Seasonal variation in haematological and biochemical variables in free-ranging subadult brown bears (Ursus arctos) in Sweden

• Published in: BMC Veterinary Research
• Main Authors: Græsli, Anne Randi, Evans, Alina L., Fahlman, Åsa, Bertelsen, Mads F., Blanc, Stéphane, Arnemo, Jon M.
• Other Authors: Department of Forestry and Wildlife Management, Hedmark University College, Center for Zoo and Wild Animal Health, Copenhagen Zoo, Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Département Ecologie, Physiologie et Ethologie (DEPE-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Department of Wildlife, Fish and Environmental Studies
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Brown bear; Ursus arctos; Haematology; Biochemistry; Seasonality; [SDE]Environmental Sciences
• Online Access: https://hal.science/hal-01298692; https://doi.org/10.1186/s12917-015-0615-2

International audience Background: Free-ranging brown bears exhibit highly contrasting physiological states throughout the year.They hibernate 6 months of the year, experiencing a decrease in body temperature, heart rate, respiratoryrate and metabolism. An increase in food consumption and the resulting weight gain (mostly through fatstorage) prior to hibernation are also part of the brown bear’s annual cycle. Due to these physiological changes,haematological and biochemical variables vary dramatically throughout the year. Seasonal changes in 12haematological and 34 biochemical variables were evaluated in blood samples collected from 40 free-ranging subadultbrown bears (22 females, 18 males) immobilised in Sweden in winter (February-March), spring (April-May), andsummer (June).Results: Higher levels of haemoglobin, haematocrit and red blood cell count, and a lower white blood cellcount and mean cell volume was found during hibernation than in spring and summer. Lower values of theenzymes; aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (AP), γ-glutamyltranspeptidase (GGT), glutamate dehydrogenase (GD) and amylase, and increased values of β-hydroxybutyrate(β-HBA) and blood lipids; triglycerides, cholesterol and free fatty acids, were present during hibernationcompared to spring and summer.Conclusions: This study documents significant shifts in haematological and biochemical variables in samplescollected from brown bears anaesthetised in winter (February-March) compared to in spring and summer(April-June), reflecting the lowered metabolic, renal and hepatic activity during hibernation. Lower values ofenzymes and higher values of blood lipids during hibernation, likely reflect a lipid-based metabolism.