AND PERSONALITY 



If the relative weights are taken into consideration, it 

 will be noted that the brains of the thoroughbreds Pennant, 

 Equipoise, and the Equipoise colt are all larger than the 

 brain of Nureddin, the Arabian. 



It will be noted in the Arabian horse Nureddin that 

 the thyroid gland is larger than the adrenal glands, showing 

 the adaptation of the Arabian for long-distance traveling. 

 In the colt of Equipoise, also, the thyroid gland was larger 

 than the adrenal glands, showing that the energy organs 

 had not yet assumed the adult pattern characteristic of the 

 thoroughbred. In Equipoise the thyroid-adrenal relation 

 is the pattern of the thoroughbred horse. In a study of 142 

 thoroughbreds, this is the pattern that obtained. 



Pennant, a retired thoroughbred, twenty-seven years old, 

 showed pathologic changes in the heart and thyroid gland; 

 so these organs could not be used for comparison. 



Of significance is the fact that of a total of eighty-seven 

 fetuses and newborn foals of thoroughbreds examined by 

 us, eighty-three followed the Arabian pattern in which the 

 thyroid gland is larger than the adrenal glands. In one grade 

 foal and in twenty saddle-bred and in two standard-bred 

 foals, a similar thyroid-gland dominance was found. It 

 would appear that the energy organs in the prenatal 

 state have the pattern of the Arabian ancestors of the 

 thoroughbred. 



The thoroughbred, or race horse, is under the control of 

 man a control that allows the brain, the heart, the thyroid 



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