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.

Efficacy and Safety of Native and Recombinant Zona Pellucida Immunocontraceptive Vaccines Formulated with Non-Freund's Adjuvants in Donkeys

This study aimed to test zona pellucida (ZP) vaccines’ immunocontraceptive efficacy and safety when formulated with non-Freund’s adjuvant (6% Pet Gel A and 500 Μg Poly(I:C)). Twenty-four jennies were randomly assigned to three treatment groups: reZP (n = 7) received three doses of recombinant ZP vaccine; pZP (n = 9) received two doses of native porcine ZP; and Control group (n = 8) received two injections of placebo. Jennies were monitored weekly via transrectal ultrasonography and blood sampling for serum progesterone profiles and anti-pZP antibody titres. In addition, adverse effects were inspected after vaccination. Thirty-five days after the last treatment, jacks were introduced to each group and rotated every 28 days. Vaccination with both pZP and reZP was associated with ovarian shutdown in 44% (4/9) and 71% (4/7) of jennies, 118 ± 33 and 91 ± 20 days after vaccination, respectively (p > 0.05). Vaccination delayed the chances of a jenny becoming pregnant (p = 0.0005; Control, 78 ± 31 days; pZP, 218 ± 69 days; reZP, 244 ± 104 days). Anti-pZP antibody titres were elevated in all vaccinated jennies compared to Control jennies (p < 0.05). In addition, only mild local injection site reactions were observed in the jennies after treatment. In conclusion, ZP vaccines formulated with non-Freund’s adjuvant effectively controlled reproduction in jennies with only minor localised side effects.

Effects of a Recombinant Gonadotropin-Releasing Hormone Vaccine on Reproductive Function in Adult Male ICR Mice

Gonadotropin-releasing hormone (GnRH) regulates the reproductive endocrine system in mammals. The GnRH immunocontraception vaccine can aid animal population control and management. We evaluated a recombinant GnRH fusion protein with the adjuvant MONTANIDE ISA 206 VG as a GnRH vaccine in adult male ICR mice by evaluating anti-GnRH antibodies; concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone; testis size and histomorphology; and semen quality. Response was assessed after intramuscular administration of the vaccine to mice in weeks 0, 4, and 8. The vaccine induced specific antibody response by week 5, with peak of antibody levels observed by week 13 and a declining level thereafter until the end of the study at week 24. Furthermore, it reduced serum FSH, LH, and testosterone concentrations. The vaccinated mice exhibited testicular atrophy and reduced sperm quality, concentration, morphology, and viability compared to control males. The outcomes of pairings of treated males with untreated females revealed reduced mating, pregnancy rates and number of litters compared to control pairings. Assessment of this GnRH vaccine in different species could assist its development for future applications.

Researching immunocontraceptive vaccines with mares (Equus caballus) as both a target and model for African elephant (Loxodonta africana) cows: A review

A sequence of studies is reviewed that reported the domestic horse (Equus caballus) mare as an appropriate and accessible research platform for recording clinical and laboratory data post-immunisation with anti- GnRH and -zona pellucida (ZP) immunocontraceptive vaccines. Experience with a native porcine ZP (pZP) vaccine in African elephant (Loxodonta africana) cows highlighted needs for improving vaccine formulations and more clearly defining associated ovarian effects and safety profiles. Initially, the efficacy, reversibility and safety of the GnRH vaccine Improvac^® in mares was demonstrated using reproductive tract ultrasonography and concurrently measuring serum antibody titres and progesterone concentrations. Results informed the study design and minimally invasive monitoring of post-treatment ovarian steroid responses of this vaccine in free-ranging African elephant cows. A subsequent sequence of studies reported reversible contraceptive and immunological efficacy in pony mares immunised with pZP formulated with Freund's adjuvants. By comparison, mares treated with a recombinant ZP3 and ZP4 (reZP) vaccine showed disappointing responses. Unexpectedly, most pZP-treated mares showed ovarian inactivity. In attempting to understand this response, results showed the involvement of cytotoxic (CD8+) T-cells negatively correlated to serum ovarian steroid and anti-Müllerian hormone (AMH) levels. Of concern was the prevalence of injection-site lesions ascribable to Freund's adjuvants. Following this, mares treated with both pZP and a novel reZP vaccine formulated with non-Freund's adjuvants showed comparable immunological responses and ovarian inactivity, notably without adverse treatment reactions. In addition, measuring AMH showed promise for monitoring ovarian function in anti-ZP-treated animals.

