By Marie Kubiak
Meerkats are a charismatic and popular exhibit in zoo collections and they are typically maintained in their natural family groups. One dominant pair in each group is responsible for breeding and can produce up to four litters of one to six pups a year. As such, successful breeding can quickly result in overpopulation of an animal with IUCN conservation status of ‘Least concern’, with limited opportunities to relocate animals within the zoo community. Additionally, if social structure of a group breaks down and the dominant pair are displaced then inbreeding between younger members of the group can result. In either scenario, contraception is useful in managing unwanted breeding. Deslorelin acetate implants are advocated for contraception in many mammalian species, including meerkats (Suricata suricatta) but recommendations are based entirely on anecdotal reports with no objective data to demonstrate efficacy or safety.
This study followed two groups of meerkats: one group with contraception, using deslorelin 4.7 mg implants every 12 months to prevent inbreeding following social structure breakdown; and one group without contraception, to assess the efficacy of this treatment on breeding cessation. The group that used contraception produced no further litters for the entire 600-day observation period, while the control group continued to breed. Following control group expansion, the control group was also given deslorelin implants after 12 months for population management reasons, resulting in suppression of further conception, although one female successfully carried her litter to term. This litter was exceptionally large at seven pups and conception may have occurred in the hyperstimulatory stage in the two weeks following implantation.
No adverse effects on health or behaviour were associated during daily observation and annual clinical examination of all animals. Effective contraception appeared to result from implant placement in both sexes. As the meerkats were kept under the same dietary and management conditions, it would be expected that if environmental factors alone were responsible for the cessation in breeding in the group that received contraception, then a similar failure to reproduce would be seen in the group that did not receive contraception during the same time period. No disruption to the social hierarchy was noted following contraception and, interestingly, it appeared that the dominant pair in each group maintained their social status even when one received contraception and breeding was not occurring.
It was noted in this study that implanted males had a notable reduction in testicular size and this may be a useful criterion for assessing implant efficacy and monitoring duration of action. A duration of action of at least 12 months is expected based on the findings from this study.
More details about this case can be found here: http://vetrecordcasereports.bmj.com/content/4/1/e000281.full