![]() Some have medical histories stretching to over 50 years, which serve to show how heart health evolves over a dolphin’s lifetime. These dolphins have regular health assessments and are trained to react to the signals of trainers. The United States Navy has a population of dolphins that live in the San Diego Bay, cared for by a mixed team of military, government, and contractor personnel, including NMMF veterinary and training staff. So, how do you go about defining a whole medical discipline for a wild animal that spends its entire lifetime underwater? In this case, the CARMMHA team got lucky. “Early studies even referred to the dolphin heart as practically inaudible.” Barbara Linnehan, National Marine Mammal Foundation Deputy Director of Medicine and former Postdoctoral Veterinary Fellow on the CARMMHA cardiac project. “Previously, there was no published information regarding the technique of ausculting dolphin hearts or regarding prevalence of murmurs in dolphins,” said Dr. Even listening to the heart using a stethoscope, an assessment technique called auscultation, had never before been described. In 2018, they would return to Barataria Bay, but before a thorough assessment could be completed there would need to be a major overhaul of procedure. In order to properly assess dolphin heart health, Smith and a team of CARMMHA scientists and veterinarians, including two veterinary cardiologists, needed to enhance dolphin cardiology for field ready deployment. While we know much about the heart health of humans, dolphins are trickier to assess, owing to their marine lifestyle. ![]() Part of the problem was the lack of understanding about dolphin heart health. “We started to wonder, have we been missing something or is this a new problem that is emerging?” “We were noticing that we were hearing a lot of heart murmurs, and that was intriguing because of all the results coming from the bird and fish research about oil cardiotoxicity,” said Smith, National Marine Mammal Foundation Chief Medical Officer and Co-Principal Investigator of the Consortium for Advanced Research on Marine Mammal Health Assessment (CARMMHA), a part of the Gulf of Mexico Research Initiative. But instead of the classic “lub dub” sound, some of these dolphins had a heartbeat with an extra sound, a “lub dub shhh.” It turns out, many of the dolphins in Barataria Bay that Smith was studying had heart murmurs. A healthy dolphin heart makes a syncopated beat, just like a human. During a physical examination, Smith and her team discovered something concerning. In 2016, Smith was monitoring the health of a specific population of bottlenose dolphins in Barataria Bay, Louisiana as part of the Natural Resource Damage Assessment following the Deepwater Horizon oil spill. Cynthia Smith, listening to hearts is part of the job.
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