What types of lesions does duck cholera cause?

Duck cholera mainly presents as septicemic pathological changes, with grossly visible manifestations of petechial hemorrhages on the serous membranes and mucous membranes. The liver surface has pinhead-sized, grayish-white necrotic spots with neat edges; the spleen is enlarged with necrotic spots of varying sizes on its surface; hemorrhage in the coronary sulcus, endocardium, and epicardium and pericardial effusion; pulmonary congestion and hemorrhage; hemorrhage in the duodenal and rectal mucosa, and hemorrhage on the surface of the intraperitoneal, gastric, and mesenteric fat.

1. Peracute type

The peracute type dies quickly, and necropsy shows no obvious pathological changes.

2. Acute type

Acute cases have septicemia as the main change. Hemorrhage in the duodenum is the most severe, with severe acute catarrhal enteritis or hemorrhagic enteritis, and the intestinal contents contain blood; the liver is enlarged, lighter in color, slightly firmer in texture, with pinpoint-sized yellow or grayish-white necrotic spots scattered on the surface; the spleen is slightly enlarged and soft in texture; punctate or patchy hemorrhages are commonly seen under the epicardium or serosa, with pericardial effusion, occasionally mixed with fibrinous clots; pulmonary congestion with hemorrhagic spots on the surface, sometimes with pneumonia; the ovaries of laying ducks often show a loose appearance of mature follicles, with indistinct surface blood vessels.

3. Chronic type

The lesions of the chronic type vary depending on the organs invaded by the bacteria. Some show fluid accumulation in the nasal cavity and upper respiratory tract, while others accumulate turbid or caseous exudate in the joints and tendon sheaths. The ovaries of female ducks often undergo obvious changes, with irregularly shaped eggs and soft texture; sometimes a pale green egg can be seen, and around the ovary there is a firm, yellow caseous substance, sometimes adhering to the surface of internal organs; the liver is slightly swollen, earth-yellow in color, fragile in texture, with densely packed pinpoint-sized grayish-yellow necrotic spots on the surface, and the gallbladder is enlarged, filled with green oily liquid; there are small hemorrhagic spots and superficial ulcers under the cornea; the epicardium has hemorrhagic spots, and pericardial effusion is obvious, pale yellow and transparent, mixed with fibrin.