Pathological and toxicological investigations of concomitant cyanide and nitrate/nitrite poisoning in Murrah buffaloes associated with feeding of Zea mays and Sorghum bicolor

Three adult female Murrah buffaloes were presented with a history of consumption of young shoots of maize and sorghum. The animals exhibited signs of dyspnea, muscle tremors, ptyalism, tympany, diarrhea, and recumbency. Clinical examination revealed subnormal body temperature, tachycardia, tachypnea, and cherry red (hyperaemia/congestion), brownish to purple discoloration (cyanosis) of conjunctival, oral, and vulval mucous membranes. The blood samples from each animal were collected before the affected animals collapsed to death. Necropsy findings revealed dark red or chocolate-brown colored unclotted blood, pin-point hemorrhages in the epicardial surface, marbling appearance of lungs, hepatomegaly, distension of gall bladder, and congestion of blood vessels in the subcutaneous tissues and ruminal wall. Toxicological studies confirmed the presence of cyanide as well as nitrate/nitrite in rumen contents. Liver and kidney samples also were positive for nitrate/nitrite. Hemogram showed anemia as evidenced by significantly lower hemoglobin and total erythrocyte count values. Serum biochemical profile was altered with a significant elevation in aspartate transaminase, alanine transaminase, creatine kinase-MB, blood urea nitrogen, creatinine and potassium levels. In addition to upregulation of acute phase (ceruloplasmin) and stress hormone (cortisol) responses, concomitant cyanide and nitrate/nitrite poisoning in the buffaloes resulted in oxidative (elevated malondialdehyde and glutathione S-transferase) and nitrosative (elevated nitric oxide) stress. Histopathological examination revealed thickening of interlobular septa due to congestion, hemorrhages and edematous fluid in lungs, along with marked congestion, hemorrhages, and degenerative changes in liver, kidneys, heart and brain. An insight into the pathological changes can help clinicians to diagnose and treat the poisoning cases more effectively.