Quality of hematology and clinical chemistry results in laboratory and zoo nonhuman primates: Effects of the preanalytical phase. A review

Most errors in clinical pathology originate in the preanalytical phase, which includes all steps from the preparation of animals and equipment to the collection of the specimen and its management until analyzed. Blood is the most common specimen collected in nonhuman primates. Other specimens collected include urine, saliva, feces, and hair. The primary concern is the variability of blood hematology and biochemistry results due to sampling conditions with the effects of capture, restraint, and/or anesthesia. Housing and diet have fewer effects, with the exception of food restriction to reduce obesity. There has been less investigation regarding the impact of sampling conditions of nonblood specimens.

Improving the Quality of EDTA-treated Blood Specimens from Mice

Nonterminal blood sampling in laboratory mice is a very common procedure. With the goal of improving animal welfare, different sampling sites and methods have been compared but have not achieved a consensus. Moreover, most of these studies overlooked the quality of blood specimens collected. The main preanalytical concern with EDTA-treated blood specimens for hematology analyses is platelet aggregation, which is known to cause analytical errors. Our objective was to find a nonterminal blood sampling method with minimal adverse effects on mice and few or no platelet aggregates. We tested and compared 2 collection sites, 4 sampling methods, and 3 antithrombotic drugs in 80 C57BL6/j male and female mice by evaluating platelet aggregates on blood smears and platelet, WBC, and RBC counts. In addition, the blood collection process was carefully evaluated, and adverse effects were recorded. Platelet aggregation was lower in specimens collected from the jugular vein than from the facial vein, with no effect of the sampling device or the presence of an antithrombotic additive. Highly aggregated specimens were significantly associated with lower platelet counts, whereas aggregation had no effect on WBC or RBC counts. Adverse events during sampling were significantly associated with more numerous platelet aggregates. The jugular vein is thus a satisfactory sampling site in mice in terms of both animal welfare and low platelet aggregation. Using antithrombotic agents appears to be unnecessary, whereas improving sampling conditions remains a key requirement to ensure the quality of EDTA-treated blood specimens from mice.

Reference Values for Hematology, Plasma Biochemistry, Bone Marrow Cytology and Bone Histology of NOD.Cg-Prkdcscid Il2rgtm1Wjl/ SzJ Immunodeficient Mice

Highly immunodeficient NSG mice (NOD.Cg-Prkdc^scid Il2rg^tm1Wjl/SzJ) are commonly used as a models in preclinical studies for patient-derived engraftment. However, despite the frequency of their use, reference values for their clinical pathology markers have not been determined. In accordance with the American Society of Veterinary Clinical Pathology (ASVCP) recommendations, we established de novo reference values for hematologic and biochemical variables and evaluated bone marrow cytology and histology in forty 9-wk-old male and female NSG mice. Hematologic analyses were performed using 2 separate analyzers (IDEXX ProCyte Dx, Sysmex XT-2000iV) and biochemical values were measured using a Scil VetScan2. The primary hematologic characteristic seen in NSG mice was a very low white blood cell (WBC) count (below 1.6 10⁹/L). Lymphocyte and monocyte counts were respectively over- and under-estimated by the analyzers, as compared with manual counts, likely due to misidentification of the very low concentrations of these cell types by the analyzers. This analytical bias highlights the need for confirmatory microscopic observation of blood smears from these mice for WBC differential identification. Results for all other hematology and biochemistry variables were similar to those previously reported in inbred mice, except for MPV and an unexpectedly high glucose concentration (11.5 to 19.0 mmol/L), potentially due to the nonfasting status of the animals. The differential bone marrow cell count and Myeloid:Erythroid ratio (median 1.76) were also established. Megakaryocyte and adipocyte count differed significantly between the femoral diaphysis and metaphysis and between genders. These results provide a reliable resource of baseline data for hematologic variables for researchers monitoring graft rejection studies in NSG mice.

Evaluation of CTAD (citrate-theophylline-adenosine-dipyridamole) as a universal anticoagulant in dogs

CTAD (citrate-theophylline-adenosine-dipyridamole) has been shown to be an almost universal anticoagulant in human and feline medicine, allowing most hematology, coagulation, and biochemical analyses. Forty canine blood specimens were collected in CTAD, EDTA, heparin, and citrate for hematology, biochemistry, and coagulation analyses. CTAD partially limited platelet aggregation observed in EDTA blood smears. CTAD specimens gave similar and well-correlated results for most variables of a complete blood cell count, except for mean corpuscular volume, which was moderately higher, and mean corpuscular hemoglobin concentration, which was moderately lower in CTAD than in EDTA; reticulocyte and platelet indexes were poorly correlated. CTAD plasma gave similar results to citrate for fibrinogen, antithrombin, and D-dimers, and relatively similar results for prothrombin time, but activated partial thromboplastin time was poorly correlated. Triglycerides, cholesterol, glucose, total proteins, phosphate, iron, alanine aminotransferase, γ-glutamyl transferase, and lipase were similar and well correlated in CTAD and heparin plasmas. Urea, creatinine, albumin, alkaline phosphatase, amylase, and aspartate aminotransferase showed moderate-to-marked bias, but these variables could be measured in CTAD plasma if new reference intervals were determined. Creatine kinase activity, potassium, chloride, and total carbon dioxide measurements are not recommended in CTAD plasma. CTAD is a prospective candidate as an almost universal anticoagulant for routine hematology, some plasma coagulation, and many biochemistry variables in dogs. Definitive recommendations will require study of abnormal canine blood specimens.

