First I worked him in the roundpen and let him get a little exercise before we start. He was looking around, watching other horses, and being a bit absentmined. I roundpenned him for a few minutes until he started listening to me and claming down.

When sacking a horse out, it is a good idea to have a halter and lead on and keep the horse untied. In case of a horse panicking (which may happen at first), you want to make sure the horse will not be injured.You also want them to realize they can move away if they are afraid. They may, at first, jump back. Knowing they have freedom to move takes away some anxiety. If your horse is only tolerating an object because he is tied and can't flee, then he is only learning that he can't get away, and not that he shouldn't be afraid. The goal of sacking out is to teach a horse not to fear.

Then I brought the saddle pad over and let him sniff it. You want to let the horse see the object so they aren't suddenly spooked. Don't just pull it out and start flinging it around, let them have a second to see what is going on. Then you can begin to swing it around. The horse may step back; That's OK. You want him to get comfortable with the object moving all over, all around his body. He should begin to get used to it after a little while. In the second photo, Blaze stepped sideways when I began to swing it.

Here I actually flung it onto his back (after he is used to it being swung in the air around him). He stepped a bit but then stood still.

He began to tolerate me swinging, flapping, and rubbing the blanket all over his body. He no longer saw it as a 'scary' object.

After awhile, he is used to it all over his body-- his rear, legs, belly, and even head.

I let him see it laying on the ground; I don't want him to be afraid of things around his feet. And then he decided he'd sack me out!

I strongly recommend that all horses be sacked out with a rope. Before ever riding a horse I make sure that it is used to ropes all over its body-- around the ears, over the face and neck, under the belly and legs and tail, etc.
Why? Because a horse that panics when a rope gets between its legs is a potential danger to itself and riders. I have seen horses nearly break their neck because, when standing tied, they got the rope over their neck.
In case of an accident (tack breaking or slipping, or a horse getting loose with tack dangling, for example) you want a horse that will stand calmly and not freak out. It could save your life. I have seen saddles slip beneath a horse, causing a potentially dangerous situation. If a horse panics when tack is tangled, it may injure its rider, handler, or itself. The last thing you want is a terrified horse if your tack breaks or gets tangled up.

I use a soft cotton leadrope and swing it gently. If you have a long leadrope, you can use that, or you can use a different rope. You don't want to hit the horse. At first your horse might think you are cueing him to run off, so he might start moving away. Gently stop him and start again. Just like with a saddle pad, the idea is to slowly get him used to the rope so he won't fear it. Throw the rope at the ground, under his legs, over his body, under his belly, between his legs, etc. Be careful (as always) because some horses freak out when they feel a rope under their belly or around their legs.

When he was comfortable with the rope, I moved on to a very scary object: a plastic bag tied to the end of a buggy whip. Again, I let him have a look at it, but when it rattled he took off!

He danced arouned quite a bit before he'd let me shake it and not move.

I didn't try to bring it close to his body until he was comfortable with it being rattled around in the air, up and down, and sideways.

After awhile he was comfortable enough to let the bag touch him-- and even let it go under his belly and on his back...

... and wear it on his head.

 

Remember to be safe, and don't move to fast. A scared horse is a dangerous one! Don't get frustrated or upset. You want your horse to get comfortable and be fearless; if you are impatient, it will only make them worse. Try to end on a good note, and be sure to give them a lot of attention and tell them what a good job they did!