Matt Zimmerman, of Caldwell, Idaho, is a colt starter, horse trainer, and nationally recognized mustang trainer. Zimmerman has competed in 20 Extreme Mustang Makeovers and has won or been in the top 10 every time. In 2019 he was the poster child for the Bureau of Land Management’s Extreme Mustang Makeover season, featured on the year’s calendar of Extreme Mustang Makeover events. Zimmerman’s well-organized facility contains indoor and outdoor arenas, roping pens, a unique assortment of challenging trail obstacles, and a collection of round pens.
“I use round pens to do a lot of the foundation groundwork with horses,” said Zimmerman. “Through round pen work I can get control of their feet and then their mind—and can keep things safe that way. The percentage of successes in establishing a solid foundation is very high with this approach.”
Zimmerman said he finds varying round pen sizes useful. “A 40-foot round pen is ideal for horses that are lazy or for where you are doing a lot of footwork,” he said. “Usually we start our horses in a round pen of this size. Too big of a pen and you are (expending energy and) just not going to see results. The larger sized round pens, 50, 60, or 70 feet, are generally used when riding. They give you more room, and it’s not too tight of a bend so that a horse can actually canter or lope.”
Zimmerman’s preferred style of riding round pen is one that protects the rider’s legs. “When I was a kid, we had a square pen built with railroad ties. When I was starting young horses, they often ran my knees into the railroad ties. With that in mind, for riding I prefer wood round pens with sides that tip out,” he said, adding that he builds this type of wooden pen with a slight angle to the sides. “Young horses tend to hug the fence, and when the wall tips out like this it will save the rider’s leg, making everything safer.”
To build in this type of slope, Zimmerman uses a level on every post, putting the bubble on the outside of one line.
Another option is a round pen with some type of solid wall. “Some metal panel pens have solid metal sheeting at the bottom of the panel,” he said. “This keeps dirt in the pen, and it protects the horse’s feet and legs from accidentally getting caught in the bottom part of the fence, which can be especially important when working with completely wild mustangs. You can even create this yourself with used conveyor belting and self-tapping screws.”
A solid or nearly solid fence also helps discourages horses from jumping out; the thought is if they cannot see what is on the other side, then they are less likely to try jumping. A disadvantage to solid-wall round pens is that in colder climates, “the south facing section of a solid wall round pen will stay frozen in the winter. And north facing sections can be slick,” Zimmerman said. Either of these points could render a round pen unusable in winter.
“Keep in mind, if you have a solid wall round pen and you think the horse is going to come at you, you need to have a way out of there,” Zimmerman cautioned. Mustangs tend to be more fear-based (than domestics), and some, in an attempt to defend themselves, can be aggressive. “You don’t want to have something that you can’t climb up quickly if you will be working with mustangs.”
A 6-foot-high (another requirement if you are considering adopting a mustang from a BLM facility), five-rail design discourages horses from jumping out, and most adult horse can’t reach their head through it.
