Amoebosis in the flat-shelled spider tortoise (Acinixys planicauda)

Amoebosis is one of the most common protozoal diseases of reptiles, but has rarely been reported in tortoises. Six cases of amoebosis were identified in flat-shelled spider tortoises immediately after their importation from Madagascar to Japan. Necropsy revealed an extensive green pseudomembrane of ulceration along the length of the thickened wall of the colon, and disseminated green foci in the liver. Histologically, the colonic wall was severely ulcerated and covered with a fibrinonecrotic pseudomembrane, and many amoebic trophozoites were seen in the submucosa. Multifocal necrosis with intralesional amoebic trophozoites corresponded to the disseminated green foci in the liver. Amoebic trophozoites invaded many blood vessels in the colon and liver. All tortoises exhibited severe colonic lesions, but the severity of the hepatic lesions varied. These findings suggest that amoebic colitis was the primary lesion with spread of amoebae to the liver via the portal system.