Radiological Investigation of Gas Embolism in the East Asian Finless Porpoise (Neophocaena asiaeorientalis sunameri)

Abstract

Cetaceans have long been considered biologically adapted to suffer no adverse effects from diving-related tissue gas tension. However, increasing reports of gas embolism in cetaceans inhabiting European, Mediterranean and American waters have challenged the conventional understanding of marine mammal diving physiology. In human hyperbaric medicine, virtopsy techniques such as post-mortem computed tomography (PMCT) facilitate the visualization of gas embolism and could be performed adjunct to conventional autopsy. This research presents the first case of gas embolism identified in an East Asian finless porpoise inhabiting Asian waters. Massive gas embolic lesions were found in the liver, which had been compressing both the lungs and abdominal organs, and signs of pneumonia and parasitic infection were observed in both lungs. It is hypothesized that this porpoise might have been unable to expel in vivo gas bubbles from its circulation due to pulmonary dysfunction. Consequently, gas bubbles agglomerated in the liver, resulting in the development of gas embolic lesions. The findings of the present study provide insights into the occurrence of gas embolism in the East Asian finless porpoise, highlighting the potential of PMCT as a promising tool for the diagnosis of gas embolism in stranded cetaceans.

First report of kyphoscoliosis in the narrow‐ridged finless porpoises (Neophocaena asiaeorientalis): Findings from congenital and degenerative cases comparison using post‐mortem computed tomography

“…The NFPs inhabit the east Asian coast, a geographic hotspot of anthropogenic threats (Walther et al., 2020; Xiong et al., 2018; Yuen et al., 2023). Rapidly growing anthropogenic activities are influencing NFPs in this area.…”

“…Kyphoscoliosis in cetaceans is typically reported through in situ visual assessments during photo-identification field studies (Bertulli et al, 2015), and more subtle abnormalities are discovered during necroscopic examinations (DeLynn et al, 2011). As part of the pioneering stranded cetacean imaging programme in the Republic of Korea, NFPs stranded in Korean waters have been routinely assessed using post-mortem computed tomography (PMCT) to provide initial screening and supplementary evidence for conventional necropsy (Yuen et al, 2022(Yuen et al, , 2023. This case report presents the first documented cases of congenital, degenerative and traumatic kyphoscoliosis in two NFPs using PMCT.…”

Adhesive Bowel Obstruction (ABO) in a Stranded Narrow-Ridged Finless Porpoise (Neophocaena asiaeorientalis sunameri)

“…However, in the case of a dead organism, obtaining information regarding clinical symptoms becomes impossible. In the present study, our group adopted the PMCT workflow and imaging parameters with reference to Yuen et al [9,10] for the diagnosis of abdominal gas embolism and upper aerodigestive tract obstruction. We found that mesenteric fibrosis was a significant radiological sign to propose the presence of intestinal adhesion, which was confirmed via necropsy.…”

“…Consequently, the underlying pathogenesis of this disease in cetaceans is still not fully understood. To seek better understanding of the causes of death and underlying pathology, cetaceans stranded in South Korean waters have been routinely assessed using post-mortem computed tomography (PMCT) to provide additional information complementing the findings of conventional necropsy [9,10]. In this case report, we present a case of ABO in a stranded narrow-ridged finless porpoise and demonstrate the relevant necropsy and PMCT findings.…”