DD picked up her 6 year old OTTB off the track on Thursday and had him at my place on Friday (all of this 11 years ago). As I recall, we put him in the 100 x 132 “pony pen” and let him hang out with the other horses who were on the other side of the fence for a week or so. This acclimated him to grass and his new friends (all geldings). After a week, we put him out in the 2 acre pasture with one buddy and watched them. All quiet all good. Eventually he was turned out with three more geldings and they formed a peaceful herd of 4 --all out 24/7 with big run-in sheds.
I do recall two things. When the other horse walked up the hill away from the OTTB the first time (we have rather steep grass covered hills in our pastures), the OTTB paused for some time at the bottom of the hill. My feeling was he’d never seen unlevel ground and wasn’t sure how to navigate going up hill. Eventually he figured it out though and became a solid 3-day horse.
The second recollection was rain. I was working in the barn and it began to rain --that summer rain that is cold an heavy. All the other geldings ignored the rain and continued eating grass. The OTTB raced to the gate and began to paw and sway. Clearly, being out in the rain was not something he thought was appropriate for a horse of his status!
He is blanketed, even now at almost 20 --he never grew the coat the others did. And we eventually pulled shoes. The farrier predicted dire consequence, but while not a great hoof, he does keep a good enough foot to walk on the pasture with comfort.
He developed bone chips and after a fine career as a 3-Day horse is a pasture ornament here at my place along with another great horse. He’s pleasant.