Leukocyte Coping Capacity: An Integrative Parameter for Wildlife Welfare Within Conservation Interventions

Abstract

Wildlife management, conservation interventions and wildlife research programs often involve capture, manipulation and transport of wild animals. Widespread empirical evidence across various vertebrate taxa shows that handling wildlife generally induces a severe stress response resulting in increased stress levels. The inability of individuals to appropriately respond to rapidly changing environmental conditions during and after manipulations may have deleterious and long-lasting implications on animal welfare. Therefore, mitigating stress responses in the frame of conservation interventions is a key animal welfare factor. However, we have a poor understanding of the metrics to adequately assess and monitor the dynamic physiological changes that animals undergo when subjected to stressful procedures in wild or captive conditions. A growing number of studies provide good evidence for reciprocal interactions between immune processes and stress. Here, we review the existing literature on a relatively new technique—Leukocyte Coping Capacity (LCC), a proxy for stress quantifying oxygen radical production by leukocytes. We discuss the strength and weaknesses of this immunological approach to evaluate stress, the individual capacity to cope with stress and the resulting potential implications for animal welfare. Additionally we present new data on LCC in captive roe deer ( Capreolus capreolus ) under long-time anesthesia and free-ranging Asiatic wild asses (Kulan; Equus hemionus kulan ) were LCC was used to assess stress levels in animals captured for a reintroduction project.

Leukocyte coping capacity as a complementary stress metric in migrating birds

“…For the first time, we report a physiological response to restraint stress during the migratory period using LCC, where LCC levels significantly decreased with sampling time. In general and independently of life-history stages, low LCC levels and no recovery or a decrease in LCC within 30 min after a short-term stress event suggest high-stress levels and diminished capacity of the organism to effectively cope with and recover from stress (Huber et al 2019;McLaren et al 2003). The decline in LCC of the current study in all individuals is remarkable since captive house sparrows showed an increase in LCC, interpreted as a partial restoration of the capacity to cope with repeated or novel stress (Huber et al 2017).…”

“…Other physiological pathways, such as the endocrineimmune interface may provide additional insights into stress associated trade-offs and biological costs but are rarely studied. Based on the observation that leukocytes of stressed individuals have a reduced capacity to produce reactive oxygen species (ROS) in response to a secondary (chemical) external stimulus, several studies on mammals have used a method called leukocyte coping capacity (LCC; leukocyte ROS production; McLaren et al 2003) as a proxy for stress (reviewed by Huber et al 2019). Recently, we showed in captive House Sparrows (Passer domesticus) that the immunological tool LCC may provide a more integrative perspective on the effects of stress rather than being just one of its constituent mediators (Huber et al 2017).…”

“The stressed bird in the hand”: Influence of sampling design on the physiological stress response in a free-living songbird

“…LCC has been suggested as a reliable and sensitive tool to measure stress in mammals and birds and has been successfully applied to assess psychological stress in humans (Mian and MacDonald, 2010; Shelton-Rayner et al, 2012). In respect to the existing literature, a decrease in the LCC response, or a lack of recovery respectively, is an indicator for high stress levels and a reduced capacity to cope with and/or recover from a stress event (Huber et al, 2019; McLaren et al, 2003). For instance, in captive house sparrows ( Passer domesticus ), leaving the birds undisturbed for 30 min in a cotton bag was sufficient to allow individuals to recover from capture stress in winter, reflecting in an increase of the measured LCC response (Huber et al, 2017).…”

“…In the course of a stress response, the glucocorticoid-, α- and β-adrenoceptors of heterophil granulocytes are activated and an “oxidative burst”, is triggered, leading to the release of superoxide free radicals and the production of reactive oxygen species (ROS) (Frolov et al, 2006; Ronchetti et al, 2018). This reaction can be simulated under experimental conditions and measured in real-time via chemiluminescence from whole blood (Huber et al, 2020; Huber et al, 2019).…”

COVID-19 and the Curse of Piecemeal Perspectives

“…These activities induce stress, injury, sickness, and compromise immune systems. The multiple stressors inhibit animal immune responses and allow for enhanced shedding of pathogens ( 15 ). Stress also leads to increased excretion of saliva and voiding of urine and feces, all of which facilitate the shedding of viruses.…”