title: Potential of a gonadotropin-releasing hormone vaccine to suppress musth in captive male Asian elephants (Elephas maximus).
abstract: Musth in adult bull elephants is a period of increased androgen concentrations ranging from a few weeks to several months. For captive elephant bull management, musth presents a serious challenge because of the aggressive behavior of musth bulls toward people and other elephants. Commercially available GnRH vaccines have been shown to suppress testicular function by interrupting the hypothalamo-pituitary-gonadal (HPG) axis in many species. The aim of this study was to test the efficacy of a GnRH vaccine in elephant bulls for suppressing the HPG axis and mitigating musth-related aggressive behavior. Five adult Asian elephant bulls (22-55 years old) were immunized with a GnRH vaccine starting with an initial injection 2-4 months before the predicted musth period, and followed by three boosters at approximately 4-week intervals. Blood samples were collected twice weekly for hormone and antibody titer analysis. An increase in GnRH antibody titers was observed in all bulls after the second or third booster, and titers remained elevated for 2-3 months after the final booster. Musth was attenuated and shortened in three bulls and postponed completely in two. We conclude that GnRH vaccination is capable of suppressing symptoms of musth in adult bull elephants. With appropriate timing, GnRH vaccination could be used to control or manage musth and aggressive behavior in captive elephant bulls. However, more work is needed to identify an optimal dose, booster interval, and vaccination schedule for complete suppression of testicular steroidogenesis.
authors.affiliation: Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand; Center of Excellence in Elephant Research and Education, Chiang Mai University, Chiang Mai 50200, Thailand. Electronic address: chaleamchat.s@cmu.ac.th.
authors.forename: Chaleamchat
authors.initials: C
authors.lastname: Somgird
authors.affiliation: Thai Elephant Conservation Center, National Elephant Institute, Forest Industry Organization, Lampang 52190, Thailand.
authors.forename: Pongpon
authors.initials: P
authors.lastname: Homkong
authors.affiliation: Center of Excellence in Elephant Research and Education, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Supaphen
authors.initials: S
authors.lastname: Sripiboon
authors.affiliation: Smithsonian Conservation Biology Institute, Smithsonian Institution, Front Royal, VA 22630, USA.
authors.forename: Janine L
authors.initials: JL
authors.lastname: Brown
authors.affiliation: Faculty of Veterinary Medicine, Utrecht University, Yalelaan 112, 3854 CM Utrecht, The Netherlands; Faculty of Veterinary Sciences, University of Pretoria, South Africa.
authors.forename: Tom A E
authors.initials: TA
authors.lastname: Stout
authors.affiliation: Faculty of Veterinary Medicine, Utrecht University, Yalelaan 112, 3854 CM Utrecht, The Netherlands.
authors.forename: Ben
authors.initials: B
authors.lastname: Colenbrander
authors.affiliation: Thai Elephant Conservation Center, National Elephant Institute, Forest Industry Organization, Lampang 52190, Thailand.
authors.forename: Sittidet
authors.initials: S
authors.lastname: Mahasawangkul
authors.affiliation: Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand; Center of Excellence in Elephant Research and Education, Chiang Mai University, Chiang Mai 50200, Thailand. Electronic address: chatchote.thitaram@cmu.ac.th.
authors.forename: Chatchote
authors.initials: C
authors.lastname: Thitaram
mesh_terms: D000374:Aggression / Q000187:drug effects / Q000502:physiology; D000818:Animals; D004606:Elephants / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology*; D008297:Male; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D014611:Vaccination / Q000662:veterinary
chemical_list: D007987:Gonadotropin-Releasing Hormone
keywords: Asian elephant (Elephas maximus); GnRH antibody titer; GnRH vaccine; LH; Musth; Testosterone