Chronic nonchylous lymphatic pleural effusion in a bottlenose dolphin (Tursiops truncatus)

CASE DESCRIPTION A 19-year-old male bottlenose dolphin (Tursiops truncatus) presented with inappetence and avoidant behavior. CLINICAL FINDINGS Ultrasound revealed a large-volume left-sided pleural effusion, which was consistent with chronic nonchylous lymphatic effusion and mild chronic hemorrhage by cytology. Computed tomography identified ipsilateral rib fractures, atelectasis, nodular pleuritis, marginal lymph node enlargement, and suspected dilation of the thoracic duct and internal thoracic veins. Fifteen lipids were significantly higher in serum of the dolphin as compared with controls (n = 3) using nontargeted lipidomics. TREATMENT AND OUTCOME A series of thoracentesis procedures were performed. Follow-up CT demonstrated marked reduction in pleural effusion with persistence of thoracic duct dilation and mass-like areas of pleural thickening. Ultrasonographic resolution of pleural effusion occurred 14 months after presentation; however, recrudescence was noted 5 months later. Over a total of 24 months, 21.52 L of pleural effusion was removed. Despite the presence of pleural effusion, the patient was clinically stable during this time and quality of life was considered good on the basis of continuous animal welfare evaluations. Humane euthanasia was elected following acute clinical decline 27 months after initial diagnosis. Necropsy confirmed severe pleural effusion, chronic severe pleural fibrosis with chronic hemorrhage, and mediastinal fibrosis with entrapped lymph nodes and thymic tissue.

Automated summary

A 19-year-old bottlenose dolphin presented with inappetence and avoidant behavior. Treatment was administered to reduce the pleural effusion, but the condition eventually recurred and euthanasia was elected. Necropsy confirmed severe pleural effusion, pleural fibrosis, and mediastinal fibrosis in the dolphin.