Pathology of benzalkonium chloride toxicity and its effect on body weight gain in broiler birds

Four groups comprising 16 broiler birds each were given benzalkonium chloride (BC) at 100, 300, 500 and 700 ppm in drinking water for 40 days and one group of 16 birds (control) was kept on plain water. Clinical signs in higher dose groups were respiratory distress, drooling of saliva, difficulty in deglutition, inappetence, apathy, lethargy and loss of body weight. Better body weight gain was recorded in 100 ppm dose rate. At 300 ppm, no significant body weight variation was recorded, whereas, at 500 and 700 ppm dose rates, significantly poor body weight gain was recorded. Major pathological changes were seen in 500 and 700 ppm groups, which exhibited formation of yellow diphtheritic plaques in the buccal cavity, swollen and pale commissures of beak and shortening of tongue. Minute necrotic and ulcerative foci were seen in oesophagus and crop. Hyperplastic and hypertrophic alterations were seen in mucosa of the upper digestive tract. Crop of 300 ppm group revealed formation of well developed epithelial nest with pseudoepitheliomatous hyperplasia at the margin of the lesion. Serum alanine transaminase, urea and uric acid in 500 and 700 ppm groups were elevated whereas no significant variations were observed in the 100 and 300 ppm groups. BC could enhance performance of broiler birds at 100 ppm dose rate. It should not be used beyond 300 ppm.