Abstract   

    Study was conducted to determine the incidence and gross pathological changes in different visceral organs of naturally affected chicken layers with spirochaetosis from July to October 1997 in the surrounding of Hyderabad. Out of 73, 12 poultry farms were found affected with spirochaetosis which indicated 16.4 per cent infection. Gross pathological changes observed in spleen and liver were most consistently involved. Spleens were enlarged from 3-6 times of its normal size with mottling appearance. Enlargement, congestion and discolouration were the main gross lesions in livers. In some cases kidneys were congested and swollen slightly and intestinal mucosa with haemorrhagicpatches in few of the cases.    

Key words: Spirochaetosis, layers, gross pathological lesions.