The present report describes a comparative study in dwarf goats on human IFN-alpha 2a (0.5 x 10(6) IU kg-1 body weight IM), poly I: poly C (an interferon inducer; 30 micrograms kg-1 b.w. IV), and Escherichia coli endotoxin (an I1-1 inducer; 0.1 micrograms kg-1 b.w. IV). Although IFNs are considered to be species specific, human IFN-alpha 2a was very potent in dwarf goats. All 3 stimuli induced the 'acute phase response'. Among the varied physiological alterations, which together produce this response, are fever and depression, inhibition of gastric function, tachycardia, a decrease in serum alkaline phosphatase activity, leukopenia, lymphopenia and neutropenia followed by neutrophilic leukocytosis, hypoferraemia and hypozincaemia. The results suggest that, apart from I1-1, IFN-alpha also seems to mediate the systemic 'acute phase response' to certain exogenous stimuli.