Introduction

An Atlantic bottlenose dolphin (Tursiops truncatus) was observed for 7 hours in Florida bay swimming slowly at the surface and unable to submerge. The animal was captured and taken to a marine mammal treatment facility near Miami, Florida. Initial examination revealed severe, generalized edema and soft tissue swelling. A hypersensitivity response to an unidentified antigen was initially suspected. A later assessment indicated that musculoskeletal damage, possibly secondary to trauma, may have contributed to the animal's debilitation. The soft tissue reaction may have been secondary to sunburn and windburn acquired while the animal was disabled at the surface. After 2 months of therapy the dolphin was clinically normal and was released near the area from which it had been captured.

Case Report

A disabled Atlantic bottlenose dolphin (Tursiops truncatus) was recovered from Florida Bay where it had been observed swimming slowly at the surface for 7 hours, apparently unable to submerge or dive normally. After Capture, the dolphin was determined to be an adult male, 229 cm in length, and weighed 137 kg. The animal was dyspneic due to constriction of the respiratory passage associated with soft tissue swelling of the pharynx. Inability to close the mouth and extrusion of the penis demonstrated severe and generalized edema. A 12 cm abrasion was noted on the right flank, and third degree sunburn was extensive on the dorsal surface.

Supportive therapy was initiated. Sunburned areas were treated topically with nitrofurazone ointment and zinc oxide. Gentamicin (5mg/kg) and dexamethasone (10 mg) were administered by intramuscular injection prior to transit to a treatment facility.

The dolphin was placed in 1 m of sea water in an isolation tank at a marine mammal treatment facility near Miami, Florida. Respiration stabilized and reduction of soft tissue swelling occurred during the first 48 hours. Parenteral therapy with gentamicin, dexamethasone, and diphenhydramine (0.2 mg/kg) was continued twice daily.

Force-feeding via stomach tube was initiated on day 2 to correct dehydration and consisted of a high potency vitamin supplement (Staminatom, Ziron Laboratories, Miami, Fl), cod liver oil, and electrolytes (Lactated Ringers, American McGraw, Irvine, Ca). Hematologic exam indicated a slight anemia (PCV of 37%) and an eosinopenia.

Daily therapy continued and 4 to 5 kg of whole fish, Atlantic herring (Clupea harengus), and mackerel (scomber scombrus), was added to the force-feeding regime. Water and vitamins were injected into food fish prior to feeding. The dolphin was to be released after recovery and therefore was not conditioned to the usual hand-feeding methods associated with captivity. Parenteral prophylactic administration of thiamine hydrochloride 4 mg/kg) was given on day 5 (1970, J. Am. Vet. Med. Assn. 157(5):559-562).

Following a week of therapy the generalized edema had decreased markedly and the dolphin was swimming more vigorously. Locomotion remained abnormal. The animal made no attempt to submerge but remained with its dorsal surface exposed. A foul smelling, white, cheesy, necrotic exudate was observed lining the buccal surface and oral cavity. Cephalexin monohydrate (2 g/day) was added to the daily fish ration. Over the next 48 hours the tongue became erythematous and there was no improvement of the oral exudate.

By the second week, leukocytosis and neutrophilia were noted. Lactate dehydrogenase, alkaline phosphatase and aspartate transaminase activity were markedly increased. Broad spectrum antibiotics and anti-inflammatory agents were continued through the fourth week. Topical therapy with lanolin, nitrofurazone, and zinc oxide was discontinued after abraded and sunburned areas had healed. A leukocytosis persisted through the fourth week. Serum liver enzymes gradually returned to normal.

The locomotory disorder continued in that only the distal portion of the peduncle and fluke were used for swimming and the animal remained unable to submerge. An abnormal, concave curvature was evident anterior to the dorsal fin. There was concern that the thoracic vertebrae had been damaged and treatment with phenylbutazone (4 mg/kg) was initiated for its anti-inflammatory and analgesic action. Following an additional month of rest and supportive therapy, the dolphin was able to swim and dive normally. It was released in Florida Bay 8 weeks after initial capture.

Discussion

This case represents a unique clinical presentation and is one of the few instances in which a rehabilitated cetacean has been returned to the wild. A definitive diagnosis was not achieved in this case. A severe hypersensitive response to a foreign antigen may have precipitated the massive edema and soft tissue swelling. The clinical response to anti-inflammatory agents supports this assessment. A traumatic incident resulting in vertebral damage cannot be ruled out. Tissue swelling and dehydration may have been secondary to the animal being stranded at the surface. As the dolphin responded well to rehydration, broad spectrum antibiotics and supportive care a definitive diagnosis was not pursued. Stress associated with diagnostic procedures may be harmful (1975, J. Am. Vet. Med. Assn. 167:540545) and as this was a wild animal which was improving it was not considered worth the risk to expose it to an extensive diagnostic work-up.

Recent improvements in delivery of supportive care and new behavioral techniques which allow routine diagnostic procedures to be carried out with little or no stress associated have greatly improved preventive medicine and early diagnosis of captive marine mammals (1984, Proc. Int. Aquatic Animal Med. Assn. 1:55-56).

Acknowledgments

The authors acknowledge Dr. R. George Bailey, the staff of the Miami Seaquarium, and the park ranger staff of Everglades National Park for their extensive efforts and technical assistance.

References

1.  White, JR. Thiamine deficiency in an Atlantic bottlenose dolphin (Tursiops truncatus) on a diet of raw fish. J Am Vet Med Assn 1970; 157(5):559-562.

2.  Sweeney, JC, Ridgway, SH. Procedures for the clinical management of small cetaceans. J Am Vet Med Assn 1975; 167:540-545.

3.  Sweeney, JC. Behavioral techniques for preventive medicine in marine mammals. Prop Int Assn Aquatic Animal Med 1984; 1(l):5556.