Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation
Abstract Background Marine mammals act as sentinel species, with top predators’ overall health reflecting their ecosystem, integrated across multiple trophic levels. Yet apparently healthy wild animals may have significant subclinical pathology that goes undetected due to unknown medical histories....
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BMC
2025-04-01
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| Series: | BMC Veterinary Research |
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| Online Access: | https://doi.org/10.1186/s12917-025-04740-w |
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| author | Michelle R. Shero Kathy Burek-Huntington Robert McCorkell Steven A. Nadler Caroline L. Rzucidlo Amy C. Klink Allyson G. Hindle Jennifer M. Burns Shawn Johnson |
| author_facet | Michelle R. Shero Kathy Burek-Huntington Robert McCorkell Steven A. Nadler Caroline L. Rzucidlo Amy C. Klink Allyson G. Hindle Jennifer M. Burns Shawn Johnson |
| author_sort | Michelle R. Shero |
| collection | DOAJ |
| description | Abstract Background Marine mammals act as sentinel species, with top predators’ overall health reflecting their ecosystem, integrated across multiple trophic levels. Yet apparently healthy wild animals may have significant subclinical pathology that goes undetected due to unknown medical histories. Marine mammals, particularly phocid seals, often suffer from heavy parasite burdens. While there are documented cases of severe respiratory infections resulting in complications during sedation, there have been no reports of gastrointestinal parasites contributing to poor outcomes during examinations requiring sedation or anesthesia. This report describes two unique presentations of high intestinal parasite loads that purportedly predisposed Weddell seals (Leptonychotes weddellii) to complications under sedation, and characterizes underlying pathology. Case presentation Two adult female Weddell seals exhibited prolonged apnea and vomiting while under intravenous sedation, that led to aspiration and mortality despite resuscitation attempts. Post-mortem examination revealed a severe Diphyllobothrium tapeworm impaction in the duodenum, with the parasitic mass causing a partial or complete obstruction. In both cases, the stomach was remarkably distended, suggesting the parasitic mass slowed gastric emptying. Both animals’ stomachs contained a high parasite burden with roundworms embedded into the mucosa. Histological analysis identified underlying pathological conditions that were likely parasite related, including chronic pneumonia associated with lungworm infestations, reactive, depleted and fibrosed lymph nodes, granulomatous lymphadenitis and hepatitis. Further examination in one of the animals revealed severe gastritis and necrotizing duodenitis at the site of the cestode infection. Conclusions To our knowledge, this is the first description of a significant gastrointestinal parasitic impaction being linked to acute distress during sedation in a marine mammal. We provide an in-situ depiction of the severe cestode infection. It is noteworthy that both animals in this case study exhibited histopathology consistent with chronic inflammation across multiple organ systems. Whether animals were sufficiently immunocompromised that rapid parasite growth became unchecked, or whether the parasite infestation led to dysfunction in other organs remains unresolved. We discuss the potential for premedication with prokinetic agents that increase esophageal sphincter tone to mitigate complications in future late-summer Weddell seal handlings. |
| format | Article |
| id | doaj-art-dfcff6da27ba4f259a750a117d4e9d7b |
| institution | OA Journals |
| issn | 1746-6148 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | BMC |
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| series | BMC Veterinary Research |
| spelling | doaj-art-dfcff6da27ba4f259a750a117d4e9d7b2025-08-20T01:47:32ZengBMCBMC Veterinary Research1746-61482025-04-0121111210.1186/s12917-025-04740-wNovel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedationMichelle R. Shero0Kathy Burek-Huntington1Robert McCorkell2Steven A. Nadler3Caroline L. Rzucidlo4Amy C. Klink5Allyson G. Hindle6Jennifer M. Burns7Shawn Johnson8Biology Department, Woods Hole Oceanographic InstitutionAlaska Veterinary Pathology ServicesFaculty of Veterinary Medicine, University of CalgaryDepartment of Entomology and Nematology, University of California DavisBiology Department, Woods Hole Oceanographic InstitutionSchool of Life Sciences, University of Nevada Las VegasSchool of Life Sciences, University of Nevada Las VegasDepartment of Biological Sciences, Texas Tech UniversitySea Change HealthAbstract Background Marine mammals act as sentinel species, with top predators’ overall health reflecting their ecosystem, integrated across multiple trophic levels. Yet apparently healthy wild animals may have significant subclinical pathology that goes undetected due to unknown medical histories. Marine mammals, particularly phocid seals, often suffer from heavy parasite burdens. While there are documented cases of severe respiratory infections resulting in complications during sedation, there have been no reports of gastrointestinal parasites contributing to poor outcomes during examinations requiring sedation or anesthesia. This report describes two unique presentations of high intestinal parasite loads that purportedly predisposed Weddell seals (Leptonychotes weddellii) to complications under sedation, and characterizes underlying pathology. Case presentation Two adult female Weddell seals exhibited prolonged apnea and vomiting while under intravenous sedation, that led to aspiration and mortality despite resuscitation attempts. Post-mortem examination revealed a severe Diphyllobothrium tapeworm impaction in the duodenum, with the parasitic mass causing a partial or complete obstruction. In both cases, the stomach was remarkably distended, suggesting the parasitic mass slowed gastric emptying. Both animals’ stomachs contained a high parasite burden with roundworms embedded into the mucosa. Histological analysis identified underlying pathological conditions that were likely parasite related, including chronic pneumonia associated with lungworm infestations, reactive, depleted and fibrosed lymph nodes, granulomatous lymphadenitis and hepatitis. Further examination in one of the animals revealed severe gastritis and necrotizing duodenitis at the site of the cestode infection. Conclusions To our knowledge, this is the first description of a significant gastrointestinal parasitic impaction being linked to acute distress during sedation in a marine mammal. We provide an in-situ depiction of the severe cestode infection. It is noteworthy that both animals in this case study exhibited histopathology consistent with chronic inflammation across multiple organ systems. Whether animals were sufficiently immunocompromised that rapid parasite growth became unchecked, or whether the parasite infestation led to dysfunction in other organs remains unresolved. We discuss the potential for premedication with prokinetic agents that increase esophageal sphincter tone to mitigate complications in future late-summer Weddell seal handlings.https://doi.org/10.1186/s12917-025-04740-wCestodeDuodenitisGastritisInflammationNematodeParasite |
| spellingShingle | Michelle R. Shero Kathy Burek-Huntington Robert McCorkell Steven A. Nadler Caroline L. Rzucidlo Amy C. Klink Allyson G. Hindle Jennifer M. Burns Shawn Johnson Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation BMC Veterinary Research Cestode Duodenitis Gastritis Inflammation Nematode Parasite |
| title | Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation |
| title_full | Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation |
| title_fullStr | Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation |
| title_full_unstemmed | Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation |
| title_short | Novel presentation and pathophysiology of heavy parasitic burdens in Weddell seals (Leptonychotes weddellii) during sedation |
| title_sort | novel presentation and pathophysiology of heavy parasitic burdens in weddell seals leptonychotes weddellii during sedation |
| topic | Cestode Duodenitis Gastritis Inflammation Nematode Parasite |
| url | https://doi.org/10.1186/s12917-025-04740-w |
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