Investigation and management of nitrate poisoning in cattle: a case study

Nitrate poisoning is generally caused by ingestion of high levels of nitrate containing fodder and it usually occurs in late autumn in Bangladesh, mainly during a flush growth of green grasses after a dry period. This case report was based on a suspected nitrate poisoning in two Holstein Friesian (2 years age, pregnant; 3.5 years age milking) cows in a commercial dairy farm at Hathazari, Chattogram. The cows had a history of feeding German grass from grassland that was flooded by a nearby fertilizer company’s wastewater and after 6 hours of feeding of that grass the animals were showing clinical signs of inappetite, diarrhoea, mild dyspnea and distended abdomen. The suspected fodder samples were brought to the Department of Physiology, Biochemistry and Pharmacology laboratory, Chattogram Veterinary and Animal Sciences University, Chattogram for toxicological testing. In diphenylamine test, we detected a high concentration of nitrate in the supplied fodder. However, we could not measure the plasma nitrate concentration of affected animals. The affected cows were treated with slow intravenous administration of 1% methylene blue (20mg/kg body weight) and ascorbic acid (15mg/kg body weight) for every 8 hours until completely remission of all clinical signs. In addition, cattle were medicated liver tonic (15 ml per animals) for a period of one week. Feeding of nitrate containing grass was restricted. After three days of treatment, the animals were recovered.