Evaluation of serum pepsinogen as a diagnostic marker for parasitism in farmed red deer.

Abstract

Aim: This study presents data of pepsinogen analyses from samples collected during a prior investigation of the species of internal parasites, production effects and diagnostic markers for internal parasitism in farmed deer in New Zealand. Methods: Two groups (n=20) of weaned red deer were naturally infected with Dictyocaulus spp. and mixed GI nematodes. The first group (suppressive treated control), was treated every four weeks with anthelmintic. The second group (trigger treated) received only treatment when trigger criteria were met. Individual body weight, faecal egg and larvae counts were measured every two weeks and every four weeks the animals were sampled for serum which was stored frozen. Results: Serum pepsinogen concentration were measured but were low, with levels not reaching above 225 mU. No difference in pepsinogen mean concentration was seen between the two groups on each sample date. Faecal egg and larvae counts ranged from 0-500 epg and 0-120 lpg in the trigger treated group and few animals in the suppressive treated group were egg or larvae count positive. No correlation was found between mean egg or larvae count and mean serum pepsinogen at any sampling day in either group. A significant inverse correlation was observed between liveweight gain from January to December and mean log pepsinogen for each animal in the trigger treated group. (r = -0.5177, p<0.001). There was a positive correlation between mean log pepsinogen and liveweight gain for the suppressive treated group (r = 0.2192, p=0.019), but there was no significant correlation between mean log pepsinogen and sampling date, suggesting this was not a seasonal efffect. There was no difference between groups in the proportion of animals positive for pepsinogen at any sampling date. Conclusion: Serum pepsinogen concentrations could not be used as a marker of internal parasitism in deer with the apparently low worm burdens and faecal egg and larval counts observed in this study. Further research is necessary in deer with greater worm burdens and faecal egg and larvae counts to evaluate the diagnostic potential of this marker at higher pepsinogen concentrations. Clinical relevance: Data suggests that in animals with low faecal egg and larvae counts, liveweight gain is a better indicator for subclinical parasite infection then serum pepsinogen.