Circadian Variation of Peripheral Blood Cells in Horses Maintained in Different Environmental and Management Conditions

Abstract

The aim of our study was to analyze circadian rhythm of the hematological profile of horses housed in a loose box and paddock during the different seasons (spring, summer, autumn, and winter). Blood samples were performed every 4 h for 48 consecutive hours. Red blood cells (RBCs), hemoglobin (HGB), hematocrit (HCT), white blood cells (WBCs), platelets (PLTs), and leukocyte subpopulations (neutrophils, basophils, eosinophils, lymphocytes, and monocytes) were analyzed, and, at the same time, environmental conditions were recorded. A statistically significant effect of housing conditions (p < 0.0001) was observed on all hematological values except for WBC during winter and for neutrophils (p < 0.0001) during spring and autumn. A statistically significant effect of season (p < 0.0001) was found for RBC, HCT, and PLT and for all leukocyte cells (p < 0.0001) except for basophils. The single Cosinor method revealed a daily rhythm of hematological parameters during spring in both groups, and a daily rhythm for lymphocytes and neutrophils was observed during spring and summer in horses kept in a loose box and during winter in horses housed in a paddock. Our results revealed that the response of the immune system is regulated by circadian physiology. Knowledge of the periodic temporal structure of mammals should be considered when evaluating animals’ adaptation to temporizations imposed by the environment.

The effect of solarium light therapy on selected biological and biochemical parameters of peripheral blood in young and old horses

“…Cold environment stabilises mentioned indices without affecting the overall cell count because blood cells are already in equilibrium [51]. The present study was conducted in winter; therefore, main blood parameters were probably stabilised.…”

Eye Temperature Measured with Infrared Thermography to Assess Stress Responses to Road Transport in Horses

“…The reliable measurement of physiological variations in athletic horses is important both for animal welfare and optimal sport performance [10]. Optimal physiological status evaluation using various invasive techniques, such as blood sampling and cortisol measurement, thermal microchips, tympanic thermometers and rumen boluses, has been well documented in mammals [11][12][13][14]. Research interest has expanded to the use of minimally invasive methodologies to evaluate physiological changes in domestic animals, such as infrared thermography (IRT), which is a non-contact temperature measurement method offering several advantages over other temperature measurement methods used in veterinary medicine [15][16][17][18].…”