163 RE-ESTABLISHING REPRODUCTIVE CYCLICITY IN A FEMALE ASIAN SMALL-CLAWED OTTER FOLLOWING SUPRELORIN-INDUCED CONTRACEPTION: A CASE STUDY

Abstract

Asian small-clawed otters (ASCO) are a popular species to exhibit in zoological institutions globally, and are found in managed populations in the United States, Europe, Asia, and Australia. Captive breeding of these otters is integral to population sustainability, with management programs using pedigree analyses to make specific breeding recommendations to ensure long-term genetic viability. Because of the familial social structure of ASCO and limited space within zoos, physical separation of animals is not always possible for temporary breeding prevention, and short-term contraception may be preferred. In US zoos, Suprelorin (deslorelin; Virbac Australia, Milperra, Australia), a GnRH agonist, has been recommended for contraception of female carnivores, due to its small implant size and lack of side effects often associated with hormone-based contraceptives. However, the duration of reproductive suppression with Suprelorin may be excessive and reversibility (i.e. resumption of cyclicity, ovulation, and pregnancies) in implanted females across a range of species has been variable, unpredictable, and prolonged. Since 2006, 49 female ASCO have been implanted with Suprelorin at least once, and, of these, only two females have shown confirmed reversibility with pregnancies. No ASCO females implanted more than once have thus far exhibited reversibility (personal communication, AZA Wildlife Contraceptive Center, St. Louis, MO, USA). In this case study, fecal hormone monitoring of one female ASCO implanted with Suprelorin three times (Dec 2007, Jan 2009, Mar 2010), showed a lack of ovarian cyclicity and ovulation during the three years since her last implant. In an attempt to induce ovarian follicular growth and ovulation, this female was injected (IM) with exogenous gonadotropins (100 IU of equine chorionic gonadotropin followed 80 h later with 3000 IU of porcine luteinizing hormone). Fecal progesterone monitoring confirmed ovulation followed by a 76 day pseudopregnancy, with temporal characteristics similar to those previously reported in naturally cycling ASCO (Bateman et al. 2009 Zoo Biol. 28, 107–126). Following the induced pseudopregnancy and ~55 days of basal progestin levels, this female was observed breeding with a cohabitating ASCO male. Fecal hormone monitoring revealed subsequent ovulation and the occurrence of another pseudopregnancy of normal duration. These preliminary findings suggest that exogenous gonadotropin treatment may be useful for promoting resumption of normal ovarian cyclicity and ovulatory responses in ASCO following prolonged reproductive suppression with Suprelorin.