Pathological and Experimental Studies of Giant Facial Masses in Commercial Layer Hens

Abstract

Pathological and etiological field examinations were made to six commercial layer hens with giant facial masses from three farms. The masses in the field cases were diagnosed histologically as myxoma or fibrosarcoma (myxomatous type). In immunohistochemical terms, cellsfrom each tumor were positive for the groupspecific ALV antigen. Specific amplifications of subgroup A ALV genes obtained by means of the PCR method suggest that subgroup A ALV could play a part in tumor formation. Experimental studies were performed on two groups:(1) chickens inoculated with homogenates of tumor tissues from field cases and (2) verticallyinfected chickens hatched from eggs of chickens inoculated with tumor-tissue homogenates. Vertically infected chickens reproduced myxomas similar to those found in field cases, whereas inoculated experimental chickens did not.