Dugongs (Dugong dugon), classified as vulnerable marine mammals, are increasingly impacted by infectious diseases, yet the role of septicemia and disseminated intravascular coagulation (DIC) in their mortality remains uncharacterized. This study aimed to investigate the pathological and microbiological features associated with an acute mortality event in a juvenile dugong during rehabilitation in southern Thailand. Comprehensive histopathological and microbiological analyses were conducted on tissue samples collected postmortem. Bacterial isolation and identification were performed using standard culture techniques and the VITEK-2 system. Histological examination revealed multisystemic lesions, including fibrin thrombi, hemorrhage, hepatocellular degeneration, pancreatic necrosis, lymphoid depletion, and neuronal damage. Oxidative stress and DNA damage were confirmed in brain tissues through immunofluorescence detection of 4-hydroxynonenal (4-HNE) and 8-hydroxy-2′-deoxyguanosine (8-oxodG). Achromobacter xylosoxidans, an opportunistic pathogen, was isolated from multiple organs, consistent with acute systemic infection. These findings represent the first evidence of septicemia-associated DIC in dugongs caused by A. xylosoxidans, highlighting a previously undocumented cause of mortality in dugongs. The results emphasize the role of opportunistic bacteria in triggering oxidative damage and coagulopathy and underscore the importance of early detection and targeted therapeutic strategies to improve survival in stranded or rehabilitated dugongs.

Polyparasitism is frequently documented in cetaceans; however, the pathological consequences of concurrent multispecies helminth infections and their associated tissue responses remain incompletely understood. This study characterized multispecies helminth infections in two live-stranded dolphins from the Andaman coast of Thailand, a spinner dolphin (Stenella longirostris) and a pantropical spotted dolphin (Stenella attenuata), using integrated postmortem, parasitological, molecular, histopathological, and immunohistochemical approaches. Both dolphins harbored helminths involving multiple organ systems. Pulmonary nematodes were identified as Halocercus delphini, while larval and intestinal cestodes were identified as Clistobothrium sp. and Tetrabothrius sp., respectively. The most prominent pathological alterations occurred in the respiratory tract and included chronic pyogranulomatous bronchopneumonia, airway epithelial injury, fibrosis, and pulmonary congestion associated with Halocercus infection. Additional parasite-associated lesions included chronic enteritis, cholangitis with biliary epithelial injury and ductular reaction, pancreatic inflammation, and localized inflammatory responses surrounding larval cestode cysts in the blubber and testis. Immunohistochemistry demonstrated extensive interleukin-4 (IL-4) immunoreactivity in affected pulmonary and intestinal tissues, whereas interleukin-10 (IL-10) was undetectable. Nitrotyrosine and heat shock protein 70 (HSP70) immunoreactivity were widely distributed across parasite-associated tissues, while caspase-3 immunoreactivity showed tissue-dependent patterns. Collectively, these findings demonstrate that multispecies helminth infections in stranded dolphins were associated with multisystem pathological alterations accompanied by inflammatory, oxidative/nitrosative stress, cellular stress, and apoptotic responses. These findings highlight the potential pathological significance of polyparasitism in stranded dolphins and support consideration of parasite burden and associated tissue responses during cetacean postmortem investigations.