Parasites as stressors: plasma cortisol responses of goats infected with the stomach worm Haemonchus contortus to exogenous corticotropin (ACTH).
Ten male, juvenile pigmy goats of similar age and weight were allocated randomly to two groups. Goats in one group were each inoculated with 20,000 infective larvae of Haemonchus contortus. The other group served as uninfected controls. Goats were housed together, and precautions were taken to avoid the creation of differential, between group, stressogenic circumstances. Body weights, nematode egg production, hematocrits, and clinical signs were monitored over a 61-day period following inoculation of larvae. On Days 59 and 61, adrenal response tests (ART) were conducted by measuring the levels of plasma cortisol before and 2 h after administration of porcine ACTH at the rate of 0.35 I.U. kg-1 body weight on Day 59 and 2.2 I.U. kg-1 on Day 61. Although the infections did not reduce body weights, they were 'heavy' on the basis of egg production, and led to significant reductions in packed erythrocyte volumes. There was no significant difference between the groups of goats in the responses to ART, indicating that the infections did not produce sufficient stress to reduce the ability of the adrenal cortex to respond to exogenous ACTH.
D000324:Adrenocorticotropic Hormone; D000818:Animals; D006041:Goats / Q000469:parasitology*; D006188:Haemonchiasis / Q000097:blood / Q000150:complications / Q000662:veterinary*; D006400:Hematocrit / Q000662:veterinary; D006854:Hydrocortisone / Q000096:biosynthesis / Q000097:blood*; D008297:Male; D011897:Random Allocation; D013312:Stress, Physiological / Q000209:etiology / Q000662:veterinary*; D014252:Trichostrongyloidiasis / Q000662:veterinary*
D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone