Effect of deslorelin implants on follicular development, parturition and post-partum oestrus in the tammar wallaby...

The effect of treatment with slow release implants containing the GnRH agonist, deslorelin, was investigated in female tammar wallabies. Pouch young were removed from 16 wallabies presumed to be carrying quiescent blastocysts. Eight received a 5 mg deslorelin implant and eight received a placebo implant. Animals were caught daily from day 25 to day 30 and their pouches inspected for newborn young and their urogenital sinus checked for a copulatory plug. Treatment with deslorelin did not affect reactivation of a dormant blastocyst and subsequent birth in 4/8 animals, but post-partum mating was inhibited in these animals. Five control and five treated animals were killed within 0-48 h post partum and their reproductive tracts analysed. At autopsy, all five control animals had large preovulatory follicles but only one deslorelin-treated animal showed signs of follicular development. These differences were also reflected in the weights of the lateral vaginae, with treated animals showing no evidence of oestrogenic stimulation. The remaining three control and three treated animals were monitored for approximately 2 years. The long-term contraceptive effects of a single 5 mg deslorelin implant lasted for just under one year. These results indicate that slow release deslorelin implants inhibit follicular development in the female tammar wallaby for extended periods of time and may have potential application in reproductive management of captive marsupials in the kangaroo family.