Intestinal smooth muscle hypertrophy and hyperplasia has been described in human and several mammal species. In birds, only one case of intestinal smooth muscle hyperplasia has been reported. This paper describes the anatomopathological and histological findings of three cases of intestinal smooth muscle hypertrophy/hyperplasia in two different avian species belonging to the family Gallinidae and Columbidae. Grossly, it involved all tracts of the small intestine. Histologically, hyperplasia involved the mucosal villi, muscularis mucosa and inner and outer layers of the tunica muscularis. Hypertrophy was apparently detected only in the inner circular muscle layer. Lack of submucosal plexuses was also observed in all three animals. The results confirm the remarkable histological difference between mammals and avian species and show as these pathological changes can occur in different species of birds.
Keywords: intestine; ornamental chicken; ringdove pigeon; smooth muscle hyperplasia.