Population-level laterality in foraging finless porpoises

Fatal upper aerodigestive tract obstruction in an East Asian finless porpoise (Neophocaena asiaeorientalis sunameri): findings in post-mortem computed tomography

The present case report aims to outline the post-mortem findings of an East Asian finless porpoise with upper aerodigestive tract obstruction using different post-mortem computed tomography (PMCT) visualization techniques and discusses the potential cause of death of this individual. A dead-stranded adult male East Asian finless porpoise was recovered from the Northern coast of Jeju Island, Republic of Korea. The carcass was frozen in Jeju National University within 2 h upon first reported. The PMCT examinations were performed at 120 kVp, 200 mAs with a section thickness of 1 mm. The scan field of view (sFOV) was set to 400 mm. Four image rendering techniques, including multi-planar reconstruction, three-dimensional volume rendering, perspective volume rendering, and minimum intensity projection technique, were used to aid the diagnosis of upper aerodigestive tract obstruction in the stranded finless porpoise. Conventional necropsy was performed to provide a complete necropsy report. Using PMCT, a Sebastidae of 24 cm measured length was found to be lodged in the left pharyngeal food channel and esophagus of the finless porpoise. Hard rays of the pectoral fin of the lodged fish have impaled the esophageal mucosa. Fishing gear was found to embed at the dorsal side of the lodged fish. The trachea was compressed ventrally and the arytenoepiglottic tube opening has been narrowed, which may precipitate to the finless porpoise difficult breathing. Pulmonary hyperinflation, pulmonary edema, pneumothorax, pneumopericardium, and pneumorrhachis were observed. This case report represents the first documentation of potential radiological indicators of upper aerodigestive tract obstruction in the East Asian finless porpoise using PMCT. Spatial location of the lodged item could be rendered in situ as the time of death. It has demonstrated that PMCT could provide objective measurements to adjunct the necropsy findings in diagnosis of fatal aerodigestive tract obstruction in stranded cetaceans.

Show me your best side: Lateralization of social and resting behaviors in feral horses

Growing evidence shows a variety of sensorial and motor asymmetries in social and non-social interactions in various species, indicating a lateralized processing of information by the brain. Using digital video cameras on tripods and drones, this study investigated lateralization in frequency and duration of social behavior patterns, in affiliative, agonistic, and resting contexts, in a feral population of horses (Equus ferus caballus) in Northern Portugal, consisting of 37 individuals organized in eight harem groups. Affiliative interactions (including grooming) were more often performed, and lasted longer, when recipients were positioned to the right side. In recumbent resting (animals lying down) episodes on the left side lasted longer. Our results of an affiliative behavior having a right side tendency, provide partial support to the valence-specific hypothesis of Ahern and Schwartz (1979) - left hemisphere dominance for positive affect, affiliative behaviors. Longer recumbent resting episodes on the left side may be due to synchronization. However, in both instances it is discussed how lateralization may be context dependent. Investigating the position asymmetries of social behaviors in feral equids will contribute to a better understanding of differential lateralization and hemispheric specialization from the ecological and evolutionary perspectives.