The mare and foal should be in the corral, small paddock or large stall area you have been sequestering them in since birthing. Depending on the attitude of the mare, you can leave her loose or you may have to tie her up to keep her from interfering. A foal’s attitude is derived from the mare. How a mare reacts to things will transfer to the foal as it sees that this is the proper course of action. Irregardless of how you treat the mare, remember to be extra cautious and keep an eye on the mare. She can and will hurt you if she thinks you’re hurting the foal. DO NOT SEPARATE THE MARE AND FOAL.
To begin haltering a young foal, ensure you have a proper fitting halter. I like the kind that has adjustable the nose piece as well as the adjustable side or cheek pieces and crown piece. This type of halter allows further adjustment as the foal grows. You may have to adjust the halter to its smallest configuration in the beginning. It should fit as snugly as possible without being very tight. Some small amount of play is allowable, a too-large halter will allow the foal to slip it off or become entangled in it.
During the first week, you’ve made friends with the foal and are able to handle it all over its body. The foal has come to recognize you (and people generally) as non-aggressive and friendly. This allows you to get close to the foal and if you have a “helper” available, you can trap the foal with your arms without creating a panic. Once the foal is “trapped”, either you or your helper can slip the halter over the foal’s nose and close the crown piece. At this point, just stand back and allow the foal to explore the sensations of wearing the halter. At first, the foal will be confused and maybe a little frightened. It will shake its head, trying to dislodge the halter and maybe even bound around a bit. As the foal realizes the halter isn’t hurting it and is just an inanimate “thing” on its head, the foal may become angry at the halter. You’ll see an attitude change and at this point, the foal may try to scrape the halter off with a hind foot. Carefully watch to ensure the foal doesn’t catch a foot in the halter. This can lead to calamity.
Remember, the calmer and self assured you are, the calmer the foal will be. Allow the foal to wear the halter for about 15 minutes the first time, and then remove it. Allow the foal some time with the mare (about an hour or so), it will think about the experience and realize that nothing bad happened. Then repeat the haltering lesson. For the next several days, repeat the halter lesson in as quiet and calm a manner as possible. Repetition is the key, the more times you do it and let the foal discover that it’s a harmless lesson, the calmer and more accepting the foal will be. Eventually, you will be able to just walk up to the foal and place the halter on it.