Progesterone Concentration and Ultrasonography During Pregnancy in the Amazon River Dolphin (Boto), Inia geoffrensis
Abstract
This study was conducted in November 2006, 2007 and 2008 during an annual capture campaign as part of a long-term research project of wild Amazon River dolphins, Inia geoffrensis, in the Mamirauá Reserve in the central Amazon. While the animals were out of the water they were measured, weighed, marked and their age was estimated. Blood samples were taken from the ventral fluke veins and ultrasonography (Sonosite 180 Plus with a C60/5-2 MHz probe) was applied. Forty seven female botos underwent examination of the reproductive organs by real-time B-mode ultrasonography using the method of Brook.1 Fetal measurements were performed as described by Lacave.2 The presence of a fetus in the gestational sack, fetal movement and fetal heartbeat were considered as criteria for pregnancy. Twenty females were considered to be pregnant in the first and second trimester. In ten animals the thoracic diameter (range: 1.5-12.0 cm), in five females the biparietal diameter (range: 2-5 cm) and in seven animals the total length (range: 5-20 cm) of the fetus could be measured. In sixty six females plasma progesterone (P4) levels where evaluated by RIA. The P4 levels in non pregnant adult botos ranged from 0.04 to 8.82 ng/ml (non-lactating) and from 0.12 to 8.75 ng/ml in lactating animals. In pregnant botos P4 levels ranged from 9.31 ng/ml to 23.74 ng/ml (lactating) and from 14.84 ng/ml and 29.98 ng/ml in non-lactating pregnant animals. P4 values above a threshold level of 10 ng/ml may be a useful indicator of pregnancy in wild.
Acknowledgements
This work was supported by a grant from the LMU International Office and the DAAD, Germany. The author wishes to thank the INPA Institution for providing the ultrasound equipment, the Projeto Boto for field support, the Instituto de Desenvolvimento Sustentável Mamirauá (IDSM) for access to the animals and the Laboratório de Dosagens Hormonais, University of São Paulo for the blood analyses.
References
1. Brook FM. 2001. Ultrasonographic imaging of the reproductive organs of the female bottlenose dolphin, Tursiops truncatus aduncus. Reproduction 121(3):419-428.
2. Lacave G, Eggermont M, et al. 2004. Prediction from ultrasonographic measurements of the expected delivery date in two species of bottlenose dolphin (Tursiops truncatus and Tursiops aduncus) Veterinary Record 154:228-233.