Abstract

Since 1989/1990, after the first phocine distemper virus (PDV) epidemic, the state of Schleswig-Holstein, Germany, has financed a marine mammal stranding network. In German waters, there are only three indigenous marine mammals: harbor seal (Phoca vitulina), gray seal (Halichoerus grypus) and harbor porpoise (Phocoena phocoena). The animals are brought to the Research and Technology Center Westcoast (FTZ) in Büsum, an affiliation of the University of Kiel, where necropsies are conducted. The aim of pathology is the understanding of the health status in the frame of basic research, monitoring and applied research. The dissections were carried out according to Siebert et al. (2001)¹ and continual investigations were performed (e.g., histology, bacteriology, virology, toxicology, genetics, reproduction, age determination). In animals from German waters, the most affected organ seemed to be the lung. Emphysema and bronchopneumonias were found frequently, often in conjunction with parasitic infestation. In seals, acanthocephalans but also tapeworms cause irritation in the intestine. Young animals are also especially susceptible to severe hemorrhagic enteritis, whereas in older seals displacement of the intestine is a frequent cause of death. Small external wounds led to severe suppurative inflammation and were destructive to tissue and muscle. Cause of death often is identified as septicemia. Many potential pathogenic bacteria have been isolated in the blood and tissue samples (e.g., Brucella pinnipedia and B. cetacea, Clostridium perfringens, α- and β- hemolytic streptococci, Erysipelothrix rhusiopathiae). The most destructive disease in German waters, however, has been PDV. In 1988 and 2002, an epidemic of PDV affected 60% and 50%, respectively, of the Wadden Sea harbor seal population (The Netherlands, Germany, Denmark). The most prominent clinical symptoms were low energy to apathy, nasal discharge, dyspnoea, and swelling of neck and thorax. Histologically, marked alveolar edema and emphysema, lymphocytic depletion, and viral inclusion bodies in cells of various organs were detected. In 2007 the first case of morbilli virus antigen in a white-beaked dolphin (Lagenorhyncus albirostris) was reported. In January the moribund, subadult animal was found at the North Frisian coast of Germany.² Together with the two other stranding networks in Germany (Lower Saxony, Mecklenburg Western Pomerania), the FTZ has helped to understand and monitor the health status of harbor and gray seals as well as harbor porpoises in German waters and has contributed significant data to adjacent states.

Acknowledgments

The authors would like to thank the Ministry of Environment of Schleswig-Holstein for financing the stranding network and the many people who have helped at necropsies. Many thanks also to the Tierärztliche Hochschule Hannover and University of Giessen, Germany, for their technical support and help with further investigations.

References

1.  Siebert U, Wünschmann A, Weiss R, Frank H, Benke H, Frese K 2001. Post mortem findings in harbour porpoises (Phocoena phocoena) from the German North and Baltic Seas. J Comp Path 124:102-114.

2.  Wohlsein P, Puff C, Kreutzer M, Siebert U, Baumgärtner W 2007. Distemper in a dolphin. Emerging Infectious Diseases 13(12):1959-1961.