Pepsinogen types in worm-free sheep and in sheep infected with Ostertagia circumcincta and Haemonchus contortus.

Pepsinogen isolated from the plasma of Dorset wethers with abomasal burdens of Ostertagia circumcincta was found to have the same proportions of three zymogen subtypes as that isolated from the plasma of Merino wethers with abomasal burdens of Haemonchus contortus. It appears that the underlying pathophysiological response which causes increased plasma pepsinogen concentrations during abomasal parasitism may be the same irrespective of the breed of sheep or species of parasite.