Table 2 Summary of histopathology

No significant changes observed in any tissues examined.

Acute damage only to the olfactory organs including various inflammatory, degenerative, metaplastic, and necrotic lesions extending from the nasal cavity to the lungs. Intranasal lesions include olfactory epithelium necrosis (5 L, 5 M, 5H), lymphocytic inflammation (3 L, 4 M, 4 H), reactive hyperplasia (0 L, 0 M, 1 H), and olfactory lamellae fusion (0 L, 1 M, 3 H).

Acute damage only to the gills, intestine, and pharynx. Gills exhibited multifocal lesions consisting of lamellar fusion (4 L, 4 M, 5 H), epithelial hyperplasia (3 L, 4 M, 5 H), mononuclear cell infiltration (1 C, 4 L, 4 M, 5 H), epithelial necrosis (0 L, 4 M, 5 H), presence of thrombi in vessels (0 L, 4 M, 3 H) and hemorrhage (0 L, 2 M, 3 H). Intestine exhibits moderate to moderately severe atrophy of the mucosal folds (5 L, 5 M, 5 H), mild mononuclear infiltration of the lamina propria (5 L, 5 M, 5H) and mild necrosis of mucosal epithelium (2 L, 3 M, 3 H). Pharynx exhibits epithelial atrophy characterized by decreased mucosal thickness and loss of mucous secreting cells; also accompanied by mononuclear cell infiltration (0 L, 2 M, 4 H). Necrosis of pharyngeal epithelium occurred in 1 H.