Abstract

The Florida manatee is a federally listed endangered species that lives in fresh and coastal marine waters throughout the southeastern United States. Despite extensive research on basic anatomy and physiology, limited research has been performed pertaining to the cardiovascular system of this species or associated underlying cardiac conditions.^1-4 Given recent federal mandates to release all captive animals deemed healthy by the attending clinician, it is imperative that all organ systems be critically evaluated prior to release to provide the best chance for survival of the animal following release. Identification of any underlying cardiac condition the manatee may be susceptible to and the prevalence within the population, may allow for improved long-term management of the species both in the wild and in captivity. Echocardiography, which has not been previously described in this species, is part of a complete cardiac work-up, and is considered the gold standard in diagnosing functional and structural abnormalities. Due to the manatee's unique anatomy, traditional lateral ultrasonographic imaging modalities are not applicable. Thus, we have developed a technique for performing echocardiography via a ventral approach. Through construction of a table made from pressure-treated wood and polymer board with a large cardiac window, cardiologists were able to perform echocardiography. The study population consisted of 21 male and female wild-caught and captive animals of various sizes. Echocardiography was performed in the field using a portable battery and ultrasound. Because of their unique thoracic anatomy, not all images considered standard in domestic echocardiography were attainable. This limited objective measurements to those involving the length and width of the left atrium, left ventricular ejection fraction, and the peak velocity of left ventricular outflow. In addition to objective measurements, color-flow Doppler allowed visualization of valvular regurgitation across both the mitral and tricuspid valves in a few individuals. With the establishment of a technique for echocardiography in the manatee, the next phase of this study is to establish normal cardiac parameters based on the aforementioned measurements in various demographic populations of clinically healthy Florida manatees. Echocardiography, in conjunction with other diagnostic tests, can then be used by veterinarians to determine the overall cardiac health of an individual animal. It can also be used as a reference for cardiac surveillance studies on the wild population.

Acknowledgements

We would like to thank Mrs. Melanie Powell of the University of Florida - College of Veterinary Medicine, Mrs. Anna Panike, Mr. Brandon Bassett, Mr. Andy Garrett, Mrs. Amber Howell, Mrs. Donna Szemer, and Mr. Kane Rigney of the Marine Mammal Pathobiology Lab (FWC), Mr. Bob Bonde and the U.S. Geological Survey, and all of the clinical and keeper staff at Tampa's Lowry Park Zoo. The authors would also like to thank the University of Florida - College of Veterinary Medicine for financial support of this study.

References

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