The effect of severe cystic hydatidosis on the liver of a Najdi sheep with special reference to the cyst histology and histochemistry.

A single case of severe hydatidosis in a liver of a Najdi sheep was studied. The estimated age of animal was 1.5 years and the liver was infected with 29 cysts and their diameters ranged from 4.0 mm to 5.1 cm. Cysts with diameter less than 10 mm were immature and those more than 1.5 cm were fertile and developed protroscoleces. Harvested protroscolices measured 120x60 to 140x80 um. Comparative histochemical studies by haematoxylin & eosin, periodic acid Schiff (PAS) and Mossaon's trichrome stains revealed that the cystic wall consisted of three layers which are germinal, laminated and fibrous respectively. The thickness varied with each stain. The glycogen and mucopolysaccharide content increased in infected sheep. Histopathological changes were the formation of fibrotic capsules around biliary tracts and portal vein and also leaky liver was marked in all the sections examined. Meanwhile, pre-malignant changes were seen in the different foci particularly around the biliary tracts and portal veins. The histochemical structure of the hydatid cyst wall may pave the way for effective therapeutic treatment.