RESUMO
In a dairy herd of 21 cows which were on pasture during the day at the end of May 2002, four eight years old cows were suddenly inappetent and showed severe diarrhoea consisting of black discolorate feces. A few days after the onset of the disease, three affected cows exhibited neurological disorders. These cows were admitted to the IInd Medical Clinic of the University for Veterinary Medicine in Vienna. Following clinical signs were observed: circulatory weakness, anorexia, atony of the rumen, diarrhoea and in accordance with acute lead poisoning typical signs of the central nervous system. One cow died and the other two animals were euthanized. Results of blood testing were anaemia, basophil spotting of erythrocytes, increase of liver enzymes and CK, hypocalcaemia, decrease of potassium and phosphate. The cerebrospinal fluid of two cows showed increased CK-, LDH- and AST-values. The lead contents of whole blood samples were between 0.486 and 0.928 mg/kg, of liver samples 13.3 to 114.4 mg/kg, of kidney samples 172.2 to 448 mg/kg and of rumen content 59 mg/kg fresh matter. At necropsy, enteritis, liver fluke disease and severe interstitial and alveolar pulmonary emphysema were found. Pathohistologically typical ischaemic necrosis of neurons predominantly at the tips of the gyri, disseminated petechial hemorrhages and moderate diffuse neovascularisation, but no acid-fast intranucleolar inclusion bodies in the renal tubules were observed. As causative agent of the acute lead poisoning a residue on combustion, taken up by the cows on the pasture, was confirmed. The ash residue was formed by combustion of three tires which contained 450 g heavy weights of 96.5% lead for wheel balance. The lead content of the ash residue was between 2.9 and 28 g/kg dry matter.