*The tail-tale of stress: An exploratory analysis of cortisol levels in the
tail-hair of captive Asian elephantsSanjeeta Sharma Pokhare, Hiroki Yoneda,
Moe Yanagi, Raman Sukumar & Kodzue KinoshitaPeerJJanuary 4, 2021 Abstract *
Background
Assessment of physiological states by measuring biomarkers, such as
cortisol, has significantly contributed to the monitoring of health,
welfare and management of animals. Immunoreactive cortisol in hair (hC) has
been used widely for deciphering ‘stressful’ past-events in various wild
and captive animals. However, no such studies have been done in long-lived
mammals.
Methods
In this first exploratory study in elephants, we assessed (i) tail-hair
growth rate (TGR) and (ii) hC levels in tail-hair samples from six captive
Asian elephants from two zoos in Japan for comparing hC levels with
zoo-keepers’ records of distinct biological events over a c.0.5–2.0-year
period. Tail-hair samples were cut into segments (based on monthly growth
rate), pulverized or minced and a validated cortisol enzyme-immunoassay
employed to measure hC levels.
Results
When the hC levels of all individuals were compared with the keepers’
records, a posteriori, most of the high hC levels were found to be
associated with ‘stressful’ or distinct behavioural events such as
pathological (anaemia, colic infection, skin infection, oral sores),
psychosocial (reluctance in entering the enclosure, presence of a calf) and
husbandry practice-related (contact trials/ space sharing) conditions,
indicating that tail-hair indeed can be a potential ‘retrospective’
calendar of physiological health of an animal.
Conclusions
Our observations open up the possibility of using the tail-hair as an
alternative matrix to reconstruct the physiological history of elephants.
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PAPER WEB LINKhttps://peerj.com/articles/10445/
https://peerj.com/articles/10445/