Your Foals Play Pen
Your Foal's "Play Pen"
While your mare may not even dream of going near a barbed wire fence, you can be sure that your foal, like any toddler, will test all the boundaries. Since barbed wire is very unforgiving and not recommended for any horse, this would of course be a really bad choice for a tender young baby. The following are much safer options:
Smooth Wire Fencing can be a good option since there are no barbs to cut or scratch, but since it it similar to clothes line, it will stretch and need to be tightened from time to time. Now and then, a really precocious foal will decide to shimmy under it (just like a dog does), and end up on the opposite side, trying to find its way back to mama.
Metal Pipe Fencing is popular with many breeders. It is very solid and has little give, but because it is highly visible, most horses do not run into it. While expensive, there is little or no regular maintenance required.
Board Fencing is attractive and relatively inexpensive, but requires maintenance to keep it looking good and to insure that your horses are contained. Then too, boards will break if your horses become spooked and heedlessly run through the fencing. Also, fencing nails can become a hoof hazard if they come loose and fall to the ground.
PVC Fencing, while very attractive, is not without its issues. It comes in a variety of styles and color, and is pretty much maintenance free, but can "pop" out of place easily if leaned upon by your horses. Then too, the initial cost of the fencing can be prohibitive.
Mesh Fencing can be a relatively inexpensive and safe enclosure, if you are careful to make sure the size of the mesh openings are small enough so that hooves cannot be pushed through at any point. Flagging tape or a top rail of wood is advisable since wire mesh is not very visible.
Whatever your choice, be sure to inspect your fencing for safety issues from time to time and thus avoid any problems before they happen.