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Hibernating bears: fat but healthy

Brown bears build up large fat reserves as a source of energy to fuel their hibernation. Despite the total physical inactivity, however, hibernating bears do not develop any cardiovascular disease during several months in winter. An international study led by Vetmeduni that was recently published in Scientific Reports shows that brown bears have effective protective mechanisms during hibernation to prevent damage to their blood plasma and muscles despite profound changes in their lipid metabolism and elevated lipid levels.

To investigate the mechanisms by which hibernators avoid the metabolic disorder known as atherogenic dyslipidemia during hibernation, the researchers assessed lipoprotein and cholesterol metabolisms of free‑ranging Scandinavian brown bears (Ursus arctos) by measuring lipoprotein sizes, subclasses and composition, triglyceride‑related plasma‑enzyme activities, and muscle lipid composition along with plasma‑levels of antioxidant capacities and inflammatory markers in bears during winter and summer. Their findings: “Although nearly all lipid levels were higher in the winter, a nearly one-third increase in activity of cholesteryl ester transfer protein, a key enzyme involved in cholesterol recycling based on futile cycles of re-esterification via lipoprotein metabolism, helped to stabilize the lipid composition of high‑density lipoproteins (HDL). The concentration of inflammatory metabolites declined in winter and correlated inversely with cardioprotective HDL2b‑proportions and HDL sizes that increased during hibernation,” says first author Sylvain Giroud, a wildlife and physiological ecologist at the Research Institute of Wildlife Ecology at Vetmeduni.

The article „Hibernating brown bears are protected against atherogenic dyslipidemia“ by Sylvain Giroud, Isabelle Chery, Mathilde Arrivé, Michel Prost, Julie Zumsteg, Dimitri Heintz, Alina L. Evans, Guillemette Gauquelin‑Koch, Jon M. Arnemo, Jon E. Swenson, Etienne Lefai, Fabrice Bertile, Chantal Simon, and Stéphane Blanc was published in Scientific Reports veröffentlicht.

Vetmeduni press release


Wild boars don't like hot weather either

Typically, large ungulates show a single seasonal peak of heart rate, a proxy of energy expenditure, in early summer. Different to other large ungulates, wild boar females had peak heart rates early in the year (around early April), which likely indicates high costs of reproduction. This peak was followed by a trough over summer and a secondary summit in autumn/early winter, which coincided with the mast seeding of oak trees and the mating season. Wild boars counteracted the effects of cold temperatures by decreasing subcutaneous body temperature by peripheral vasoconstriction. They also passively gained solar radiation energy by basking in the sun. 

However, the shape of the seasonal rhythm in heart rate indicates that it was apparently not primarily caused by thermoregulatory costs but by the costs of reproduction. Wild boar farrow early in the year, visible in high HRs and sudden changes in intraperitoneal body temperature of females. Arguably, a prerequisite for this early reproduction as well as for high energy metabolism over winter is the broad variety of food consumed by this species, i.e., the omnivorous lifestyle.

Extremely warm and dry summers, as experienced during the study years (2017, 2018), may increasingly become a bottleneck for food intake of wild boar.

The article "Atypical for northern ungulates, energy metabolism is lowest during summer in female wild boars (Sus scrofa)" von Thomas Ruf, Sebastian G. Vetter, Johanna Painer, Gabrielle Stalder & Claudia Bieber ist im September 2021 in der Zeitschrift Scientific Reports erschienen.


Important state award for Walter Arnold

Professor Walter Arnold, long-time head of the Research Institute for Wildlife Ecology (FIWI) at the University of Veterinary Medicine, Vienna, received the Great Silver Medal for Services to the Republic of Austria. It is one of the highest state awards and was presented during his retirement ceremony on August 27, 2021.

For more than 25 years, Professor Arnold was responsible for the Research Institute for Wildlife Ecology located on Wilhelminenberg, which enjoys a high reputation beyond national borders. He expanded the interdisciplinary research approach and the range of methods of FIWI, putting the focus on the needs and behavior of wild animals in the context of ecology. The research results obtained in this way form an important scientific basis for effective nature, species and environmental protection.

More info (in German) on the website of the Vetmeduni



Little snoozers: Common dormice in portrait

The small, nimble climber has thick, gray fur, large dark button eyes and small ears. It is nocturnal and lives up to its name: the dormouse is the world record holder when it comes to hibernation. In 2021 the rodent was named Animal of the Year by the Austrian Nature Conservation Union. At the Vetmeduni, researchers are devoting themselves to the dormouse with the help of various research projects. At the Research Institute for Wildlife Science and Ecology, Claudia Bieber heads some current research projects on the life strategies of the dormouse.

Profile and interesting facts about the dormouse

  • ORDER: Rodents (Rodentia)
  • FAMILY: Dormouse (Gliridae)
  • GENUS: Glis
  • TYPE: dormouse (lat .: glis glis)
  • BODY LENGTH: approx. 14 cm
  • TAIL LENGTH: approx. 11 cm
  • WEIGHT: approx. 100 g in early summer
  • AGE: up to 14 years
  • DISTRIBUTION AREAS: Continental Europe, Asia Minor, Caucasus to northwestern Iran


Video: dormice performing a test task in the labyrinth (Video: Jan Müller, Tabea Lammert/FIWI)

More info on the Vetmeduni website



MERS-CoV induces similar immune response as with SARS-CoV-2

MERS-CoV, a betacoronavirus transmitted by dromedaries, is significantly more lethal than SARS-CoV-2, with a mortality rate in humans of up to 35%. A recently published international study led by Pamela Burger from the Research Institute of Wildlife Ecology of the Vetmeduni Vienna suggests that the immune response to MERS-CoV and SARS-CoV-2 is similar in infected individuals, whether human or dromedary. According to the researchers, further work is now urgently needed to better understand MERS-CoV disease dynamics in both dromedaries and humans.

The article "Innate and Adaptive Immune Genes Associated with MERS-CoV Infection in Dromedaries“ by Sara Lado, Jean P. Elbers, Martin Plasil, Tom Loney, Pia Weidinger, Jeremy V. Camp, Jolanta Kolodziejek, Jan Futas, Dafalla A. Kannan, Pablo Orozco-terWengel, Petr Horin, Norbert Nowotny and Pamela A. Burger was published in Cells.