Use of gonadotrophin releasing hormone (GnRH) vaccines for behavioural and reproductive control in managed Asian elephant Elephas maximus and African elephant Loxodonta africana populations

Abstract

Because of their size and reproductive anatomy, surgical castration is not a practical option in adult elephants. However, similar to other species in human care, the effects of gonadectomy are desired in specific situations. This may be for contraceptive purposes, or for behavioural or veterinary management of elephants in human care or wild elephants managed in small reserves. Research into non‐surgical contraceptive measures for wild and domestic animals has resulted in an array of hormonal and immunological options to downregulate gonadal function. Driven by the production‐animal industry, commercial gonadotrophin releasing hormone (GnRH) vaccines are readily and cheaply available. This immunocontraceptive is effective in both males and females as it inhibits gonadotrophic hormone release and, thus, downstream stimulation of testicles and ovaries. Here, available studies from the past 10 years on the GnRH vaccine application in male and female elephants are reviewed. Furthermore, we add our own experience gathered from the treatment of male African elephants Loxodonta africana and female Asian elephants Elephas maximus in human care. The GnRH vaccine offers a viable approach for various management purposes. It should be noted that the GnRH vaccine was not primarily designed as a reversible contraceptive. Therefore, its use must be well justified on an individual basis and the effects closely monitored.

Surgical contraception of free‐ranging female capybaras: Description and comparison of open and minimally invasive techniques

“…4 It is territorial and forms family groups that have a strong social hierarchy. 5 In contrast with other wild animals, [6][7][8][9] there are a few recent reports on hormone therapy use 10 or immunocontraceptive methods 11 in capybaras. However, these studies have only addressed males.…”

Of Elephants and Other Mammals: A Comparative Review of Reproductive Tumors and Potential Impact on Conservation

“…Leiomyomas will not be suppressed in females that do cycle, but may in females that cease folliculogenesis. Therefore, GnRH vaccines may be a better choice when the goal is to suppress ovarian activity [ 132 ], because GnRH vaccines reduce gonadal hormone levels, including luteinizing hormone [ 7 ]. In some cases (Asian and African elephants), GnRH vaccines prevented cycling and even decreased or resolved uterine leiomyomas [ 132 , 133 , 134 ].…”

“…Therefore, GnRH vaccines may be a better choice when the goal is to suppress ovarian activity [ 132 ], because GnRH vaccines reduce gonadal hormone levels, including luteinizing hormone [ 7 ]. In some cases (Asian and African elephants), GnRH vaccines prevented cycling and even decreased or resolved uterine leiomyomas [ 132 , 133 , 134 ]. However, in other cases (African elephant) GnRH vaccine did not induce anestrus [ 135 ].…”

Review of the management of the Asian elephant Elephas maximus EEP: current challenges and future solutions

“…Such use of contraceptives could contribute to maintaining the desired interbirth interval of 7 years. In recent decades, only a limited number of reproductive‐control methods that are appropriate for elephants have been described in the literature; for example, the immunocontraception vaccine derived from porcine zona pellucida and GnRH vaccines (Boedeker et al , ; Druce et al , ; Lueders et al , ). Other methods, such as the use of oral and long‐acting injectable progestogens, need to be investigated.…”