The Winter Worries of Bats : Past and Present Perspectives on Winter Habitat and Management of Cave Hibernating Bats

Winter is a time of fascinating changes in biology for cave-hibernating bats, but it is also a time of vulnerability. Unsurprisingly, assessments of winter habitat for these mammals and how it can be managed have been a focus of many researchers involved with the North American Society for Bat Research over the last 50 years. Over this time, a paradigm shift has occurred in the way scientists think about factors driving selection of winter habitat, especially temperature. To illustrate this change, we review three hypotheses seeking to explain microclimate selection in cavernicolous bats. The first, which we call the “Colder is Better Hypothesis,” posits that bats should select cold microclimates that minimize energy expenditure. The “Hibernation Optimization Hypothesis” suggests that bats should select microclimates that reduce expression of torpor to balance energy conservation against non-energetic costs of hibernation. Finally, the “Thrifty Female Hypothesis” asserts that females should select colder microclimates than males to conserve energy for reproduction. We discuss these hypotheses and the shift from viewing hibernation as a phenomenon driven solely by the need to conserve energy in the context of hibernacula management in North America. We focus on both historical and recent conservation threats, most notably alteration of thermal regimes and the disease white-nose syndrome. We urge against returning to an over-simplified view of winter habitat selection in response to our current conservation challenges.Peer reviewe

Prediction of long-term outcome by measurement of serum concentration of cardiac troponins in critically ill dogs with systemic inflammation

BACKGROUND: Myocardial injury, detected by cardiac troponin I and T (cTnI and cTnT), has been associated with long‐term death in the noncardiac human intensive care unit (ICU). HYPOTHESIS: Presence of myocardial injury predicts 1‐year case fatality in critically ill dogs with systemic inflammation. ANIMALS: Thirty‐eight dogs with evidence of systemic inflammation and no primary cardiac disease. METHODS: Prospective cohort study. In dogs admitted to the ICU with evidence of systemic inflammation, blood samples were obtained at ICU admission for measurement of cTnI and cTnT, and cTnI was measured once daily during ICU hospitalization. Receiver operating characteristic (ROC) curves were used to examine prognostic capacity of admission cTnI, admission cTnT, and peak cTnI concentrations. RESULTS: One‐year case fatality rate was 47% (18/38 dogs). Admission cTnI concentrations were (median [range]) 0.48 [0.004–141.50] ng/mL, and peak cTnI concentrations were 1.21 [0.021–141.50] ng/mL. Admission cTnT concentrations were 15 [<13–3744] ng/L. For each marker, non‐survivors had significantly higher concentrations than survivors (P = .0082–.038). ROC analyses revealed areas under curves [95% CI] of 0.707 [0.537–0.843] for peak cTnI and 0.739 [0.571–0.867] for admission cTnT, respectively. At the optimal cut‐off, concentrations were 1.17 ng/mL (peak cTnI) and 23 ng/L (admission cTnT), sensitivities were 72% and 72%, and specificities were 70% and 80%, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: While peak cTnI and admission cTnT are significantly related to 1‐year case fatality in critically ill dogs with systemic inflammation, low sensitivities and specificities prevent their prediction of long‐term outcome in individual patients. Troponins might play a role in identification of dogs at long‐term risk of death