author(s)
Jagmeet Kaur, Rajinder Singh Brar, Geeta Devi Leishangthem, Harmanjit Singh Banga and Nittin Dev Singh

abstract
The present study was conducted to diagnose infectious laryngotracheitis disease (ILT) using gross, histopathological, and immunohistochemical approaches. A total of 25 samples were collected from the four different poultry farms from Ludhiana and the nearby districts. Upon gross analysis of the necropsied birds, the relevant tissue samples such as trachea, larynx, lungs and air sacs were collected in 10% Neutral buffered formalin and were then processed for histopathological and immunohistochemical studies. Grossly haemorrhages in the trachea and larynx were observed. The accumulation of small amount of mucus in the lumen of nares, larynx and trachea was also observed. Pneumonic changes of congestion, consolidation and red hepatisation were noticed in both the lungs. Histopathologic picture revealed loss of cilia, presence of mucus, congestion, increase number of goblet cells and lymphocytic infiltration. Formation of multinucleated giant cells (syncytia) with the presence of intranuclear inclusions was also observed. In two representative cases (2/25, 8%) of one outbreak, ILT antigen were mainly detected in the nucleus of tracheal epithelial cells as well as in cilia of trachea. Further, reliability of various techniques employed was considered and positive correlation (r=0.958833) was emerged out with conventional pathological scoring. It was concluded that the trachea acts as an organ of choice for demonstrating ILTV antigen for specific diagnosis of disease using immunohistochemistry.