Hematologic and Biochemical Biologic Variation in Laboratory Cats

The biologic variation associated with a clinical pathology result is important to consider before reference intervals (RI) are used. Most available RI are population-based RI, in which the analytical variability, interindividual variability, and intraindividual variability are confounded. In addition, when the intraindividual variability is considerably less than the interindividual variability, a population-based RI is insufficiently sensitive to detect changes in a subject over time. Here we determined the biologic variation and reference change value (RCV) of hematologic and biochemical variables in laboratory cats. Blood specimens from 14 (7 females and 7 males) overnight-fasted laboratory cats sampled 7 times (days 1, 2, 7, 14, 31, 42, and 100) were analyzed regarding hematology and biochemistry variables. For each variable, analytical, intraindividual, and interindividual coefficients of variation were estimated prior to calculation of the index of individuality and the RCV. RBC variables (count, Hgb, Hct, MCV, MCH, MCHC, and RBC distribution width) and 5 biochemical analytes (cholesterol, creatinine, triglycerides, ALP, and calcium) exhibited marked individuality, therefore indicating that subject-based reference intervals or RCV would be preferable when monitoring these variables in laboratory cats. Population-based RI were shown to be adequate for glucose and sodium, and both types of population and individual RI were similarly efficient for albumin, total protein, urea, ALT, AST, creatine kinase, chloride, carbon dioxide, iron, magnesium, inorganic phosphate, and potassium and reticulocyte, WBC, neutrophil, lymphocyte, monocyte, eosinophil, and platelet counts. The RCV determined in the present study provide a valuable tool for monitoring hematologic and biochemical variables in healthy laboratory cats.

Reference intervals, intraindividual and interindividual variability, and reference change values for hematologic variables in laboratory beagles

In research and development studies for human and veterinary medicine, relevant comparators for interpreting clinical pathology results are matched with concurrent control animals. However, reference intervals (RI) provide a comparator database and important aids for interpreting clinical pathology data, especially in laboratory beagle dogs. Furthermore, RI incorporate biologic variation, which includes analytical, intraindividual, and interindividual variation. No studies to date have established RI and studied the effect of biologic variation on hematologic variables in a large group of laboratory dogs. The purpose of this retrospective study was to establish hematologic RI for laboratory beagles according to international recommendations and estimate the effect of biologic variation in routinely measured hematologic analytes by using the databank at a pharmaceutical center. Blood specimens from 340 healthy beagles (age, 9 to 36 mo) were evaluated by using a flow-cytometry-based hematology analyzer. RI and their 90% confidence intervals were established by using a nonparametric method. Effects of sex, age, and weight were investigated. Weight had no effect on any analyte. RBC, Hgb, Hct, MCV, MCH, RBC distribution width, and platelet count increased with age, whereas WBC count decreased. The only clinically relevant effect of sex was observed for platelets, which were lower in male beagles than in female and warranted 2 different RI. The calculated index of individuality showed that population-based RI were appropriate for almost all hematologic analytes, as might be expected for a homogeneous group of laboratory beagles.

Changes in hematology measurements in healthy and diseased dog blood stored at room temperature for 24 and 48 hours using the XT-2000iV analyzer

BACKGROUND

Changes in canine hematology measurements may occur when analyses are delayed due to shipment of specimens to a laboratory.

OBJECTIVE

The purpose of this study was to report changes in hematologic variables in healthy and diseased canine blood measured with a Sysmex XT-2000iV during storage at room temperature for 24 and 48 hours.

METHODS

EDTA-K3 blood samples from 42 healthy and diseased dogs were measured on a Sysmex XT-2000iV analyzer within one hour of sampling, and after storage for 24 and 48 hours at room temperature in the dark.

RESULTS

Storage caused little or no change in RBC count, HGB concentration and MCH, while there was a moderate increase in HCT, MCV and reticulocytes count, and a moderate decrease in MCHC. Decreased platelet counts by impedance (PLT-I) and optical (PLT-O) measurements were associated with increased mean platelet volume (MPV), platelet-large cell ratio (P-LCR) and platelet distribution width (PDW), including a right shift in the platelet histogram and a dispersion of the platelet dot plot on the scattergram. The total and differential WBC count remained stable except for decreased monocyte counts. In the scatterplots, monocytes shifted into the lymphocyte population after 24 hours, and neutrophil population shifted to the right appearing in the eosinophil gate at 48 hours of storage. The disease status had only a small effect on storage-induced changes, and observed changes had no consequences for clinical decisions.

CONCLUSIONS

Blood storage at room temperature was accompanied by moderate variations in some hematologic variables, awareness of which helps in avoiding misinterpretations.

Validation of the Medonic CA620/530 Vet 20-microl microcapillary sampler system for hematology testing of feline blood

The aim of the current study was to compare feline hematologic variables in blood collected in microcapillary tubes (20 microl) and conventional blood tubes with the Medonic CA620/530 Vet in-house hematologic analyzer. A comparison of results obtained in 60 cats presented at the clinics of the veterinary school showed that the correlations between the 2 methods were 0.97 for white blood cell, 0.95 for red blood cell, and 0.93 for platelet counts; 0.92 for hemoglobin concentration; and 0.99 for mean corpuscular volume. No clinically relevant differences between the 2 blood sampling techniques were observed for any variable, which suggests that both techniques are interchangeable in cats. Moreover, microcapillary tubes would allow easier repeated sampling in the same cat and would likely be useful in other small species.