I'm having a tough time introducing a yearling stallion to my present herd of 3 horses (2 mares/1 gelding). I kept the new youngster confined in an adjacent paddock for a week and monitored the "cross-fence" visiting between he and the others. There was the expected nipping, ear-pinning and squealing for a few days but it settled down to indifference by the 4th or 5th day. However, when I turned the yearling into a large pasture with the herd yesterday, my 9 yr old App mare and her 2 yr old filly chased the little guy until he ran into the pond! Thank God I was watching and went to his aid or I fear he would have drowned from exhaustion. I expected some biting, fussing and a little chasing, but not this!!!!!
After that, I put the new horse back in his original paddock but put the more settled gelding in with him. No serious problems, the older horse would posture a bit if the yearling got too close but nothing unusual. However, after what I saw from this older mare (I think the 2 yr old filly was just joining in because she saw her Mom doing it), I'm wondering if I'm going to be able to let them all into one pasture or not? A friend suggested putting the older mare into a round pen and working her for a bit, then add the yearling and work them aggressively together. His theory was that giving them a "common" problem to handle (me) would help them bond and take the mare's mind off chasing the new yearling.
I really need to get them all in the same pasture as soon as I can for grazing rotation purposes. And, it's crossed my mind that I might have to find the new horse another home but I'd rather exhaust every effort before I take that step.