We have 3 adult horses, 2 geldings and a mare, they are living outside together in a field with a shelter. At the end of october we bought a foal and a filly, they are now 7 and 8 months old. We put them apart from the others, because one of the geldings is quite dominant and very protective of his herd.
So since 2 months they are neighbours, they see each other and smell each other en there is a lot of clacking teeth from the foals when they are near the big ones.
So yesterday I decided to put the youngsters with one of the geldings, the less dominant one, with the idea that is is good for their education to be with an adult horse. I saw the gelding playing a bit once or twice over the fence with the foal, all nice and friendly.
So I put them together, and the gelding looked at the foal for a second, then to the filly. Then he flattended his ears, lowered his head and attacked the filly. She was quite surprised, as I was, and ran to save herself. The gelding followed her, chasing her around the field, all the time with his ears flattened and his head low. And he kept going on, around the field, biting her in the hindlegs en her back, running at full speed. After 2 rounds, the filly tripped and fell on the ground en the gelding kept on going to attack her. This was near me, so I ran to chase de gelding, shouting loudly at him (I know I shouldn't, but I did. I admit also that my heart-rate was running very high as well). He backed up, the filly stood, and he recharged. So another round like that, now I had opened up a part of the fence hoping to separate the two. I managed to slow a little bit the gelding, but they all kept on running en the filly was stuck in a corner. Luckily she went half over half through the fence to the other side and the gelding didnt follow, so I had them separated. The foal that ran all this time after the two of them happened to go past the opening and I blocked the gelding and could close the fence before he could get to them again.
I was very lucky to find my filly with only a minor scratch on one leg, but otherwise unharmed.
So my question is, did anyone ever see this kind of behavior, is this normal? I have never seen this, when putting a new horse in a groupe I've seen some chasing, but never so aggressif, but I have never had foals before.
Thanks if someone can help and sorry for the lousy English :)