Parasites and related pathological lesions in the gastrointestinal tract of a seal (Phoka vitulina Linnaeus).

An immature seal, about one-year-old, died a natural death. At autopsy, a large number of Contracaecum osculatum and Pseudoterranova decipiens, as well as some of Anisakis simplex were found in the stomach together with numerous Corynosoma strumosum in the small intestine and colon. Histopathological examination revealed epithelial desquamation, congestion and hemorrhage in the mucosa. There were cellular infiltration and fibroplasia around the nematodes, collapsed nematodes and molted nematode cuticules in the stomach wall. The small intestine and colon underwent severe epithelial desquamation, catarrhal inflammation, and slight inflammatory response consisting mainly of lymhocytes. To the best of our knowledge, this may be the first report on Corynosoma strumosum in Japan.