Morphological Investigations of Experimental Acute Intoxication with the Anticoagulant Rodenticide Bromadiolone in Pheasants

Morphological investigations were performed to observe the changes after experimental acute intoxication with the anticoagulant rodenticide bromadiolone in pheasants. The study was performed with 8 groups of pheasants treated with increasing doses of the tested preparation: 5 mg/kg (group I), 10 mg/kg (group II), 20 mg/kg (group III), 30 mg/kg (group IV), 40 mg/kg (group V), 50 mg/kg (group VI), 60 mg/kg (group VII) and 70 mg/kg (group VIII). All birds from groups I to V have survived the intoxication whereas those from groups VI, VII and VIII have died. During the intoxication, inappetence, accelerated and difficult breathing, adynamia, watery blood discharge from the beak were observed. All pheasants with fatal outcome and the survivors, which were euthanized after the experiment (day 20) were necropsied and gross changes in the liver, the lungs and kidneys were described. Liver alterations varied from strong hyperaemia and activation of the monocytic-macrophageal system to diffuse vacuolar or granular parenchymal dystrophy, as well as necrobiotic to necrotic changes, intra- and inter-lobular haemorrhages, perivascular mononuclear proliferations and bile duct hyperplasia. Lungs exhibited congestive hyperaemia, oedema in the interstitium and the mucous coats of bronchi and parabronchi, desquamation of epithelial cells in bronchioles and lung parenchymal haemorrhages. In the kidney parenchyma, congestive hyperaemia and haemorrhages were seen, varying within a broad range from karyolysis and karyopyknosis in epithelial tubular cells to cellular desquamation and disintegration and necrosis. All observed changes in parenchymal organs were dose-related, being more pronounced in pheasants treated with higher doses of the tested rodenticide.