Unusual causes of fatal upper aerodigestive tract obstruction in wild Bottlenose Dolphins (Tursiops aduncus).

Necropsy examination of dolphins living in Gulf St Vincent, Australia is routinely undertaken to enable the evaluation of disease processes and to provide rapid medicolegal assessment of any inflicted and/or accidental injuries. Two Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) are reported to demonstrate conditions that may result in unexpected death involving upper airway compromise by quite unusual mechanisms. In the first case an adult male was found with extensive soft tissue trauma suggesting human interaction. At necropsy, death was due instead to upper airway obstruction from an impacted Slender-spined Porcupine Fish (Diodon nichthemerus) in the posterior pharynx and upper esophagus. In the second case, an adult male dolphin was found to have died, following several weeks' illness, from upper airway obstruction due to extensive respiratory tract papillomatosis within the blowhole. Given the infectious etiology of this condition the local population will be monitored for similar lesions. These cases demonstrate rare causes of upper airway obstruction in wild dolphins that were identifiable only after detailed necropsy examination. The possibility of human involvement in the deaths could be excluded.

Cetacean café coronary.

The carcass of a young adult male Indian Ocean Bottlenose dolphin (Tursiops cf aduncus) was found floating in an estuary near Adelaide, South Australia. An autopsy revealed that death had been caused by obstruction of the upper aerodigestive tract by a 660 mm Cobbler Carpetshark (Sutorectus tentaculatus). Similar airway obstruction in humans while feeding has been termed café coronary syndrome. Although death may have merely resulted from over-enthusiastic feeding, the possibility of neurological impairment was considered, and limited toxicological analyses of tissues was undertaken. No increase in organochlorine pesticides was found, however the possibility of heavy metal poisoning was not excluded. Formal neuropathology was unable to be undertaken. When sudden death in other mammal species mimics cases that are found in humans, similar underlying mechanisms may be present.