An ion chromatographic method was used to simultaneously determine nitrate and nitrite ions in biological samples. Ultrafiltration was used to produce a protein-free filtrate. Chloride interferences were eliminated by precipitation as the silver salt. Detection limits and average recoveries were 0.5 mg/L and 102% for nitrate and 0.2 mg/L and 78% for nitrite, respectively. Nitrate concentration was 2.1 +/- 1.8 mg/L and 4.9 +/- 0.8 mg/L in serum and ocular fluid of healthy cattle, respectively; nitrite was not detected. A severe case of nitrate poisoning in cattle was described and used to study the concentrations of nitrate and nitrite in samples obtained under natural conditions. Nitrate concentration of acutely poisoned cattle was 35% lower in ocular fluid at 158.1 +/- 51.4 mg/L, than in serum at 256.3 +/- 113.4 mg/L. Nitrite was not detected, because of the long processing time (> 3 hours) required for samples obtained in the field. A gradual decrease in ocular fluid nitrate of 29.4% at 24 hours, 25.9% at 36 hours, 51.6% at 48 hours, and 73.2% at 60 hours was observed; however, concentrations remained diagnostically significant (73.2 mg/L) 60 hours after death. Twenty-four hours after poisoning, the serum nitrate concentration of severely ill (52.7 +/- 51.9 mg/L) and moderately affected (12.4 +/- 5.7 mg/L) cattle that survived was indicative of the severity of clinical signs previously observed. Nitrate in serum and ocular fluid was stable in samples stored for 24 hours at 23 C, 1 week at 4 C, and 1 month at -20 C.

This article reports cases of nitrate poisoning in Indian indigenous cattle breeds comprising two Gir cows aging 4 years each, and one Barugur cow at 1.5 years of age. The cattle with case history of sudden death and oozing of partially clotted blood from the anal opening were brought to the Central University Laboratory (CUL), Center for Animal Health Studies (CAHS), Tamil Nadu Veterinary and Animal Sciences University (TANUVAS) for diagnostic investigation with a suspicion of anthrax. According to anamnesis, all the animals were clinically normal and did not reveal any abnormality on the previous day. The animals were fed with recently harvested sorghum leaves and stalks. Smears examined for anthrax were found negative. Biological test (mice inoculation) for anthrax was also negative. Gross lesions on necropsy examination of the carcases were suggestive of nitrate intoxication. Finally, nitrate intoxication of these cattle was confirmed by chemical and toxicological analysis of fodder, rumen content, aqueous humor, liver, kidney and urine.

In order to clarify the pathogenesis of perirenal edema, pigs and rabbits were administered with oxalate and nitrate, with oxalate nitrate and glycolic acid, with oxalate, nitrate and ascorbic acid and with oxalate, nitrate and calcium, respectively. The pigs and rabbits administered with oxalate and nitrate with oxalate, nitrate and glycolic acid and with oxalate, nitrate and ascorbic acid, respectively, were not showed perirenal edema despite of observing the abundant oxalate crystals in the proximal convoluted tubles