Total anomalous pulmonary venous connection in a chicken.

This report describes a case of total anomalous pulmonary venous connection (TAPVC) in a 5-wk-old male white leghorn chicken that presented with growth retardation. This chicken was a specific-pathogen-free chicken bred in an isolator. At 5 wk of age, the chicken was euthanatized and autopsied. Macroscopically, the right ventricle and right atrium were significantly enlarged whereas the left atrium was small and blind-ending with no connection to the pulmonary veins. The pulmonary veins were connected directly to the right atrium. The above abnormality was accompanied by an ostium secundum-type atrial septal defect. No other malformations were observed. TAPVC is a very rare congenital cardiac abnormality that has not been reported in avian species to date.

Immunoreactivity and morphological changes of bursal follicles in chickens infected with vaccine or wild-type strains of the infectious bursal disease virus.

Infectious bursal disease (IBD) is characterized by immunosuppression due to the depletion of lymphocytes in the atrophied bursa of Fabricius (BF). We have sometimes encountered contradictory findings: chickens infected with the vaccine IBD virus (IBDV) strain have sometimes exhibited a highly atrophied BF, but not immunosuppression. In this study, chickens administered vaccine or wild-type strains of IBDV were later vaccinated with the B1 strain of the Newcastle disease virus (NDV). Bursal changes were examined histologically with a focus on the bursal follicle. The immunoreactivity to NDV was also evaluated with the hemagglutination inhibition test. In gross examination, we observed a few chickens with a severely atrophied BF in vaccine strain-administered groups (vaccine groups), and the level of severity was the same as that in the wild-type strain-administered group (wild-type group). However, these chickens retained humoral antibody responses to NDV and were revealed to possess a higher number of bursal follicles than those of the wild-type group. These results indicated that macroscopic evaluation dose not accurately reflect the immunoreactivity and degree of bursal damage in IBDV-administered chickens. We also found non-immunosuppressed chickens in the wild-type group. These non-immunosuppressed chickens retained a significantly higher number of normal follicles and total follicles according to our statistical analysis. Furthermore, a high correlation coefficient between the NDV-HI titer and the number of normal follicles was found in the wild-type group. These results implied that the retained number of normal follicles is important for the immunoreactivity of chickens infected with IBDV.