Macroscopic and Histopathologic Findings From a Mass Stranding of Rough-Toothed Dolphins (Steno bredanensis) in 2005 on Marathon Key, Florida, USA

Ruth Y Ewing; David S Rotstein; William A McLellan; Alexander M Costidis; Gretchen Lovewell; Adam M Schaefer; Carlos H Romero; Gregory D Bossart

doi:10.3389/fvets.2020.00572

Macroscopic and Histopathologic Findings From a Mass Stranding of Rough-Toothed Dolphins (Steno bredanensis) in 2005 on Marathon Key, Florida, USA

Front Vet Sci. 2020 Sep 2:7:572. doi: 10.3389/fvets.2020.00572. eCollection 2020.

Authors

Ruth Y Ewing¹, David S Rotstein², William A McLellan³, Alexander M Costidis⁴, Gretchen Lovewell⁵, Adam M Schaefer⁶, Carlos H Romero⁷, Gregory D Bossart^{8

9}

Affiliations

¹ Southeast Fisheries Science Center, National Marine Fisheries Service, National Oceanographic and Atmospheric Administration, Miami, FL, United States.
² Marine Mammal Pathology Services, Olney, MD, United States.
³ Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, United States.
⁴ Virginia Aquarium & Marine Science Center, Virginia Beach, VA, United States.
⁵ Directorate of Marine Biology and Conservation, Mote Marine Laboratory, Sarasota, FL, United States.
⁶ Center for Coastal Research-Marine Mammal Research and Conservation Program, Harbor Branch Oceanographic Institute, Florida Atlantic University, Fort Pierce, FL, United States.
⁷ Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States.
⁸ Georgia Aquarium, Atlanta, GA, United States.
⁹ Division of Comparative Pathology, Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL, United States.

Abstract

On March 2, 2005 ~70 rough-toothed dolphins (Steno bredanensis) mass stranded along mud flats and associated canals on the Atlantic Ocean side of Marathon Key, Florida. Forty-six were necropsied and placed into two groups for analysis: Group-1 animals (N = 34; 65%) that died prior to medical intervention and rehabilitative efforts and Group-2 animals (N = 12; 35%) that died in rehabilitation. Thirty-four animals were females (18 adults, 5 juvenile/subadult, 7 calves, and 4 of undetermined age) and 12 were males (6 adults, 4 juvenile/subadults, 1 calf, and 1 of undetermined age). Body condition overall was fair to good in Group-1 and fair to poor in Group-2. Lesions were observed in multiple body systems. Greater than 90% of animals in both groups had respiratory lesions. Verminous sinusitis and bronchopneumonia were 2-3 times more prevalent in Group-2. Capture/exertional rhabdomyolysis was observed in Group-2 (42%). Vacuolar hepatopathies were observed in both groups including hepatic lipidosis (Group-1) and mixed etiologies (Group-2). Pancreatic and gastrointestinal tract pathologies were prevalent in Group-2 animals 56 and 75%, respectively, and included gastritis, gastric ulceration, enterocolitis, pancreatic atrophy, and pancreatitis related to physiologic stress. Group-2 more frequently had evidence of hemorrhagic diathesis present which included increased extramedullary hematopoiesis in various organs, increased hemosiderosis, and hemorrhage and hemorrhagic drainage in various organs. Central nervous system disease, primarily edema, and mild inflammation were equally prevalent. Renal proteinuria, tubular necrosis, and pigmentary deposition were observed in Group-2. Dental attrition was observed in ~40% of the groups. Gammaherpesviral-associated pharyngeal plaques were observed in 46 and 54% of Group-1 and 2 animals, respectively. Other lesions observed were mild and incidental with a frequency rate <20%. The findings from this Steno stranding provide a unique window into baseline individual and population clinical conditions and additional perspective into potential clinical sequelae of rehabilitation efforts.

Keywords: Florida; Steno bredanensis; USA; mass stranding; pathology; rough-toothed dolphin.