Acute Thermal and Stress Response in Moose to Chemical Immobilization

Abstract

Management and research of moose (Alces alces) in Alaska, USA, often require chemical immobilization; however, moose may be prone to capture‐induced hyperthermia while immobilized. We chemically immobilized moose with carfentanil citrate and xylazine hydrochloride to measure rump fat depth, collect blood and fecal samples, and to deploy modified vaginal implant transmitters and global positioning system (GPS)‐collars for recording body temperature and movement during and after the chemical immobilization. We predicted wild moose pursued and captured from a helicopter would have elevated body temperature at time of capture, whereas body temperature would remain stable in hand‐raised captive moose not pursued and only hand‐injected for immobilization. Additionally, we expected post‐capture body temperature would be a function of activity, time immobilized, and ambient temperature. As predicted, body temperature of wild moose was elevated 1 hour after capture (38.9°C, 95% CI = 38.7–39.1°C) but returned to baseline levels within 3 hours (38.0°C, 95% CI = 37.9–38.1°C); however, body temperatures then rose above baseline levels and remained elevated 12–48 hours post‐capture when movement rates were also elevated. Body temperatures in captive moose were not elevated 1‐hour post‐immobilization (37.9°C, 95% CI = 37.8–38.0°C). Body temperatures of wild moose were positively related to cortisol levels at time of capture. Two moose that died after immobilization had initial body temperatures similar to other immobilized moose; however, their body temperature began to rise at 17 hours and 40 hours post‐immobilization. Our study provides evidence that chemical immobilization affects body temperature and movement of wild moose up to 48 hours after capture, possibly as a result of renarcotization from carfentanil citrate. With advancements in technology, we recommend fine‐scale GPS data (<1‐hr fix rates) and continuous body temperature be evaluated to detect evidence of renarcotization during and after opioid‐based captures of northern ungulates. © 2020 The Wildlife Society.

Helicopter‐Based Chemical Immobilization of Mountain Goats in Coastal Alaska

“…Increasing trends in rectal temperature during immobilization might also be indicative of body temperatures that continue to increase post release, as has been described in other ungulates immobilized with potent opioids (Meyer et al 2008, Thompson et al 2020). Increasing body temperatures post‐release are an important consideration, particularly for mountain goats, because released individuals often exert themselves moving uphill and climbing into steep terrain after release.…”

“…Mitigation of hyperthermia in our study involved abbreviated handling, exposure of the skin of the axilla and groin region to cold water or snow, whenever available, as well as administration of the nonsteroidal, anti‐inflammatory flunixin meglumine (50 mg/ml) via intramuscular injection (100–250 mg depending on body mass); this treatment can have antipyretic effects and may improve hemodynamics. Administration of respiratory stimulants such as doxapram, which can assist in reduction or stabilization of body temperature (Thompson et al 2020), was also used in some instances. Nonetheless, despite implementation of such mitigative measures, 9.1% (2/22) of animals that were darted twice died (due to hyperthermia or suspected capture myopathy), a frequency that was 5.6 times higher than for animals that were immobilized with a single dart (1.6%, 8/486).…”

“…However, certain considerations still apply and dose adjustments may be necessary. In moose, for example, capture stress (indexed by glucocorticoid responses) and percent body fat play an important role in determining appropriate doses of carfentanil in both helicopter‐based free‐ranging and ground‐based semi‐captive capture settings (Thompson et al 2020). In mountain goats, females appeared to exhibit heightened intensity of activity during helicopter pursuit compared to males, even though gender‐specific chase times were roughly equivalent.…”

Helicopter‐based immobilization of moose using butorphanol–azaperone–medetomidine

“…General wildlife handling protocols recommend corrective action in the event of sustained (>2 minutes) low oxygen saturation (<70%; Kreeger and Arnemo 2012). A respiratory stimulant, doxapram hydrochloride, can be used with supplemental oxygen to treat respiratory depression (Thompson et al 2020) or in combination with chest compressions to treat respiratory arrest (Arnemo et al 2003). Appropriate interventions to treat low oxygen saturation can protect against organ damage, capture myopathy (Kreeger and Arnemo 2012), and post-capture hyperthermia (Thompson et al 2020).…”

Using Piecewise Regression to Identify Biological Phenomena in Biotelemetry Datasets

“…Effects of capture, handling, and transmitter deployment are not well understood for many wildlife species, especially in the short-term period immediately post-capture. Efforts to quantify animal response have predominantly focused on the impacts of the transmitter itself (i.e., the weight and aerodynamics of the unit, usually in birds: Evans et al, 2020) or on the physiological effects from chemical immobilization (typically in large mammals: Barron et al, 2010; Brivio et al, 2015; Thompson et al, 2020). Most researchers have sought to quantify effects on vital rates, such as survival and fecundity (Casas et al, 2015; DelGiudice et al, 2005; Lameris & Kleyheeg, 2017), or short-term ethological responses such as changes in the time spent grooming (Kölzsch et al, 2016; Rachlow et al, 2014).…”