Abstract
The health of common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, LA (BB) was heavily impacted by exposure to oil following the Deepwater Horizon oil spill in 2010,1-4 though the cardiac effects of oil on dolphins had not yet been evaluated. In 2018, techniques for cardiac evaluation were developed with dolphins at the U.S. Navy Marine Mammal Program (MMP). The techniques were then applied to wild dolphins examined during capture-release health assessments in BB, as well as in Sarasota Bay, Florida (SB), a reference population. Cardiac auscultation detected systolic murmurs in the majority of animals (88.2% in BB, 89.5% in SB). Echocardiography showed most to be innocent flow murmurs attributed to elevated blood flow velocity. Telemetric 6-lead electrocardiography detected arrhythmias in BB dolphins (43%) and SB dolphins (31%), all of which were considered low to moderate risk for adverse cardiac events. Echocardiography showed several differences between BB and SB dolphins, including significantly thinner left ventricular walls in BB dolphins (IVSd/Ao, p=0.003 and LVPWd/Ao, p=0.033). BB dolphins also had smaller left atrial size (p=0.004), higher prevalence of tricuspid valve prolapse (p=0.004), and higher prevalence of tricuspid valve thickening (p=0.045). Further work is needed to elucidate whether these differences between the two populations are due to physiologic differences or indicative of cardiac disease. Two dolphins in BB were diagnosed, for the first time for cetaceans, with pulmonary arterial hypertension (PH) based on Doppler echocardiography-derived evidence of elevated pulmonary arterial pressures and dilated main pulmonary arteries.
Acknowledgements
The authors wish to thank the wonderful MMP veterinary technicians and trainers for their support, especially Veronica Cendejas, Jammy Eichman, Henry Cao, and Anthony Perron, as well as Jay Sweeney for his help with transesophageal echocardiography. This research was made possible by a grant from The Gulf of Mexico Research Initiative. Barataria Bay health assessments were conducted under NMFS Scientific Research Permit No. 18786, issued to NOAA Fisheries Marine Mammal Health and Stranding Response Program, and approved by the NOAA Animal Care and Use Committee. Sarasota Bay health assessments were performed under National Marine Fisheries Service Scientific Research Permit No. 20455 and approved by Mote Marine Laboratory’s Institutional Animal Care and Use Committee.
*Presenting author
Literature Cited
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