Contraception of prepubertal young can increase cost effectiveness of management of overabundant koala populations

Context With limited resources for wildlife management and conservation, it is vital that the effectiveness of management programs is maximised and costs reduced. Koala populations need to be reduced in locations where they are locally overabundant and over-browsing their food trees. Subcutaneous contraceptive implants containing levonorgestrel are currently used to control koala fertility to assist in reducing population densities. Dependent young are caught with their mothers, so are also available for contraception. Aims The overall aim was to investigate whether the effectiveness of koala contraception programs can be improved by administering levonorgestrel implants to female young along with their mothers. This was achieved by: (1) determining if implanting females before sexual maturation affects their fertility, growth and pouch development; and (2) developing a stage-structured population growth model to compare two management scenarios. Methods Juvenile female koalas (11–17 months old) were treated with either a control (n = 5) or 70 mg levonorgestrel implant (n = 5). Koalas were caught every 4 to 6 weeks for 15 months, then every 3 to 12 months for 5 years. Koalas were weighed and head length measured. Pouches were checked for young. Pouch development was assessed as a proxy for sexual maturation. A stage-based population model simulating koala population growth was developed to compare different management scenarios: no treatment; treatment of adults only; and treatment of adults plus their dependent young. Key results Levonorgestrel implants prevented births with no effect on growth, survival or timing of sexual maturation. Population growth simulations indicate that treating dependent young with their mothers results in earlier population reduction. Conclusions The treatment of prepubertal female koalas with levonorgestrel implants is a safe and effective method that increases the effectiveness of koala contraception programs. Implications Development of novel strategies may provide opportunities to increase the efficiency and cost-effectiveness of management programs with constrained resources.

The use of contraceptive techniques in managed wild African lion (Panthera leo) populations to mimic open system cub recruitment

Context Managed wild lions (Panthera leo) are lions found in smaller (&lt;1000 km2), fenced protected areas that hold a substantial portion of South Africa’s wild lion population. Because the natural population control mechanisms are compromised within these properties, managers must actively control population growth rates. Fecundity control is used by wildlife managers, but long-term, empirical data on the impact and consequences of such interventions in lions are lacking. Aims The aim of the present study was to assess the effectiveness of two methods of contraception (deslorelin implant and unilateral hysterectomy) in reducing cub recruitment of managed wild lions. Methods Survey data spanning 14 years from 94 managed wild lions on 19 protected areas were used to evaluate the effectiveness of deslorelin implant treatments and unilateral hysterectomies on population growth rates through mimicking open system cub recruitment. Key results Deslorelin implants were effective at increasing the age of first reproduction and lengthening inter-birth intervals. There was also an unexpected decrease in litter size. Behavioural side-effects were recorded in 40% of individuals: 19% pride fragmentation; 13% lack of receptiveness towards males; 8% other. The more successive deslorelin implants a lioness had, the more likely it was that weight gain was reported. Unilateral hysterectomy resulted in a decrease in litter size post-surgery, but this was not statistically significant. No behavioural or physiological side-effects were noted after unilateral hysterectomy. Conclusions Deslorelin treatment was more effective in reducing the reproductive output of managed wild lionesses than unilateral hysterectomy surgery. While more side-effects were associated with deslorelin implants than unilateral hysterectomies, a single deslorelin treatment is currently a good option for fecundity reduction. More research is required on unilateral hysterectomy surgery. Implications Neither deslorelin implants nor unilateral hysterectomies offer a ‘silver bullet’ solution for reducing rapid population growth in managed wild lions. Reproductive control should be integrated with other best-practice approaches.

Porcine zona pellucida vaccine immunocontraception of African elephant (Loxodonta africana) cows: A review of 22 years of research

Background: The native porcine zona pellucida (pZP) vaccine has been successfully used for immunocontraception of wild horses, white-tailed deer and approximately 90 zoo species for more than 25 years.Objectives: To provide proof of concept and test contraceptive efficacy of pZP in African elephants. Once completed, test the population and behavioural effects on cows in the Greater Makalali Private Game Reserve (GMPGR). Following the GMPGR, test efficacy, population effects, safety and reversibility in 25 reserves with populations ranging from 9 to 700 elephants.Method: Histological sections were reacted with anti-pZP antibodies to provide proof of concept. From 1996 to 2000, 21 and 10 cows were treated with pZP vaccine in the Kruger National Park (KNP) and monitored for pregnancy. Population effects of pZP with Freund’s adjuvants (three vaccinations in Year 1 with one annual booster) were studied on 18 cows in the GMPGR. Another six game reserves with a total of 90 cows were added to the project. The project was then expanded to include another 18 reserves.Results: Binding of anti-pZP antibodies to elephant zona proteins was demonstrated in vitro. The KNP provided efficacy results of 56% and 80%, respectively. The contraceptive efficacy in the GMPGR and additional six reserves was 100% following calving of pregnant cows. Safety and lack of impact on social behaviour were demonstrated. In larger populations, efficacy was 95%.Conclusion: Contraceptive efficacy and safety of pZP vaccine could be demonstrated in small to large populations. The methodology is now being implemented in approximately 800 cows on 26 reserves across South Arica.