Fatal tension pneumothorax secondary to verminous bronchopneumonia in a white-beaked dolphin: case report and brief literature review

Pneumothorax is reported infrequently in marine mammals, most often secondary to physical or barometric trauma. We describe tension pneumothorax associated with verminous bronchopneumonia in a juvenile white-beaked dolphin stranded in Québec, Canada. Autopsy findings included a violent escape of air upon opening the pleural cavity, and white nematode-filled cystic nodules extending into the subpleural space and the lung parenchyma. One of these cysts had ruptured on the pleural surface. Numerous nematodes were observed in the lumen of main and secondary bronchi. Mediastinal lymph nodes were also enlarged. Helminths were collected and processed for molecular species identification. Histologically, verminous bronchopneumonia was marked by massive infiltration of the airways by polymorphonuclear and histiocytic cells surrounding adult and larval nematodes. Regional lymph nodes also contained focal infiltrates of polymorphonuclear cells associated with larvae. The nematodes were identified as <i>Halocercus lagenorhynchi</i> according to their morphology and molecular characterization. We attributed the death of this dolphin calf to tension pneumothorax secondary to a massive infection by the lungworm <i>H. lagenorhynchi</i>.