Occurrence and Pathological Characterisation of Lymphoid Leukosis in Crossbred Native Chicken

Abstract

Lymphoid leukosis (LL), a neoplastic disease caused by avian leukosis virus (ALV), continues to pose a major challenge to the poultry industry by reducing flock productivity and causing economic losses through mortality, reduced growth rate, and compromised egg production. The present study was undertaken to investigate the incidence and histopathological features of LL in crossbred native chickens maintained under organised farming systems. Eight representative carcasses of crossbred native chickens of varying ages were collected from organised poultry flocks. All carcasses underwent thorough postmortem examination, with detailed recording of gross pathological changes in visceral organs such as the liver, kidneys, spleen, and intestines. Microscopic examination was carried out using a compound light microscope to evaluate neoplastic changes in tissue specimens. Cytological smears were prepared from impression samples of tumorous lesions, fixed with methanol, and stained with Giemsa stain for evaluation of cellular morphology. Affected birds presented clinical signs of weakness, reduced feed intake, progressive weight loss, and mortality. Postmortem examination revealed hepatomegaly, splenomegaly, and tumour-like nodular growths in visceral organs. Histopathological analysis confirmed the presence of diffuse lymphocytic infiltrations, obliteration of normal organ architecture, and mitotic figures, which are characteristic hallmarks of lymphoid leukosis. Out of the eight carcasses examined, five (62.5%) were diagnosed with LL based on characteristic gross lesions, histopathological changes, and cytological findings. The findings not only establish the continued occurrence of LL in crossbred native chickens but also highlight the importance of histopathology in differentiating LL from Marek’s disease, which presents with overlapping gross lesions. This study underscores the relevance of continuous surveillance, routine diagnostic evaluation, and awareness among poultry farmers to reduce the risk of LL spread. Future research should focus on molecular detection of ALV strains, genetic resistance markers, and the development of effective breeding and management strategies to minimise economic losses associated with LL.