EFFECTS OF A GONADOTROPIN-RELEASING HORMONE VACCINE ON OVARIAN CYCLICITY AND UTERINE MORPHOLOGY OF AN ASIAN ELEPHANT (ELEPHAS MAXIMUS)

Abstract

This report describes the successful use of a gonadotropin-releasing hormone (GnRH) vaccine to suppress ovarian steroidogenic activity and to treat hemorrhage and anemia associated with reproductive tract pathology in a 59-year-old Asian elephant (Elephas maximus). The Repro-BLOCt GnRH vaccine was administered subcutaneously as a series of 4 boosters of increasing dose from 3 to 30 mg of recombinant ovalbumin-GnRH fusion protein given at variable intervals after initial vaccination with 3 mg protein. Efficacy was confirmed over a year after initial vaccination based on complete ovarian cycle suppression determined by serum progestagen analyses. Estrous cycle suppression was associated with a significant increase in GnRH antibody binding and subsequent decrease in serum luteinizing hormone and follicle-stimulating hormone concentrations. Ultrasonographic examinations of the reproductive tract documented a reduction in uterine size and vascularity after immunization. The hematocrit level normalized soon after the initial intrauterine hemorrhage, and no recurrence of anemia has been detected. No substantive adverse effects were associated with GnRH vaccination. The results indicate that GnRH vaccination in elephants shows potential for contraception and management of uterine pathology in older elephants.

Zoo elephant research: contributions to conservation of captive and free‐ranging species

“…In the wild, most elephants are either pregnant or lactating and thus experience fewer reproductive cycles in their lifetime, and so they likely experience fewer reproductive‐tract problems, although empirical data are lacking. Use of gonadotropin releasing hormone (GnRH) vaccines to inhibit pituitary FSH and LH release reduces ovarian steroidogenic activity and has been effective in resolving uterine cysts and tumours in older Asian elephants (Boedeker et al ., ).…”

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

“…This female's uterus still appeared to be large (i.e. weighing 32 kg) and not reduced in size, which has been described in one elephant (Boedeker et al ., ) and Indian rhinoceros Rhinoceros unicornis (Hermes et al ., ) when ovarian activity ceases and hormone stimuli on the uterus have been missing. However, the several intramural leiomyoma observed did not exceed 2 cm in diameter and the ovaries were without functional structures.…”

“…Body-weight reduction in obese, elderly elephant cows and the downregulation of ovarian function are the only treatment options. A first case report by Boedeker et al (2012) showed that multiple vaccinations and a sufficient dose of GnRH protein conjugate are required in order to suppress ovarian function and thus cycle activity, as measured by progestagen and titre levels. The female was ultrasonographically monitored, and the leiomyoma stopped growing and even regressed significantly after vaccination (Boedeker et al, 2012).…”

“…Monthly boosters were therefore given in several studies at least at the beginning of the treatment (Rajapaksa et al, 2010;Lueders et al, 2014;Somgird, Homkong et al, 2016). One study in an Asian elephant female showed that a titre rise was only evoked after an adequate GnRH protein-conjugate dose of 12Á5-30 mg (Repro-BLOC ® ) (Boedeker et al, 2012). These initial data suggest that a dose of at least 600-1000 lg of GnRH protein conjugate is required for the initial vaccination along with more regular boosters at the beginning of the vaccination schedule (Valades et al, 2012;Bertschinger & Lueders, 2018).…”

Immunocontraception for Animals: Current Status and Future Perspective

“…Equity ™ and Bopriva ™ (Zoetis) are both GnRH analogue vaccines marketed in Australia for use in horses and beef cattle, respectively. Finally, Repro‐BLOC ® (Amplicon Vaccine, LLC, Pullman, WA, USA) is a recombinant ovalbumin‐GnRH fusion protein vaccine for use in cattle, although there is limited data on its efficacy …”