A study of the pathogenesis of cardiac lesions in gnotobiotic chickens infected experimentally with Mycoplasma synoviae

Abstract

The pathogenesis of cardiac lesions associated with Mycoplasma synoviae-infection in gnotobiotic chickens was studied. Three separate groups, consisting of 24, 23 and 25 gnotobiotic chickens, were hatched from specific-pathogen-free eggs and maintained in plastic-film, controlled-environment isolators using techniques for handling germfree animals. When two-weeks-old, each chicken in Group I was injected in the left foot pad with 10 times the EIDâ‚…â‚€ of a yolkallantoic culture of Mycoplasma synoviae. Each chicken in Group II was given 10,000 times the EIDâ‚…â‚€ at the same time. Chickens in Group III served as uninfected controls. Separate groups of 4 chickens from Group I, 2 to 5 chickens from Group II and 4 to 5 chickens from Group III were killed 5, 10, 15, 20, 25 and 30 days postinoculation. Specimens were collected from each chicken on each sampling day for hematology, enzymology, gross pathology, histopathology, electron microscopy, microbiology and serology. Data from these various studies were used to formulate a hypothesis on the pathogenesis of cardiac lesions and to evaluate the sequential development and nature of other lesions in infected chickens. A severe anemia, which was characterized as hemolytic, macrocytic and normochromic to hypochromic, developed in infected chickens. Anemia was more severe in chickens from Group II. Infected chickens had a leucocytosis due to heterophilia and monocytosis. Infected chickens had a cardiomegaly and the magnitude of the increase in relative heart weight was correlated with the increase in severity of the anemia..