Ok let me preface this with this is NOT the article I read as the one I read was a scientific study/scholarly article. The original was in French. BUT this is along those same lines and maybe she has read the same. My eyes can't take the digging any longer. I did also find parts of articles by an MF Bouissou that suggest she could be the one that wrote what I read. My subscriptions to those sites expired so I don't have access to those complete writings.
Katherine A. Houpt, VMD, PhD, DACVB
Mar 25, 2019QUESTION: My gelding is the leader of our herd, and he takes his job seriously. He is always on the lookout, he always wants to be with his girls, and he gets anxious when separated. Since he always wants to know where his ladies are, they are a big distraction. Iíve dealt with barn- and buddy-sour horses before, but this guy is so full of energy and spirit Iím just not sure anything is working. I am open to more suggestions or just reassurance itís a long slow road Iím riding.
Pittsboro, North Carolina
Anwer: Your horse is not unusual. Many geldings display this type of behavior. I would not describe it as dominance but rather as male sexual behavior. He may also be dominant---that is, demanding first access to resources such as food, salt licks or the run-in. Most males are dominant to mares. But the real problem is that he has assumed the role of a stallion in his group.
When a horse is castrated, his testicles---the source of the hormone testosterone---are removed. Unfortunately, one of the greatest effects of testosterone occurs long before the colt is castrated, while he is in utero. During pregnancy, the mareís hormones stimulate the fetusís gonads so his testes pump out a lot of male hormones called androgens. These androgens act on the brain to masculinize it. The maleís brain is different from that of a female; it has a much larger sexually dimorphic nucleus. As a result, many geldings still behave like stallions even after their supply of testosterone abates.