Storage-associated changes in the bovine hemogram with the ADVIA 120 hematology analyzer

BVDV permissiveness and lack of expression of co-stimulatory molecules on PBMCs from calves pre-infected with BVDV

Bovine viral diarrhea virus (BVDV) has been detected in peripheral blood mononuclear cells (PBMCs) of immunocompetent animals, not being clear whether the development of a specific humoral immune response can prevent BVDV infection. The aim of this study was to evaluate the ability of non-cytopathic BVDV to replicate and produce infectious virus in PBMCs from calves pre-infected with BVDV and to elucidate the immunomodulatory effect of BVDV on these cells in an in vitro model. Quantification of virus was by quantitative PCR, while its replicative capacity and shedding into the extracellular environment was evaluated by viral titration. Apoptosis was assessed by flow cytometry analysis of annexin V and propidium iodide, and by expression of caspase-3/7. Flow cytometry was used to analyze the expression of CD14/CD11b/CD80, CD4/CD8/CD25, MHC-I/MHC-II and B-B2 markers. Our results showed that PBMCs from cattle naturally infected with BVDV were more susceptible to in vitro BVDV infection and showed a more severe apoptosis response than those from naïve animals. Non-cytopathic BVDV in vitro infection also resulted in a lack of effect in the expression of antigen presentation surface markers. All these findings could be related to the immunosuppressive capacity of BVDV and the susceptibility of cattle to this infection.

Effect of time and storage on toxic or pseudo-toxic change in canine neutrophils

BACKGROUND

The presence of toxic change in neutrophils is frequently used as a biomarker of inflammation in dogs.

OBJECTIVE

We aimed to evaluate the effect of time and storage on toxic change in canine neutrophils.

METHODS

One hundred and fifty microliters of EDTA blood were obtained from eight dogs with no toxic neutrophil changes observed on fresh blood smears (T0). Blood was stored at room temperature (RT), in a box with an icepack (ICE), and at 4°C. For each storage condition, smears were prepared 2 (T2), 4 (T4), 8 (T8), and 24 (T24) hours post blood draw. Smears were randomized, and each smear was evaluated for the presence of toxic neutrophil change.

RESULTS

A statistically significant effect of time and storage on the presence of toxic neutrophil change was observed. Compared with T0, the number of neutrophils containing Döhle bodies was significantly higher at T8 and T24 for the RT (P < 0.0001) and ICE (P < 0.0001) samples and at T24 for 4°C samples (P < 0.0001). Additionally, smears were falsely classified as having 1+ toxic change in 0/8 (T2), 1/8 (T4), 3/8 (T8), and 8/8 (T24) for RT samples; 0/8 (T2 and T4), 2/8 (T8), and 5/7 (T24) smears for ICE samples; and 0/8 (T2, T4, and T8) and 2/8 (T24) for 4°C samples.

CONCLUSIONS

Smears can be falsely classified as having neutrophils with toxic change as early as 4 hours post blood draw in samples stored at RT, 8 hours when stored with icepacks, and 24 hours when stored at 4°C. Canine blood smears should be prepared and evaluated for toxic neutrophil change as early as possible.

Validation of an automated cell counter to determine leukocyte differential counts in neonatal Holstein calves

Recent advances in the understanding of risk factors and biomarkers in calves entering rearing facilities show promise for identifying high-risk calves on arrival at veal and dairy beef operations. Rapid automated leukocyte differential cell counts may be a good addition for augmenting or refining calf risk identification on-farm. The objective of this study was to validate an automated leukocyte cell counter, the QScout BLD test (Advanced Animal Diagnostics, Morrisville, NC), for its ability to determine leukocyte differential cell counts in neonatal Holstein calves. From June to July 2018, blood samples collected in EDTA anticoagulant from 235 calves upon arrival at an independent veal research facility in Ontario, Canada, were evaluated using the QScout BLD test and manually by microscopy. We compared these leukocyte differential counts using Lin's concordance correlation coefficient (ρ) and found very good agreement between tests for neutrophil counts (ρ = 0.83); fair agreement for lymphocyte counts (ρ = 0.32); fair agreement for the ratio of neutrophils to lymphocytes (ρ = 0.36); slight agreement for monocyte counts (ρ = 0.14); and slight agreement for eosinophil counts (ρ = 0.20). We further examined test results to determine if they differed in their classification of samples as being above, within, or below reported 95% reference intervals for neonatal Holstein calves. Classification between tests resulted in very good agreement for neutrophils and lymphocytes, with only 4.2% and 5.8% disagreement in classification, respectively. We observed moderate agreement for monocytes, with 23.3% classified differently, and poor agreement for eosinophils, with 70.3% classified differently. Further study is required to determine the role of leukocyte profiling in the risk assessment of calves arriving at calf-rearing facilities.

Hematology as a diagnostic tool in bovine medicine

The objective of the current review is to provide the reader with an overview of the bovine hematological profile. Sample collection, bovine reference ranges, and cattle-specific characteristics of erythrocyte, leukocyte, and platelet parameters are reviewed. Furthermore, diseases associated with abnormalities in the complete blood cell count of cattle are discussed.