element DC chemistry analyzer, assess its precision using vitreous humor collected postmortem from dogs, cats, and horses, and assess the stability of postmortem vitreous humor from all 3 species. Analysis of quality control material (QCM) and pooled vitreous humor samples for the three species was used to test for sodium (Na), chloride (Cl), potassium (K), magnesium (Mg), creatinine (Crea), and blood/vitreous urea nitrogen (BUN/VUN). Analysis of QCM showed that the Element DC was both precise and accurate. When analyzing the pooled vitreous humors, most within-run CVs were found to be <5% and the between-run CVs for 5 out of 6 analytes were all found to be <5% for the dog, cat, and horse. In all three species, capped samples of vitreous humor were stable out of the refrigerator for up to 5hr. The results of this study show that the Element DC can successfully be used to analyze postmortem vitreous humor from the dog, cat, and horse.

Evaluation of Urinary Big Endothelin-1 in Feline Spontaneous CKD

Simple Summary

Chronic kidney disease is a common and progressive disease of elderly cats. It is a cause of pet suffering and owner expense. Biologic biomarkers for early diagnosis and for noninvasive evaluation of kidney damage are certainly useful in both research and clinical practice. In this study, we evaluated the biomarker big endotelin-1 in the urine of cats affected with chronic kidney disease. Big endothelin-1 is molecule linked to inflammation and pressure regulation, and it was not previously evaluated in nephropathic cats. We found that urinary big endothelin was increased in patients at late stage of the disease and in patients with proteinuria (a marker of kidney damage). Despite that, big endothelin 1 seemed not to be a useful biomarker for disease progression. According to results of this preliminary study, we suggest this biomarker for future research on feline kidney disease.

Abstract

The endothelin-1 (ET-1) system has been implicated in the development and progression of chronic kidney disease (CKD). No information on big ET-1 in feline urine is available. The purpose of this study was to evaluate if urinary big endothelin-1 (bigET-1) is associated with feline CKD. Sixty urine samples were prospectively collected from 13 healthy cats at risk of developing CKD and 22 cats with CKD of different International Renal Interest Society (IRIS) stages (1–4). Urinary bigET-1 was measured using a commercially available ELISA. BigET-1 normalized to urine creatinine (bigET-1:UC) was compared amongst stages and substages, as proposed by IRIS, and correlated with serum creatinine concentration, proteinuria and blood pressure. BigET-1:UC at the time of inclusion was compared between cats that remained stable and cats that progressed after 12 months. BigET-1:UC was significantly higher (p = 0.002) in cats at IRIS stages 3–4 (median: 21.9; range: 1.88–55.6), compared to all other stages, and in proteinuric (n = 8, median: 11.0; range: 0.00–46.4) compared with nonproteinuric cats (n = 38 median: 0.33; range: 0.00–55.6) (p = 0.029). BigET-1:UC was not associated with CKD progression. Urinary bigET-1 increased in advanced stages of CKD and in proteinuric patients, suggesting that ET-1 may be indicative of the severity of feline CKD.

The Canine Erythrocyte Sedimentation Rate (ESR): Evaluation of a Point-of-Care Testing Device (MINIPET DIESSE)

The erythrocyte sedimentation rate (ESR) in canine medicine has been replaced by the evaluation of a few sensitive markers of the acute-phase proteins. The aim of the study was to evaluate the ESR using a point-of-care (MINIPET, DIESSE Diagnostica Senese S.p.A.) device (ESR-MP) and to compare the results with the gold standard Westergren method (ESR-W) in dogs. One hundred and nineteen K3-EDTA blood samples for complete blood count were randomly selected and assayed for ESR. The reference interval (RI) was established using the percentile method. The coefficient of variation (CV) in intra-assay and interassay precision of ESR-MP was calculated. The analytical sensitivity (Se), specificity (Sp), positive predictive values (PPVs), and negative predictive values (NPVs) were calculated. Agreement between ESR-MP and ESR-W was assessed with Pearson correlation coefficient (r), Cohen concordance test (K), Passing-Bablok regression, and Bland–Altman plots. Ten canine samples (8.4%) were ruled out because of flag-error by the MINIPET instrument (4.2%) or because they showed the diphasic pattern in ESR-W (4.2%). The canine RI of ESR-MP was 0–10 mm/h. Precision was excellent in intra-assay (CV = 0.02) and interassay (CV = 0.32). The analytical characteristics of ESR-MP in nonanemic samples were as follows: Se = 0.82, Sp = 0.95, PPV = 0.82, and NPV = 0.95. The accuracy of ESR-MP was better than ESR-W in nonanemic samples (r = 0.87; K = 0.77) and lower in anemic subjects (Hct <37%) (r = 0.76; K = 0.69). The Passing-Bablok regression showed the presence of systematic error and the absence of proportional error only in nonanemic blood samples. The Bland–Altman plots gave negative average values due to the difference in RIs and an agreement in both ESRs. The ESR-MP results can be obtained with the same K3-EDTA tubes used for the blood count, in shortcut time, and at reduced costs using the MINIPET device. These investigations highlight that ESR-MP could be useful in canine clinical settings.