The effects of ACTH,prednisolone and Escherichia coli endotoxin on some clinical haematological and blood biochemical parameters in dwarf goats

Summary

ACTH (μg kg ^‐1 i.v.) and prednisolone (1 μg^‐1 i.v.) caused a moderate but statistically significant inhibition of rumen contractions, whereas no effects on heart rate and body temperature were observed. Both hormones induced hyperglycaemia and leucocytosis, characterised by moderate lymphopenia and a profound increase in the number of circulating neutrophils. A significant decrease in plasma iron and increase in plasma zinc concentrations were observed.

After 3 daily i.m. injections of ACTH (10 μg ^‐1 day ^‐1) decreases were seen in both serum Alkaline phosphatase (ALP) activity and plasma trace metal concentrations; heart rate was significantly higher. Intraveneous injection of E. coli endotoxin (0.1 μg kg ^‐1) caused shivering, fever, inhibition of rumen contractions, changes in heart rate, lymphopenia, neutropenia followed by neutrophilic leucocytosis, hypoferraemia, hypozincaemia, hypoglycaemia and a decline in serum ALP activity. ACTH, given for 3 days, reduced the febrile responses to E. coli endotoxin, modified the changes in heart rate, intensified the inhibition of rumen contractions, and induced a more marked decrease in the number of circulating neutrophils. ACTH pretreatment did not affect the endotoxin‐induced decrease in blood glucose concentrations nor the drop in plasma zinc and iron values.

These results suggest that (1) glucocorticosteroids are not primarily involved in the fall in plasma iron and zinc concentrations during E. coli endotoxin‐induced fever, (2) the effects of endotoxin released glucocorticosteroids on white blood cells and blood glucose are masked by some other effect(s) of endotoxin, and (3) in dwarf goats, ACTH has antipyretic properties without influencing normal body temperature. This effect is probably not dependent on adrenal cortical activity.