Contraceptive effect of a gonadotropin-releasing hormone vaccine on a captive female African Lion (Panthera leo): a case study

The Use of Gonadotropin Releasing Hormone to Manage Intraspecific Agonism in a Coalition of Male Lions (Panthera leo)

While housing nonbreeding all-male social groups of African lion (panthera leo) is a necessary part of managing this polygynous species ex situ, resulting intraspecific agonistic behavior can negatively impact animal welfare and guest experience, undermining two primary objectives of modern zoological gardens. Improvest is a gonadotropin releasing factor analog-diphtheria toxoid conjugate marketed for temporary immunological castration which has proven successful in reducing aggression in other zoo-housed species. To the authors' knowledge, the use of this technique has not been described in male African lions; reticence to use GnRH agonists may stem from concern about phenotypic effects (mane loss) and zoo visitor perception. We describe the use of Improvest in conjunction with other management changes to manage agonism in a coalition of African lions (3.0) housed at the Oakland Zoo. Daily agonism scores were calculated via animal care staff records, fecal testosterone levels were measured, and monthly photos were taken to monitor phenotypic changes. While agonism scores varied seasonally in three pretreatment years, a significant (p < 0.05) reduction in the frequency of agonistic behavior began within 2 months of initial treatment. Two lions showed testosterone suppression within 2 months of receiving the first vaccine, while the third showed suppression beginning in the period 4 months after the first vaccine. Mane loss occurred in all three lions, and time to mane regrowth varied between individuals. Improvest, combined with other management strategies, decreased overall fecal testosterone and intraspecific agonism in these lions, and may be an effective tool in other male coalitions.

Contraceptive effect of a gonadotropin-releasing hormone vaccine on captive male brown bears (Ursus arctos)

Fertility control has traditionally been applied in zoos to control captive populations, and reversible contraception is important. However, contraceptive methods for male bears have not been reported. We aimed to establish a reversible contraceptive for male brown bears by investigating the effects of a gonadotropin-releasing hormone (GnRH) vaccine (Improvac®) that was developed for the immune castration of pigs. We vaccinated six bears with two sequential doses of 400 (n = 2) or 600 μg Improvac® (n = 4) with a 1-month interval during the pre-breeding season (February to April). We compared the reproductive parameters (testosterone levels and semen parameters) of the six vaccinated and four non-vaccinated (control) bears once during the breeding season (May or June). To investigate whether the reproductive performance could be restored in the following year of contraception, we also compared the reproductive parameters once during the breeding season in two bears between the year with GnRH vaccination and the following year without vaccination. Vaccination treatments suppressed reproductive parameters in 5 bears, although vaccination with 400 μg of Improvac® was not effective in one bear. Testosterone levels and the rate of progressive sperm motility were significantly lower, and total sperm count and testis size tended to be lower in vaccinated bears, compared with the controls. Blood biochemical findings and direct observations after Improvac® vaccination did not reveal side effects. Moreover, testosterone levels and spermatogenic scores of two bears were restored in the following year. We confirmed that the Improvac® vaccine elicited a reversible contraceptive effect in male brown bears.

A new approach to the vasectomy of African lions (Panthera leo)

Four healthy, male, adult African lions (Panthera leo) were presented for vasectomy, which was performed for management purposes. After immobilisation with medetomidine and tiletamine/zolazepam the lions were intubated and anaesthesia was maintained with isoflurane. In each animal, the ductus deferens was located bilaterally, dissected and transected. Following ligation, a technique commonly used in human medicine called fascial interposition, was used to decrease the chances of recanalisation. Using this technique, the prostatic end of the ductus was fixated outside the tunica vaginalis, while the testicular end remained within the tunic. Histopathology was performed in all cases to confirm the presence of the ductus deferens tissue. During the follow up, twelve months later, no complications were noticed by the owner and no new litters have been born since.

Wound Retractor Laparoscopic Port System for Laparoscopic Ovariectomy in Panthera leo

The aim of this study was to assess the feasibility and intraoperative complications of performing ovariectomies in African lionesses (Panthera leo) using a wound retractor laparoscopic platform. Six lionesses (n = 6) were included. The surgical procedures were carried out through three portals, with a retractor platform positioned at the umbilical port and cannulas placed 3–4 cm from the cranial and caudal regions to the device at the level of the midline. An ovariectomy was performed with a vessel-sealing device. We evaluated the surgery time and the intraoperative and early postoperative complications. The mean weight was 172.83 kg. The total surgery time was 49.33 min. The installation step took a mean of 10.33 min to complete. The mean ovariectomy time was 20 min. Controlled bleeding was observed at the tip of the uterine horn in two cases due to excessive tissue thickness. The retrieval of dissected ovarian tissue and annexes was easily performed. No other complications were observed. The use of the laparoscopic platform during three-portal surgeries for laparoscopic ovariectomy in adult overweight lionesses is feasible and without intraoperative problems. The retractor meant that there were no entry-related issues due to the 25 mm mini-laparotomy. It also made it simpler to extract thick ovaries and promptly re-establish the pneumoperitoneum.