Experimental Infections of Lambs with Trichostrongylus axei; Investigations using Abomasal Cannulae

Abstract

Summary An investigation is described in which 2- to 6-month-old calves were infected with 150,000 to 300,000 Trichostrongylus axei third-stage larvae; one calf was challenged with 100,000 Ostertagia ostertagi third-stage larvae, and changes in constituents of the abomasal fluid were observed by the use of abomasal cannulae. Injection resulted in an increase in the abomasal fluid pH, pepsin and Na+ concentration, and a decrease in the concentrations of K+, Cl’ and dry matter. Changes in the pepsin concentration of the abomasal fluid were associated with similar changes in the serum pepsinogen. Saliva Na+ and K+ concentrations showed similar, but variable, alterations to Na and K values in the abomasal fluid. In lethal infections, the rise in abomasal pH was parallel with a decrease in the faecal dry matter percentage, and when the pH increased above 6 0 a terminal phase resulted where a marked weight loss occurred, serum albumin levels decreased and haemo-concentration occurred. The infection with O. ostertagi produced similar changes and differed only in the presence of a higher and sustained increase in serum pepsinogen.