Abstract: This experiment was conducted to confirm the sheep pox of the Small-tail Han ewes and explore the characteristics of the pathological changes. Based on clinical diagnosis, the six sheep suspected of sheep pox were diagnosed by the indirect ELISA for detecting antibodies and PCR detection technology. The pathological changes were observed by microscopy, light microscope, and transmission electron microscope. The indirect ELISA showed that all the samples of 6 sick sheep were antibodies positive for Capripox. The PCR results showed that the special 585 bp target gene fragment of sheep pox virus (SPV) was amplified and the SPV was diagnosed as the pathogen of the sick sheep. The pathological changes of clinic and autopsy showed that the skins of sick sheep had hyperemia, papules, erythema, and necrosis in glabrous areas, and the suppuration and ulcer of the tails root were often observed. There were a large number of papules, pox lesions, necrosis, and ulcerations on the mucosa of the digestive tract, especially the mucosa of the tongue and rumen. At the same time, there were pox lesions and necrosis in the lungs, livers and spleen. The histopathological changes indicated that the exudation-proliferation nodules and necrosis-proliferation nodules were mainly changes of pox lesions in the lung, and there were a large number of sheep pox cells around the blood vessels and bronchioles, and the eosinophilic inclusions were often present in the cytoplasm of sheep pox cells. In the diseased mucosa of the digestive tract, the epithelial cells were varying degrees of proliferation and vacuolar degeneration, the lamina propria and submucosa were varying degrees of congestion and edema, and there were also many sheep pox cells and their eosinophilic cytoplasmic inclusions. There were also necrosis-proliferation nodules in livers, spleens and kidneys. The ultrastructural changes of lungs showed that the alveolar epithelial cells were swelling, nuclear concentration, chromatin aggregation, mitochondrial swelling, fractured cristae and cavitation, and there were cytoplasmic inclusions. Those results confirmed that the important pathological changes of the mucosa of the digestive tract and lung are also one of the representative changes in sheep pox. In particular, there were a large number of sheep pox cells in pox lesions, it has important pathological diagnostic significance.

Key words: Small-tail Han ewes, sheep pox, ELISA, PCR, pathological change