On 30 August 2002, a 338 pound, male bottlenose dolphin (estimated age 4-7 yrs) stranded alive on Assateague Island National Seashore, near Berlin, MD. Staff and volunteers from the National Aquarium in Baltimore / Marine Animal Rescue Program retrieved and transported the dolphin to their facility in Baltimore. Upon arrival, a physical examination was performed; the animal was listless but appeared to be in good body condition. No other abnormal physical findings were noted. Blood, blow hole samples, and fecal were collected for analysis. Significant abnormal findings included a low PCV (36%), increased sedimentation rate (85), and low serum iron (29ug/dL). Fecal cytology revealed a large number of gram-positive rods, many of which contained central to terminal spores. Acute Clostridium sp enteritis was suspected and treatment with ceftazidime IM (20mg/Kg IM SID) prednisolone sodium succinate (3.3 mg/Kg IM), clindamycin (9.8 mg/kg PO BID) and 1.5L filtered fresh water PO was initiated. Despite treatment, the animal died on 31 August. The Maryland Department of Natural Resources/Fish & Wildlife Health Program was contacted to perform a necropsy examination and arrangements were made to transport the carcass to the Maryland Department of Agriculture/Frederick Animal Health Laboratory, in Frederick, Maryland.
Upon gross necropsy, external observations included numerous rake marks/ lacerations, circular pigmented skin lesions, a small laceration of the left flank and a skin nodule containing thick, flocculent material. Stalked barnacles were attached to the dorsal fin and flukes.
Significant findings internally included discoloration of the myocardium. The left ventricle was mottled tan and brown, with a free wall measurement varying from 1.5 to 4.0 cm thickness. The widest measurement coincided with the pale tan region of the ventricle. On cut section, the pale muscle exuded thick, tan purulent material in unencapsulated cavities in the heart wall. The stomachs contained approximately 100 mL of viscous yellowish fluid. Intestinal contents were markedly viscous and green. Other organs were grossly normal in appearance.
The head was severed and frozen for later examination by the Smithsonian Institution Division of Mammals. Upon thawing and examination, the cerebral cortex and thalamus had coalescing regions of dark red discoloration with marked softening of the tissues. Additionally, Nasitrema sp. parasites were present in pterygoid sinuses.
Bacteriology culture of intestines and heart yielded Clostridium perfringens in both organs. No other bacteria or fungi were reported from other organs.
Histopathologic examination of the heart revealed severe multifocal and regionally extensive acute necrosuppurative myocarditis. Brain tissue had severe acute to subacute multifocal to coalescing necrosuppurative and hemorrhagic encephalitis. Axillary, pulmonary, and other lymph nodes exhibited moderate lymphedema with congestion.
Clostridium perfringens has frequently been cultured from the intestinal tracts of both ill and healthy cetaceans (Walsh et al, 1994), and has caused the death of a captive dolphin (Buck et al., 1987). This is the first report of documentation of Clostridium perfringens infection in a wild bottlenose dolphin in Maryland. This interagency effort was made possible by the cooperation of private, federal and state agencies. Collaboration and information sharing is essential to stranding programs and we wish to thank Jack Kumer, National Park Service for his continued assistance in obtaining access to stranded animals on Maryland beaches.
1. Walsh MT, LA Thomas, JG Songer, TW Campbell, LS Tucker. 1994 Clostridium perfringens isolates from cetaceans. Proceedings of the 25th Annual International Association for Aquatic Animal Medicine Conference, p 95.
2. Buck JD, LL Shepard, S Spotte. 1987. Clostridium perfringens as the cause of death of a captive Atlantic Bottlenose Dolphin (Tursiops truncatus). J. Wildl. Dis 23(3):488-491.