I have a 12 year old gelding (that I've had for almost three years) and a 13 year old gelding (almost a year) who are best buds, never fought, got along with mares, have great ground manners and were always pleasures to have in my pastures. I recently took on a boarder who brought a mother and a four month old foal. My 13 year old will NOT leave them alone. He ran threw a stall guard (broke/splintered the wood) reared up and kicked out at me, his eyes are bulged out, breathes heavy whenever he is away from them, freaks out in his stall (paws, kicks out calls to others) this is totally not like him. I circle him in the paddok to calm him down. As soon as I let him go he runs over to the mama and baby and kicks my other gelding. This was the weird part, as my 12 year old was always top dog, although they NEVER fought until now, it was obvious. Any suggestions to help calm him down?
**PS The boarders just came about 5 days ago**