If you have two horses, especially if you acquire one after having your horse living with you for several years, you’ll be tempted to move the second one in with the first one, and feed them together.  But first, take pictures of each horse, and date them.  Take more photos the next month, and the month after that.  If neither one has gotten fat, congratulations.  That’s one less problem to worry about.  But if one gets fat and one day you notice you can see the other’s ribs, you’ll have to separate them because the fat one is hogging all the food.

Prim is the dominant horse—she pins her ears and refuses to let Gunner anywhere near her food.   In fact she will occasionally drive him away from his food.  But Prim is the one who got skinny.  Why?

In the wild, horses forage.  They move throughout their territory and stop to graze, move on, graze somewhere else, and then head for water.  The old boss mare usually choreographs their movements.  (The stud is watching for other stallions who might want to fight him for his herd of mares, plus immature horses of either sex.)

If you rescue a horse who’s been systematically starved—Gunner’s owners didn’t live on the property, and drove up to feed him once a week—you have an obsessive eater.  Gunner does not behave like a normal horse, and by that I mean one who lives in the wild.  Once he sticks his muzzle in the feeder, he doesn’t take it out again until every last stalk of hay is gone.  (As far as he’s concerned, no hay is “too stemmy” to eat.)  When they lived together, any time Prim left off eating to gaze dreamily off into the horizon, thinking horse thoughts, Gunner would move on to her feeder.  When she felt like eating again, there was nothing left.  But it might take you a while to notice it unless you take photos once a month, and compare them.

And that is why Prim and Gunner now live side by side in a divided corral.