THYROXINE SECRETION RATE IN THE HORSE IN VARIOUS PHYSIOLOGICAL STATES

Publisher Website
Google Scholar
Abstract
SUMMARY: Studies on the rate of thyroxine secretion (t.s.r.) in the horse, as measured from degradation of labelled thyroxine, are reported. In the resting horse, the mean t.s.r. was 0·49 mg./453·6 kg. (1000 lb.), with a mean value of PBI of 1·80 μ./100 ml., volume distribution of 60 1., and a half-life of 2·31 days. Partly and fully trained horses showed increases of 38% and 65% in t.s.r. associated with lower values for PBI and a greatly decreased half-life. During adaptation to cold, there was an increase of 66% in t.s.r. In horses adapted to cold, t.s.r. was increased by 17%. In pregnancy, the mean increase in t.s.r. of 18% was not statistically significant.