Abstract

This report describes a fatal stingray interaction with a bottlenose dolphin (Tursiops truncatus) and the use of multidetector computed tomography (CT) imaging for determination of cause of death prior to gross necropsy. An adult male bottlenose dolphin was found deceased in May 2017 and brought to the University of Florida for examination. No external signs of trauma were initially appreciated. CT examination revealed a moderate to severe right-sided pneumothorax and three linear mineral-attenuating foreign bodies, one of which was coursing through the mediastinum and pleural space and lodged within the right atrium of the heart. The foreign objects were identified as stingray barbs on gross examination at necropsy. The basilar aspect of the barb within the heart punctured through the right cranioventromedial lung pleura which showed evidence of focal pleuritis. Histopathologic examination showed pneumonia and a fibrinosuppurative endocarditis with associated heartbase hemorrhage. No clear path of travel for this barb was identified. Bottlenose dolphins and many stingray species share a habitat off the Southeastern United States.¹ Interactions are well-documented and injuries sustained can range in severity from incidental to fatal.^{2,3,4,5,6,7,8,9,10} Barb injuries have also been implicated as a possible cause for vague clinical signs in rehabilitating animals.⁹ This case illustrates how CT imaging could be an important antemortem screening tool for clinicians working with stranded or rehabilitating wild dolphins. Furthermore, stingray injury should be considered as a differential in cases of dolphin mortalities or strandings even in the absence of external trauma or in those with unexplained clinical signs.

Acknowledgements

The authors would like to thank Laurie Adler, Mackenzie Russel, Nina Thompson, George H. Burgess, Salvatore Frasca Jr. and Randall Wells for their assistance and expertise with this case. This dolphin originated from Clearwater Marine Aquarium stranding network who have generously supported the post mortem scanning project at UF. Thanks to the CMA veterinary and the rescue team for all of their help and for transporting the animal for scanning.

*Presenting author
+Student presenter

Literature Cited

1.  Scott MD, Wells, RS, Irvine, AB. 1996. Long-term studies of bottlenose dolphins in Florida. J Mar Biol Assoc UK 6:73–81.

2.  Conway JN, Mcfee WE. 2017. Ingestion of stingrays (Dasyatis spp.) by a common bottlenose dolphin (Tursiops truncatus). Aquatic Mammals 43(3): 229–232.

3.  Visser I. 1999. Benthic foraging on stingrays by killer whales (Orcinus orca) in New Zealand waters. Mar Mam Sci 15(1): 220–227.

4.  Spanier E, Goffman O, Kerem D, Lavalli K. 2000. Injury of an Indian Ocean bottlenose dolphin (Tursiops aduncus) in the Red Sea by a stingray spine. Aquatic Mammals 26(3):196–201.

5.  Mcfee W, Root H, Friedman R, Zolman E. 1997. A stingray spine in the scapula of a bottlenose dolphin. J Wildl Dis 33(4): 921–924.

6.  Cfee WE, Lipscomb TP. 2009. Major pathologic findings and probable causes of mortality in bottlenose dolphins stranded in South Carolina from 1993 to 2006. J Wildl Dis 45(3): 575–593.

7.  Duignan PJ, Hunter JE, Visser IN, Jones GW, Nutman A. 2000. Stingray spines: a potential cause of killer whale mortality in New Zealand. Aquatic Mammals 26(2): 143–147.

8.  McLellan WA, Thayer VG, Pabst DA. 1996. Stingray spine mortality in a bottlenose dolphin, Tursiops truncatus, from North Carolina waters. J Elisha Mitchell Sci Soc 112(2): 98–101.

9.  Walsh MT, Beusse D, Bossart GD, Young WG, Odell DK, Patton GW. 1988. Ray encounters as a mortality factor in Atlantic bottlenose dolphins (Tursiops truncatus). Mar Mam Sci 4(2):154–162.

10.  Wells RS, Allen JB, Hofmann S, Bassos-Hull K, Fauquier DA, Barros NB, Delynn RE, Sutton G, Socha V, Scott MD. 2008. Consequences of injuries on survival and reproduction of common bottlenose dolphins (Tursiops truncatus) along the west coast of Florida. Mar Mam Sci 24(4):774–794.