Abstract

Alternogest (Regu-Mate®, Hoechst Roussel Vet, DPT Laboratories, San Antonio, TX 78215), a synthetic progestin, has been utilized for birth control in cetaceans at various facilities. It has also been evaluated as a synchronizing tool in killer whales and bottlenose dolphins³. Advances in ultrasonographic monitoring of ovaries (Fiona, Brook 1997)¹, have led to improved monitoring of reproductive paradigms by veterinarians.

At Miami Seaquarium, Regu-Matzhas been utilized therapeutically in a geriatric dolphin with ovarian abnormalities for the past five years. Additionally, a healthy calf was born after an Atlantic bottlenose dolphin had been receiving Regu-Mate® for two years². This clinical data, along with the experiences gained from other facilities, indicated that Regu-Mate® was sufficiently safe to incorporate it in our reproductive management program.

The six cetaceans in our project included two Pacific white-sided dolphins (Lagenorhynchus obliquidens) and four bottlenose dolphins (Tursiops truncatus). After intensively monitoring the reproductive activity of these dolphins for two years we utilized Regu-Mate® at 1 ml per 110 lb. body weight for several reasons. The two Pacific white-sided dolphins showed anestrus for two years. One bottlenose dolphin received it for two years to prevent pregnancy at a physically immature age. One bottlenose dolphin received it to prevent a pregnancy around two extensive surgical procedures. Two other dolphins are founder stock animals, not well represented genetically, and were placed on it to encourage reproduction. The animals were taken off Regu-Mate® when historical data indicated that ovulatory activity had or should occur in that species. Thus the winter months of November through March were excluded. All cetaceans were housed with males.

 Dolphin: #1 Atlantic bottlenose dolphin ovulated on day 20 post cessation of Regu-Mate®. Confirmed by both ultrasonography and elevated serum progesterones. She became pregnant and the period of gestation can be predicted to culminate in April 2002.

 #2 Atlantic/Pacific bottlenose dolphin ovulated on day 20 post cessation of Regu-Mate®. Confirmed by both ultrasonography and elevated serum progesterones. A fluid filled uterus with what appeared to be a fetus was observed but then lost two months later. The serum progesterones were also elevated and dramatically dropped in two months.

 #3 Atlanic bottlenose dolphin ovulated on approximately day 20 post cessation of Regu-Mate®. Confirmation by only elevated serum progesterones. A fluid filled uterus was observed but a fetus could not be confirmed since the dolphin only tolerated the ultrasound for one second at that time. The serum progesterones dramatically decreased two months after ovulation. She did ovulate again and became pregnant two months later. Although the pregnancy is well received, it is not directly attributed to Regu-Mate® and is not being counted in this study.

 #4 Atlantic bottlenose dolphin had active bilateral ovaries with several large follicles and exhibited sexual behavior at the same time frame as those that ovulated. She did not ovulate confirmed by both ultrasonography and lack of elevated serum progesterones. We will be repeating the Regu-Mate® cycle in her in the Spring of 2002.

 #5 Pacific white-sided dolphin ovulated on day 20 confirmed by both ultrasonography and elevated serum progesterones. This dolphin subsequently became pregnant. The period of gestation can be predicted to culminate in June 2002.

 #6 Pacific white-sided dolphin ovulated on day 21 the second time she was cycled off Regu-Mate®. Both ultrasonography and elevated serum progesterones confirmed this. Reproductive behavior followed the same trend as the others and coitus was confirmed with a postcoital sample showing mobile spermatozoa. She however did not become pregnant. Another cycle of Regu-Mate® will be attempted in the summer of 2002.

Five out of the six cetaceans ovulated post Regu-Mate®, but not necessarily after the first cycle on it. Four of the five ovulations occurred at day 20 and one on day 21 post cessation of Regu-Mate®. Ovulation is defined as the last day the follicle was observed as the ovulatory day. Three of the five dolphins that ovulated are still pregnant, but one is not attributed to Regu-Mate® directly. A trend in reproductive behavior was documented during this project since all dolphins were housed with males. The males elicited the females as early as day eight post-Regu-Mate® and the females showed receptivity and even elicitation on approximately day 16 post Regu-Mate®. Reproductive behavior dramatically stopped the day after ovulation. Whenever possible post coital samples were collected to confirm coitus and evaluate the spermatozoa.

Discussion

Regu-Mate® was utilized to encourage ovulation in two pacific white-sided dolphins that had been in anestrus after two years of monitoring. This may be important to encourage ovulation in animals that are non-reproductive yet genetically important. The date of ovulation will give us an exact gestation period for an Atlantic bottlenose dolphin and a pacific white-sided dolphin. Three of the ovulations did not result in pregnancy but two showed evidence of possible miscarriages at an early stage. Regu-Mate® does not consistently cause ovulations, but in this ongoing project the results were very promising and further studies to obtain information on the variables of when it causes ovulation or not need to be further evaluated. In our hands, a cycle of at least 30 days on Regu-Mate® was sufficient to encourage ovulation.

Acknowledgements

We would like to thank all the studies that have moved cetacean reproduction forward from scientists such as Fiona Brooks and Todd Robeck. We would like to thank Rafaella Simoni, graduate student from Italy, for organizing the data. We would like to thank the trainers at Miami Seaquarium.

References

1.  Brook F. 1997. The use of diagnostic ultrasound in assessment of the reproductive status of the bottlenose dolphin, Tursiops aduncus, in captivity and applications in management of a controlled breeding programme. The Hong Kong Polytechnic University, Kowloon, Hong Kong.

2.  Dougherty M, Bossart G, Renner M. 2000, Case study: Calf born thirteen months post-Regu-Mate® contraception with social complications, in Report from the Bottlenose Dolphin Breeding Workshop, Duffield, D.A., and Robeck, T.R. (eds.), American Zoological Association Marine Mammal Taxon Advisory Group, Silver Spring, MD, 41-42.

3.  Robeck TR, E Jensen, F Brooks, N Rourke, C Rayner, R Kinoshita, in Proceedings of the American Association of Zoo Veterinarians and International Association for Aquatic Animal Medicine Joint Conference, 2000, New Orleans, Lousiana, p.222.