Looking for anyone with experience with a gelding being aggressive. I've owned him over 3 years. When I bought him he was separate from the rest of my horses for a couple months, then I turned him out with 1 gelding and 3 mares. He was low man and got along with everyone fine. We sold my husbands gelding about 1 year ago, then bought a 3 yr old gelding 6 months ago. My gelding tried to basically kill him!  So we just kept the new gelding in a pasture by himself and left the others together.  We put a mare up front with the new gelding for a couple weeks. Last night I went to put the mare back in the pen with my gelding and 2 mares and my gelding tried killing her??  Not sure what is going on? They were friends 3 weeks ago. Any advice? He hasn't been hauled any where in over a month. We are on winter break. 

Talk to your vet about a Depo shot, that should help.

What a Jerk,

I'm guessing he thinks he's got a little band of mares and they are his territory and the mare coming back is tainted (love) now.

Kinda of what I was thinking. I'm going to put him in the other pasture by himself. He can deal with his feelings then.

What is a depo shot? IT is the gelding with these issues not my mares.

We have given aggressive geldings regumate too with good luck

It's also prescribed for aggressive geldings and stallions.  Again, talk to your vet about it.  If nothing else google can geldings get hormonal, then talk to your vet.