{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T04:30:40Z","timestamp":1791606640681,"version":"4.3.4"},"reference-count":88,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,5,23]],"date-time":"2022-05-23T00:00:00Z","timestamp":1653264000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Oregon Zoo"},{"name":"Portland State University Forbes-Lea Research Fund"},{"name":"Smithsonian Conservation Biology Institute"},{"name":"Oregon Zoo Foundation"},{"name":"North of England Zoological Society Chester Zoo"},{"name":"ABQ BioPark"},{"name":"Chiang Mai University"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The conservation of endangered species and sustainability of managed populations requires considerations to ensure the health and welfare of individuals. Male elephants experience a biological phenomenon called \u201cmusth\u201d, which is characterized by increased testosterone production, temporal gland secretion and urine dribbling, heightened aggression and sexual behavior, and therefore can pose unique challenges for human safety and animal welfare. This study characterized longitudinal (9 to 22 years) patterns of circulating testosterone and cortisol in relation to musth in four adult Asian elephant bulls spanning ages from 12 to 54 years. Age-related effects on musth activity and adrenal responses to social changes and clinical health events were also examined. All bulls exhibited regular annual musth cycles. Circulating cortisol covaried positively with testosterone and musth, highlighting intrinsic patterns that should be considered when evaluating the impact of social, health, and environmental changes on adrenal glucocorticoid activity. Except for an end-of-life cortisol increase in one bull, there was no clear evidence of chronically elevated cortisol secretion outside of musth in any individual. Testosterone decreased with age in sexually mature bulls, whereas age-related changes in cortisol varied across individuals, with the three older bulls showing the greatest rate of change during musth versus inter-musth periods. In contrast to physiological factors, there was no evidence of social factors, such as addition of a new male and death of male herdmates, impacting adrenal glucocorticoid activity in these bulls in the short term. Changes in cortisol were associated with treatment for Mycobacterium tuberculosis (M. tb) in two bulls, increasing after start of treatment and decreasing with cessation of treatment, but were not clearly associated with activation of disease. This study highlights the importance of longitudinal hormone monitoring to track changes in physiological function and responses to social, health, and environmental change in elephant bulls, which is important for making more informed decisions on how to manage male elephants under varying degrees of human care to ensure welfare and safety.<\/jats:p>","DOI":"10.3390\/ani12101332","type":"journal-article","created":{"date-parts":[[2022,5,23]],"date-time":"2022-05-23T22:57:22Z","timestamp":1653346642000},"page":"1332","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Characterization of Longitudinal Testosterone, Cortisol, and Musth in Male Asian Elephants (Elephas maximus), Effects of Aging, and Adrenal Responses to Social Changes and Health Events"],"prefix":"10.3390","volume":"12","author":[{"given":"Sharon S.","family":"Glaeser","sequence":"first","affiliation":[{"name":"Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6736-1183","authenticated-orcid":false,"given":"Katie L.","family":"Edwards","sequence":"additional","affiliation":[{"name":"North of England Zoological Society, Chester Zoo, Upton-by-Chester, Chester CH2 1EU, UK"},{"name":"Center for Species Survival, Smithsonian Conservation Biology Institute, Smithsonian National Zoological Park, Front Royal, VA 22630, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephen","family":"Paris","sequence":"additional","affiliation":[{"name":"Center for Species Survival, Smithsonian Conservation Biology Institute, Smithsonian National Zoological Park, Front Royal, VA 22630, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Candace","family":"Scarlata","sequence":"additional","affiliation":[{"name":"Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bob","family":"Lee","sequence":"additional","affiliation":[{"name":"Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA"},{"name":"ABQ BioPark, 903 10th St. SW, Albuquerque, NM 87102, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nadja","family":"Wielebnowski","sequence":"additional","affiliation":[{"name":"Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shawn","family":"Finnell","sequence":"additional","affiliation":[{"name":"Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA"},{"name":"White Oak Conservation, 581705 White Oak Road, Yulee, FL 32097, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chaleamchat","family":"Somgird","sequence":"additional","affiliation":[{"name":"Department of Companion Animal and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand"},{"name":"Center of Elephant and Wildlife Research, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3898-7755","authenticated-orcid":false,"given":"Janine L.","family":"Brown","sequence":"additional","affiliation":[{"name":"Center for Species Survival, Smithsonian Conservation Biology Institute, Smithsonian National Zoological Park, Front Royal, VA 22630, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1002\/zoo.1430090405","article-title":"Serum testosterone and musth in captive male African and Asian elephants","volume":"9","author":"Cooper","year":"1990","journal-title":"Zoo Biol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1163\/156853971X00087","article-title":"Reproductive behavior of the Asiatic elephant (Elephas maximus maximus L.)","volume":"38","author":"Eisenberg","year":"1971","journal-title":"Behaviour"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1530\/jrf.0.0290099","article-title":"Plasma testosterone levels in relation to musth and sexual activity in the male Asiatic elephant, Elephas maximus","volume":"29","author":"Jainudeen","year":"1972","journal-title":"J. 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