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The application of whole-body post-mortem computed tomography (PMCT) in veterinary and wildlife post-mortem research programs is advancing. A high incidence of pulmonary pathology is reported in the harbor porpoise ( Phocoena phocoena ). In this study, the value of PMCT focused on pulmonary assessment is evaluated. The objectives of this study were to describe pulmonary changes as well as autolytic features detected by PMCT examination and to compare those findings with conventional necropsy. Retrospective evaluation of whole-body PMCT images of 46 relatively fresh harbor porpoises and corresponding conventional necropsy reports was carried out, with a special focus on the respiratory tract. Common pulmonary PMCT findings included: moderate (24/46) to severe (19/46) increased pulmonary soft tissue attenuation, severe parasite burden (17/46), bronchial wall thickening (30/46), and mild autolysis (26/46). Compared to conventional necropsy, PMCT more frequently identified pneumothorax (5/46 vs. none), tracheal content (26/46 vs. 7/46), and macroscopic pulmonary mineralization (23/46 vs. 11/46), and provided more information of the distribution of pulmonary changes. These results indicate that PMCT adds information on pulmonary assessment and is a promising complementary technique for necropsy, despite the frequent presence of mild autolytic features.

Whale lice (Cyamidae; Amphipoda) are ectoparasitic crustaceans adapted to the marine environment with cetaceans as their host. There are few reports of cyamids occurring in odontocetes from the North Sea, and long-term studies are lacking. Marine mammal health was monitored along the German and Dutch coasts in the past decades, with extensive post mortem investigations conducted. The aim of this study was to analyse archived ectoparasite samples from stranded cetaceans from the North Sea (2010-2019), to determine species, prevalence and impact of ectoparasite infection. Ectoparasites were found on two cetacean species - harbour porpoises ( Phocoena phocoena ), as the most abundant cetacean species in the North Sea, and on a pilot whale ( Globicephala melas ), as a rare species here. Prevalence of ectoparasitic crustaceans in cetaceans was low: 7.6% in porpoises stranded in the Netherlands (n = 608) and 1.6% in porpoises stranded in Germany (n = 122). All whale lice infections were found on hosts with skin lesions characterised by ulcerations. Morphological investigations revealed characteristic differences between the cyamid species Isocyamus (I.) delphinii and I. deltobranchium identified. Isocyamus deltobranchium was determined in all infected harbour porpoises. I. delphinii was identified on only the pilot whale. Molecular analyses showed 88% similarity of mDNA COI sequences of I. delphinii with I. deltobranchium supporting them as separate species. Phylogenetic analyses of additional gene loci are required to fully assess the diversity and exchange of whale lice species between geographical regions as well as host specificity. Differing whale lice prevalences in porpoises stranded in the Netherlands and Germany could indicate a difference in severity of skin lesions between these areas. It should be further investigated if more inter- or intraspecific contact, e.g., due to a higher density of porpoises or contact with other cetaceans, or a poorer health status of porpoises in the southern North Sea could explain these differences., Competing Interests: Ethical standards: Ethical review and approval was not required for the animal study because all animals in our study were found dead, died naturally or were euthanized based on welfare grounds and none of the animals were killed for the purpose of this study. This publication was supported by 10.13039/501100001659Deutsche Forschungsgemeinschaft and 10.13039/501100005629University of Veterinary Medicine Hannover, Foundation within the funding programme Open Access Publishing., (© 2021 The Author(s).)