Poisoning by Cestrum laevigatum Schlecht., the cause of cattle losses in the State of Rio de Janeiro

Abstract

This study was initiated to determine the cause of certain cattle deaths in the State of Rio de Janeiro. These deaths have characteristic features and are observed principally during the dry season. A preliminary diagnosis of plant poisoning was made. Twenty-one field cases of the supposed plant poisoning were studied. Farms where mortalities had occurred were visited and the local management and feeding conditions, and the possible presence of poisonous plants on the pastures were assessed. Case histories were reviewed, post-mortem examinations and histopathological studies made. The symptomatology of the field cases were apathy, lack of appetite, muscle twitching, nervousness, agressivity and swaying gait. Death occurred, usually within 24 hours, exceptionally within three days after the first symptoms had appeared. Post-mortem lesions most commonly seen were a nutmeg appearance of the cut surface of the liver and dryness of the contents of the omasum and the large bowel. The contents of the large bowel were covered with mucus and frequently with blood. There were also petequiae, ecchymoses and suffusions, mostly in the serous membranes and the endocard. Sometimes these occurred in the subcutaneous, intermuscular and peritracheal connective tissue, less frequently in the mucosa of the gall bladder, larynx, trachea, bronchi and the gut. In a few cases there was edema of the gall bladder wall (Table 1) Histopathologic changes usually consisted of a severe liver distrophy, characterized by centrolobular necrosis with congestion and hemorrhages. Frequently there was vacuolization of the liver cells at the periphery of the lesion. Also seen were neutrophiles in the sinusoides, Kupffer cell activation, lymphocytic infiltration in the portal space and bile duct proliferation. (Table 3) Plants suspected to be poisonous were fed to yearling calves. Clinical observations were made on these animals and in case of death post-mortem examinations and histopathological studies performed. Of all the plant species experimentally studied, only one, Cestrum laevigatum Schlecht., caused poisoning with the same clinical and pathological picture seen in the field cases. (Table 4, 5, 6 and 7). The results of these experiments are discussed and the symptoms of experimental poisoning by C. laevigatum and of spontaneous poisoning compared. It was concluded that these cattle deaths in the State of Rio de Janeiro were caused by Cestrum laevigatum Schlecht.