These little flags, which flutter in the breeze, are often employed by those who have wire or electric fence, to call attention to the location of the top wire, and they can be very effective. Where you place your fence also has a lot to do with how visible it will be to your animals. Horses are far-sighted creatures who tend to look to the horizon. For maximum visibility, install your fence at a height at least equal to the height of your tallest horse's eyes, when he holds his head up. Most fence installers recommend a fence at least six feet high for stallions.
Social pressures are usually to blame when horses challenge fences.
Virtually any horse can clear a five-foot fence from a standstill if he's sufficiently motivated, but very few will be keen to clear two which are only eight to twelve feet apart. This also virtually eliminates squabbling, or courting, over the fenceline. Rounding the corners in all of your paddocks will allow a horse being chased by a more aggressive pasturemate to find an escape route, rather than being cornered and thoroughly thumped on. Place your gates so that horses don't get cornered and crowded when you're leading animals in or out, and fence off swampy areas, trees, and power line guy wires, or anything in which a horse could become mired, entangled, or impaled. That way, when horses lean on your fence, the boards, pipes, or wire will be pushed against the posts rather than off them.