Abstract

Following the Deepwater Horizon (DWH) oil spill in 2010, poor pulmonary health and reproductive failure in coastal bottlenose dolphins (Tursiops truncatus) in the northern Gulf of Mexico were well documented.^1,2,3,4,5 The increased fetal distress and pneumonia observed in affected perinatal dolphins could be caused by hypoxia in the dam from concurrent lung disease.⁶ The objective of this study was to evaluate the utility of blood gas analysis and capnography in determining oxygenation status in bottlenose dolphins with and without pulmonary disease. In 2016, samples were collected from 36 wild-caught dolphins in Barataria Bay, Louisiana (BB), during a capture-release health assessment program and from 30 managed dolphins from the Navy Marine Mammal Program in San Diego, CA (NMMP), as a control population with known health histories. Capnograph and select blood gas parameters were compared across population, sex, age or length class, reproductive status, and pulmonary disease status (both clinical and sonographic). Animals with sonographically-detected lung lesions had higher bicarbonate concentrations in their blood than healthy animals (p=0.0001). BB males had higher PCO₂ (p=0.0206) and ETCO₂ (p=0.0496) than females. BB dolphins also had higher hematocrit than NMMP dolphins (p<0.0001). Furthermore, a positive correlation was found between ETCO₂ and PCO₂ (p=0.0088), with a mean difference of 9.5 (p<0.0001), indicating that portable capnography is a clinically useful, field-tested, non-invasive method to approximate the partial pressure of carbon dioxide in dolphin blood. The findings of this study are supportive of both capnography and blood gas as tools to evaluate respiratory status in dolphins.

Acknowledgements

The authors would like to thank our project partners at the National Oceanic and Atmospheric Association (NOAA), U.S. Navy Marine Mammal Program, Auburn University, Louisiana Department of Wildlife and Fisheries, University of Illinois College of Veterinary Medicine, Chicago Zoological Society, and the University of Connecticut. Thanks also go to Deb Fauquier of NOAA Marine Mammal Health and Stranding Response Program, Dr. Tres Clark of Audubon Nature Institute, and Dr. Lydia Staggs of Gulf World for providing veterinary support during this project. We would like to thank Katie Moore of the International Fund for Animal Welfare for assistance with capnograph data collection in Louisiana and Kevin Carlin of the National Marine Mammal Foundation for initial comments on data analysis. Additionally, this work would not have been possible without the incredible field team in Barataria Bay and NMMP husbandry staff and veterinary technicians. The dolphin health assessments in Barataria Bay were conducted under NOAA National Marine Fisheries Service permit no. 18786. Protocols were reviewed and approved by NOAA Institutional Animal Care and Use Committee. This research was made possible by a grant from The Gulf of Mexico Research Initiative.

* Presenting author

Literature Cited

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