Variability of hematological blood parameters and establishment of reference intervals in preclinical studies. Part 1: rodents and rabbits

Hematological analysis or a general blood test aimed at assessing the qualitative and quantitative composition of blood allows you to take into account a wide range of indicators. This is one of the most basic and commonly used methods for monitoring the health of laboratory animals and evaluating the progress of an experiment. With its help, you can get a characteristic of all the shaped elements of the blood: erythrocytes, leukocytes and platelets, evaluate their percentage, shape and appearance, detect pathological forms of cells, progenitor cells or various inclusions. This type of analysis can help detect early changes in the body’s health status and identify conditions such as anemia, polycythemia, thrombocytopenia, and leukopenia, which can be symptoms of disease or independent pathologies. That is why it is necessary to have reference intervals of hematological blood parameters of healthy laboratory animals in each scientific center, taking into account critical preanalytical, analytical and postanalytical features. The aim of this study was to determine the reference ranges of hematological blood parameters for both male and female mice, gerbils, hamsters, rats, guinea pigs, and rabbits, which are commonly used as test models in biomedical research. The age of all animals corresponded to the range of puberty, males and non-pregnant and unborn females were included in the study, without taking into account the phase of the menstrual cycle. The data used in this work were obtained from intact animals during the time period January-June of 2024 at research and manufacturing company “Home оf Pharmacy”. The work was divided into two stages: assessing indicators on a hematology analyzer and calculating the leukocyte formula through microscopic analysis. In the whole blood of animals, such indicators were recorded using a hematological analyzer as: total number of erythrocytes, hematocrit, hemoglobin concentration, average volume of erythrocytes in the total volume of the sample, average hemoglobin content in erythrocytes, average concentration of hemoglobin in erythrocytes, total number of platelets, total number of leukocytes, number of lymphocytes and granulocytes. When calculating the leukocyte formula, such indicators as the content of neutrophils, eosinophils, monocytes, basophils and lymphocytes were recorded. When comparing the obtained intervals with reference values from literary sources, it was shown that, in general, the ranges of the considered indicators are similar, but there are also differences. The greatest differences were associated with the number of erythrocytes, platelets, monocytes, lymphocytes, neutrophils and hemoglobin concentration. The reference intervals calculated during the study can be a useful tool for monitoring the health status of laboratory animals during preclinical experiments.