Diagnostic Research Of Yak Pneumonia

Abstract : To find out the death reason of the yaks in Qinglongsi village, Nanxing town, Feng city, Shaanxi Province, pathologic observation and bacterial diagnosis are performed for dead yaks. ⑴The nervous system: Microscopically ①Cerebral cortex nerve undergoes degeneration and necrosis in variable levels; ②nerve cell enlarge, and nervephilic phenomenon and satellite phenomenon appear; ③cerebral capillary shows as hyperemia, and perivascular space obviously enlarge; ④micro-thrombus, which is found formed by agglutinative and lytic erythrocytes, can be seen. Grossly a few small haemorrhagic focuses appear in cerebral cortex.. ⑵The cardiovascular system: Microscopically ①myocardial cells undergo granular degeneration; ②collagenous fibers swelling and hyline degeneration occur in connective tissue of endocardium and epicardium in a few cases. ③there exists infiltration of neutrophic granulocytes and lmphocytes among myocardiacfibers. Grossly ①pericardial cavity accumulates yellowish dropsy. Hamorrhageic spots and ecchymoses are scattered with endorcadium and epicardium,especially with coronary groove, vertical groove and vertricle epicardium. ⑶The respiratory system: the inflammatory focuses are scattered with pulmonary lobes in variable levels. Bronchiole wall and Capillary of alveolar wall encounter hyperemia .Lymphoidocyte, lymphocyte and neutrophic granulocyte infiltrate around hyperemia zone. The lumen accumulates abundant erythrocyte and leukocyte. Hamorrhrage and serofiuid exudation or inflammatory cell (such as neutrophilic granulocyte and macrophage) occur in some alveoli. ⑷The digestive system: hepatocyte undergoes granular degeneration and partly develops into fatty degeneration. Local hepatocyte shows necrosis. the number of eruthrocyte and stellate cell increase in hepatic sinusoid, where inflammatory cell (such as neurophilic granulocyte and lymphocyte) exudates in some cases. Rumen shows tympany. Not foreign matter is observed in lumen or others. Mucous membrane of rumen and omasum is prone to shed. There is small hemorrhagic spot under mucous membrane. This phenomenon is found in mucous membrane of abomasums. There remains soft chyme in in intestines, where its cavity is filled with air. Intestine is markedly lighter in color.Submucosal layer ,in which macrophage and lymphoidocyte infiltrate, is loose and edematous. Epithelium of renal tubule undergoes granular degeneration . Necrotic epithelium sheds into renal tubule. There exists small hamorragic focus in renal mesenchyme. Mesenchymal capillary shows as hyperemia. ⑸The lymphatic system: spleen are dark in color and doesn't enlarge. There are small hemorrhagic spot under the splenic coat. (6)Bacterial diagnosis:two pathogenic bacteria, namely, Pasteuria and Staphylococcus, are isolated from object yak. This case may be caused by pathogenic Pasteuria, although artificial infectious model is bound to support it.