Gross pathology and histopathology of haemonchosis in sheep and goats in Iraq.

The response of Awassi sheep and a local breed of goats to H. contortus, the prevalent ovine and caprine strongyloid species in Iraq, was studied. A dose of 500 H. contortus (sheep origin) larvae kg-1 body wt. induced clinical and pathological changes of haemonchosis. Although the percentage recovery of worms was higher in sheep, the pathological (gross and microscopic) changes were more marked in infected goats. The extensive abomasal changes noted in goats were, in general, accompanied by a higher density or larvae in the gastric wall; the pathology did not necessarily depend upon parasite count alone and a definite relationship could not be established. The tissue changes in the goats are possibly of immunological origin, although a genetic resistance may operate, primarily at the level of worm establishment.