Table 1 Pathological and histopathological lesions [16, 77, 222, 241, 243]

Liver

Enlarged with marked lobular pattern, yellow-grey colour, brittle, circumscribed infiltration with granulocytes, degenerative alterations of hepatocytes compatible with apoptosis (extensive vacuolization, severe alterations in the mitochondrial structure, karyopyknosis and karyolysis) activation of Kupffer cells, leukopenia

Trachea

Hyperaemia of mucous membrane, petechial or diffuse haemorrhages, may be filled with bloody foam

Lung

Hyperaemia, pulmonary oedema, intra-alveolar and perivascular haemorrhages, sometimes slight catarrhal bronchiolitis, proliferation of lymphocytes

Kidneys

Enlargement with spotted dark red coloration, hyperaemia, haemorrhages within glomerular loops and renal medulla, hyaline thrombi, dilated tubuli, lymphocytic infiltration, degeneration of tubular epithelium

Spleen

Enlargement (splenomegaly), spotted dark red colorations, hyperaemia, occasionally karyorrhexis within follicles, hemosiderosis, leukopenia

Digestive tract

Contents usually normal, occasional enteritis, subserous haemorrhages

Chest and abdominal cavity

Small amounts of serous, occasionally bloody exudate, sometimes subserous haemorrhages

Muscles

Anaemia in the area of the thighs, petechiae in the heart muscle, focal necrosis in myocardium, degenerative alterations, hemosiderosis

Central Nervous System

Congestion of cortical vessels, dilated vessels in the area of the pia mater of the cortex and cerebellum, hyperaemia, small haemorrhages in the cortex, occasionally non-purulent encephalomyelitis with lymphocytic infiltration