Abstract

Although obstruction of the upper respiratory tract due to choking by ingested prey,¹ neonatal aspiration pneumonia,² nasal papillomatosis,³ and other conditions, have sporadically been documented in wild stranded cetaceans, aspiration of foreign bodies, with presumptive laryngospasm and asphyxiation is not commonly recognized. On June 6, 2010, a two year old beluga at the Vancouver Aquarium developed an acute onset of inappetance. She had had no prior significant medical concerns. The calf was anorexic, but active and responsive to trainers. On June 13 (day 7) the animal was examined and samples, including gastric wash, collected and the calf treated with diazepam, prednisone and amoxicillin. Laboratory results proved within reference limits. Anorexia ensued for 3 days and follow up clinical pathology disclosed mild anemia and normal white blood cell counts. Clinical pathology findings from blood drawn June 16 and 18 revealed moderate inflammatory changes with initial lymphocytosis, then neutrophilia. Medications were adjusted to amoxi-clavulenic acid, diazepam, itraconazole and prednisone and following improvement in demeanour and resumed nursing was noted. On June 22, the animal succumbed. The most salient findings on necropsy were 2 small stones and a coin lodged within the ventrolateral diverticulae of the larynx with reactive respiratory mucosa and massive pulmonary edema. Histopathology revealed mucosal hyperplasia with scattered submucosal neutrophilic infiltrates and edema fluid. Pebbles and stones are commonly encountered within the stomach of hunter harvested beluga with no attendant pathology. The abrupt transition from the more oblique to horizontal orientation of the larynx and trachea and dilations of the lateral aspects may have predisposed this site to impact and lodging of ingested, regurgitated and subsequently aspirated foreign material. It is difficult to resolve if the foreign bodies were consumed concurrently or intermittently over a period of time. It is believed that ultimately, physical irritation may have been sufficient to have resulted in laryngospasm, asphyxiation and ultimate death of this animal.

References

1.  Byard RW, Tomo I, Kemper CM, Gibbs SE, Bossley M, Machado A, Hill M. Unusual causes of fatal upper aerodigestive tract obstruction in wild Bottlenose dolphins (Tursiops aduncus). Forensic Sci Med Pathol 2010; 6(3): 207–210.

2.  Makara M, Shimada A, Kawamura N, Murase T, Morita T. Aspiration pneumonia as a cause of neonatal death in three captive bottlenose dolphins (Tursiops truncatus). J Vet Med Sci 2007; 69(3): 325–327.

3.  Mignucci-Giannoni AA, Rosario-Delestre RJ, Alsina-Guerrero MM, Falcón-Matos L, Guzmán-Ramírez L, Williams EH, Bossart GD, Reidenberg JS. Asphyxiation in a Bottlenose dolphin (Tursiops truncatus) from Puerto Rico due to choking on a black margate (Anisotremus surinamensis). Aqua Mamm 2009; 35(1): 48–54.