An experimental test of energy and electrolyte supplementation as a mitigation strategy for white-nose syndrome

Abstract

Fungi are increasingly recognised as harmful pathogens of wildlife. White-nose syndrome (WNS) is a fungal disease that has killed millions of hibernating bats in North America. High mortality has driven research to identify management strategies for the disease. Increased energy expenditure and fat depletion, as well as fluid loss, hypotonic dehydration and electrolyte depletion appear to be key aspects of WNS pathophysiology. Bats with WNS spend energy too quickly and also lose fluids containing water and electrolytes from lesions on exposed skin surfaces. During periodic arousals, bats often drink water but, in most of the WNS-affected area, food is not available during winter and, therefore, they cannot maintain energy balance or replace lost electrolytes. Therefore, providing a liquid caloric/electrolyte/nutrient supplement could be useful for treating WNS. We studied captive, hibernating little brown bats (Myotis lucifugus) to test whether providing supplemental energy and electrolytes (a 1:1 dilution of unflavoured Pedialyte) to hibernating bats could reduce severity of WNS symptoms and increase survival. Infected bats in the Pedialyte-supplemented group generally avoided the Pedialyte and preferentially drank plain water. We did not observe any differences in survival, arousal frequency or blood chemistry, but bats in the Pedialyte-supplemented group had higher fungal load and more UV fluorescence than the control group that was only provided with water. Supplemental electrolytes would be an attractive management strategy because of their low cost and logistic feasibility but our results suggest this approach would be ineffective. However, it could be useful to conduct preference experiments with multiple dilutions and/or flavours of electrolyte solution. Although they did not prefer Pedialyte in our experiment, bats in the hand readily drink it and electrolyte supplementation remains an important tool for rehabilitation of captive bats recovering from WNS and other causes of dehydration.