Fatal asphyxia due to laryngeal displacement by large-sized prey in a Guiana dolphin (Sotalia guianensis), Brazil

Abstract

The Guiana dolphin (Sotalia guianensis) is a small odontocete distributed from Santa Catarina state, Brazil, to Honduras. Although it is currently considered “near threatened” by the International Union for Conservation of Nature, considerable knowledge on health and disease aspects of this species has been gained over the last decade. The main threats for the species are represented by multiple anthropic factors. Guiana dolphins feed on a variety of taxa, primarily teleosts, crustaceans, and cephalopods. Herein, we reported a case of severe laryngeal displacement and esophageal impaction with ulceration associated with a deglutted adult leatherjacket (Oligoplites sp.). This fish species is not a common prey item of Guiana dolphins’ diet. Severe upper aerodigestive compromise likely led to death by mechanical asphyxia (choke) in this dolphin. This report attested the occurrence of upper aerodigestive dysfunction due to overzealous feeding in Guiana dolphin and contributed to general knowledge on pathology of the species.

Macro and microanatomy of some organs of a juvenile male Ganges River dolphin (Platanista gangetica spp. gangetica)

“…appendages show that the dolphin was once a land animal. Similarly, the respiratory system of dolphins follows a similar pattern to terrestrial mammals (Mariani et al, 2020). However, to avoid aspiration while feeding, some adaptive changes, such as blowholes instead of the nostril, are present in dolphins.…”

Postmortem of a juvenile male Ganges River dolphin (Platanista gangetica spp. gangetica) in Bangladesh

“…Dolphins, irrespective of the region, commonly encounter infectious diseases, 16 verminous pneumonia, 16,25 acute underwater entrapment, 25,26 choking [27][28][29] and others such as pulmonary oedema, 15,16 vascular congestion, 16,30 gas embolism 16,31 and neoplasia. 16 To date, cases of Ganges River dolphin entanglement in fishing nets have been reported.…”

Spatiotemporal accumulation of fatal pharyngeal entrapment of flatfish in harbour porpoises (Phocoena phocoena) in the German North Sea

“…There are several single case reports of different odontocetes with fatal entrapment of fish coming from various parts of the world including one beluga whale ( Delphinapterus leucas ) in Alaska ( Rouse, Burek-Huntington & Shelden, 2018 ), two long-finned pilot whales ( Globicephala melas ) in the Netherlands ( IJsseldijk et al, 2015 ), two Indio-Pacific bottlenose dolphins ( Tursiops aduncus ) in Australia ( Byard et al, 2003 ; Byard et al, 2010 ), two common bottlenose dolphins ( Tursiops truncatus ) in the USA ( Watson & Gee, 2005 ; Mazzoil et al, 2008 ) and one in Puerto Rico ( Mignucci-Giannoni et al, 2009 ), two Guiana dolphins ( Sotalia guianensis ) in Brazil ( Domiciano et al, 2016 ; Mariani et al, 2020 ) as well as two harbour porpoises in the USA ( Scheffer & Slipp, 1948 ; Scheffer, 1953 ) and one in Belgium ( Haelters, Kerckhof & Jauniaux, 2018 ). So far, only one study conducted a retrospective evaluation over a 15-year period in two populations of common bottlenose dolphins of the Indian River Lagoon, Florida, USA ( Stolen et al, 2013 ) showing fatal entrapment of fish as the cause of death in 4% of the carcasses in one population, while no cases where observed in the other population.…”

“…So far, only one study conducted a retrospective evaluation over a 15-year period in two populations of common bottlenose dolphins of the Indian River Lagoon, Florida, USA ( Stolen et al, 2013 ) showing fatal entrapment of fish as the cause of death in 4% of the carcasses in one population, while no cases where observed in the other population. In many of these reports, the prey item was reported to be too large to swallow ( Byard et al, 2003 ; Watson & Gee, 2005 ; Mignucci-Giannoni et al, 2009 ; Domiciano et al, 2016 ; Rouse, Burek-Huntington & Shelden, 2018 ; Mariani et al, 2020 ). Other reports suggested that the spines of the prey species or unusual prey species accounted for the fatal obstruction ( Mignucci-Giannoni et al, 2009 ; Stolen et al, 2013 ; IJsseldijk et al, 2015 ; Haelters, Kerckhof & Jauniaux, 2018 ).…”