Study on the thyroid function of thoroughbred horses by means of "in vitro" 125I-T3 modified and 125I-T4 tests

Abstract

Sera of 71 animals, divided in groups of males and females, in repose and after activity were studied. The method to establish the percentage of the 125I-lyothyronine retention resin (Test 125I-T3 or T3 ) was modified by the use of 0.2 ml of serum on the resin column, after addition of the marked hormone. This modification served to prove that thoroughbred equines show binding of the I -lyothyronine to the serum four times reduced, indicating, therefore, that these animals have four times more ligation sites of triidothyronin saturation in the serum, when compared with the results obtained from human beings. The variance analysis applied to the T3 Test showed no significant results at the 95% level as regards to activity. For the 71 animals, the author has found an average of 50.30% of the 125I-lyothyronine in resin retention, being the confidence interval for this group between 48.75% and 51.85% to a 95% confidence coefficient. Evaluating the results of the T4 Test by means of the variance analysis, we noticed that the male and female groups in repose differed statistically from the groups after activity to a 95% confidence coefficient. The author has grouped the results of the T4 Test of 32 equines, 18 males and 14 females, in repose, obtaining an average of 0.61 meg and 0.51 meg and 0.71 meg T4 /IOO ml as confidence interval to a 95% confidence coefficient. We have listed 39 results of T4 Test, being 23 males and 61 females, after activity, obtaining an average of 2.01 meg of thyroxin by 100 ml of serum and 1.72 meg and 2.30 T4/IOO ml as confidence interval to a 95% confidence coefficient.