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. 2021 Sep;7(5):2032-2038.
doi: 10.1002/vms3.523. Epub 2021 May 12.

Cortisol levels in blood and hair of unanesthetized grizzly bears (Ursus arctos) following intravenous cosyntropin injection

Marc Cattet  1   2 , David M Janz  3   4 , Luciene Kapronczai  4 , Joy A Erlenbach  5 , Heiko T Jansen  6 , O Lynne Nelson  7 , Charles T Robbins  8 , Gordon B Stenhouse  9   10
Affiliations

Cortisol levels in blood and hair of unanesthetized grizzly bears (Ursus arctos) following intravenous cosyntropin injection

Marc Cattet et al. Vet Med Sci. 2021 Sep.

Abstract

Hair cortisol concentration (HCC) is being used increasingly to evaluate long-term stress in many mammalian species. Most of the cortisol is assumed to passively diffuse from circulating blood into hair follicles and gradually accumulate in growing hair. However, our research with free-ranging grizzly bears (Ursus arctos) suggests HCC increases significantly within several hours following capture, a time too brief to be explained by this mechanism alone. In this study with captive grizzly bears, we sought to determine if a brief spike in blood cortisol concentration, thus mimicking a single stressful event, would cause an increase in HCC over a 7-day period. To do this, we administered a single intravenous dose (5 μg/kg) of cosyntropin to three captive unanaesthetised adult female grizzly bears on two occasions, during April when hair growth was arrested and during August when hair was growing. In both trials, the cosyntropin caused a two-fold or greater increase in serum cortisol levels within 1 hr but did not appear to influence HCC at 1, 48, and 168 hr following cosyntropin administration. We conclude the cosyntropin-induced cortisol spike was likely insignificant when compared to the adrenocortical response that occurs in free-ranging bears when captured. We suggest further study with a larger sample of captive bears to evaluate the combined effects of anaesthesia and multiple doses of cosyntropin administered over several hours would better simulate the adrenocortical response of free-ranging grizzly bears during capture.

Keywords: Ursus arctos; cosyntropin challenge; grizzly bear; hair cortisol concentration (HCC); serum cortisol concentration.

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Figures

FIGURE 1
FIGURE 1
Serum cortisol concentrations of three adult female grizzly bears in April and August before and 1 hr following an intravenous injection of 5 μg/kg of cosyntropin. Note the lines for Kio and Peeka are overlapped in the August trial
FIGURE 2
FIGURE 2
Hair cortisol concentrations (HCC) of three adult female grizzly bears in April and August before and 1, 48, and 168 hr following an intravenous injection of 5 μg/kg of cosyntropin
FIGURE 3
FIGURE 3
Changes in hair cortisol concentrations (HCC) relative to baseline values of three adult female grizzly bears in April and August at 1, 48, and 168 hr following an intravenous injection of 5 μg/kg of cosyntropin
See this image and copyright information in PMC

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