Treatment of nitrate intoxication in a cow

Nitrate poisoning was induced in a cow by giving it 200 g potassium nitrate through a rumen fistula for three to four days in succession. The effect of treatment with methylene blue, ascorbic acid and menadione, administered intravenously in different dosages was assessed by measuring methaemoglobin as a percentage of total haemoglobin and comparing the results with those from the untreated cow. The results obtained indicate that ascorbic acid and menadione are unsuitable for treatment of methaemoglobinaemia in nitrate poisoned cattle, but treatment with methylene blue at 1 mg/kg body weight appears to be adequate.