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-Prkdcscid Il2rgtm1Wjl/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.

Within-day and between-day variability of blood pressure measurement in healthy conscious Beagle dogs using a new oscillometric device.

OBJECTIVES: The main objective of this study was to determine the within- and between-day variability of blood pressure measurement in dogs using an oscillometric device, pet-MAP. ANIMALS, MATERIALS AND METHODS: Five healthy conscious adult Beagle dogs were used. The dogs were presented in a random order for examinations and the investigators were blinded to the dogs. Blood pressure was measured using a standardized procedure. Three investigators with the same level of experience, trained for 1 h with pet-MAP the day before starting the study, performed 480 blood pressure measurements in 5 healthy conscious dogs on two different days. RESULTS: The within- and between-day CVs for systolic blood pressure were 9.0-10.1% and 12.8-16.4%, respectively. The corresponding SD values were 14.7-16.6 mm Hg and 21.0-27.1 mm Hg respectively. For diastolic blood pressure, the within- and between-day CVs were 10.3-14.4% and 14.2-24.9% respectively. The corresponding SD values were 9.7-13.9 mm Hg and 13.0-24.0 mm Hg. CONCLUSIONS: The within- and between-day CVs for systolic blood pressure, measured with pet-MAP by investigators with a minimal period of training, seem to be acceptable in Beagle dogs without hypertension or hypotension. This study suggests that, using this device, one investigator can be replaced by another under the described circumstances.