Small intestinal carcinoma in sheep.

This communication reports a high prevalence of small intestinal carcinoma. Seventeen cases were detected during a survey of 6,248 sheep (0.272%) from 3 export abattoirs in southern New South Wales. The neoplasm appeared on the serosal surface of the jejenum and ileum as a ring of dense white fibrous tissue which caused stenosis and cranial dilation of the intestine. The mucosa and muscularis were thickened and folded but otherwise grossly normal except for 3 cases where small polyps were present. Metastatic lesions occurred regularly in mesenteric lymph nodes and sclerotic deposits were often present on the surface of abdominal visera. In one case metastatic nodules were found throughout the liver and lungs. Histologically, the glandular architecture of the mucosa and submucosa was disturbed and thickened with fibrous tissue. The muscularis was intact; however an intense desmoplastic reaction under the serosa contained scattered islands of PAS-positive epithelial cells; distinct acini were uncommon and mitotic figures rare.