A Guide to Grazing Muzzles

Over the years, I’ve owned multiple horses that required a grazing muzzle, including my current two. I consider myself a bit of a grazing muzzle aficionado, but as with any management tool, it’s important to stay current on updates and recommendations.

What Makes a Horse a Candidate for a Grazing Muzzle?

According to Krishona Martinson, Ph.D., Equine Extension Specialist for University of Minnesota Extension, horses that are clinically healthy yet overweight are the best candidates for a grazing muzzle, as opposed to those with a history of laminitis or a diagnosis such as equine metabolic syndrome or Cushing’s disease.

“[The best candidates are horses that] can graze without the negative health complications, but we don’t want them to gain excessive amounts of weight, or we would like them to lose some weight,” she says.

In these situations, using a grazing muzzle can help horse owners manage their easy keepers with their herd, while still allowing them to exercise and continue to be herd animals.

Rhonda Hoffman, Ph.D., Professor and Director of Horse Science at Middle Tennessee State University, further elaborates that horses with a body condition score of 7, 8, or 9 (on the 1-9 Henneke Body Condition Scoring system) as those that would benefit most from the use of a grazing muzzle to lose weight and decrease the risk of developing insulin dysregulation.

While other types of horses can benefit from a grazing muzzle, such as those who have been diagnosed with equine metabolic syndrome or those who have had laminitis, both experts agree this is not always an ideal management practice.

“These horses require a diet low in nonstructural carbohydrates,” says Martinson. “Our predominately cool-season grasses in most parts of the U.S. are not a great forage source for these horses. A grazing muzzle will slow their consumption and reduce how much they can take in, but it does not remove the nonstructural carbohydrates. I think that is an important distinction.”

Hoffman advises that even if they haven’t been formally diagnosed, horses with a cresty neck could have insulin dysregulation or metabolic issues, as can horses who have previously foundered, even if their current body condition score is good. She recommends that you consult with your veterinarian to determine if limited grazing using a muzzle is OK, or if these horses should be completely restricted from pasture.

When to Use a Grazing Muzzle

As useful a tool as grazing muzzles are to help your horse maintain a healthy weight or lose weight, he does not need to wear a grazing muzzle year-round.

“It depends on location and rainfall,” says Hoffman. She explains that grass has little nutritional value during times of drought and in freezing temperatures. Wearing a grazing muzzle during these times is not going to make a discernible difference, she says.

Similarly, Martinson advises their use during the growing season.

“Depending upon your location in the U.S., your growing season is going to be different,” she says. She elaborates that for approximately two-thirds of the U.S., the growing season is from mid-May to mid-October. It is during these months that she advises their use for horses that are clinically healthy but need to maintain or lose weight.

Introductory Period

“When we have done research using grazing muzzles, or anything that restricts or slows down foraging [even a hay net], it takes horses time to acclimate and learn how to use the barrier put in front of them,” says Martinson. “My recommendation while they are out on pasture is to put the grazing muzzle on and watch them carefully.”

To make sure that your horse is consuming enough calories, especially during the first two to three days of use, Martinson advises placing the horse in a stall or dry lot overnight and feeding a small amount of hay to keep his digestive system moving. Also check that the grazing muzzle fits into your horse’s water source.

“But in my experience, and in our research, every single horse that we fitted with a grazing muzzle has figured out how to graze with it on fairly quickly,” she says.

The Proper Fit of a Grazing Muzzle

Ensuring a proper fit for your horse’s grazing muzzle can be a very individualized experience, and it plays a critical role in the grazing muzzle’s use. But with a variety of styles to choose from and a little ingenuity, it is possible to maintain your horse’s comfort.

All styles of grazing muzzles form a basket designed to fit over the horse’s muzzle, and the materials from which they are constructed range from a poly/nylon mix to both firm and flexible plastic.

The method of attachment differs depending upon the style of muzzle you choose, with options that include a continuous, single-piece style; a four-point leather attachment; and Velcro or plastic ties that can be attached to a standard or custom halter.

Within these styles, you are likely to find one that your horse is both likely to keep on and that will also stand up to his particular methods of wear and tear, while minimizing or even eliminating rubbing.

But even if the grazing muzzle you choose checks most of your boxes, there may still be areas of friction. Experimenting with different materials such as fleece, duct tape, Vetrap, slinky-material fly masks worn underneath the halter, and more can help minimize rubbing at pressure points.

No matter which style you choose, both experts agree that safety should be at the core of choosing and fitting a grazing muzzle. Any product, whether it is the method used to affix the muzzle to the halter or the halter itself, should be designed to break away if the horse becomes entangled.

Beyond that, choosing a muzzle that is not so loose-fitting that it encourages excessive rubbing can help cut down on any potential issues your horse may experience.

No matter how daunting your choice of grazing muzzles may seem, the good news, according to Martinson, is that any grazing muzzle you choose will reduce forage intake by approximately 30 percent, with some of the more restrictive designs reducing intake still more.

Almost any grazing muzzle is a good choice if it meets the above criteria for safety and fit.

Regular Inspections

Once you have made your selection, both Hoffman and Martinson recommend continuous evaluation of your grazing muzzle.

“Every single time your horse goes out or comes in, pay attention to [not only fit] but also wear on the grazing muzzle itself,” says Hoffman.

She advises paying particular attention to whether the grazing muzzle was damaged during turnout and for areas of excessive wear that may be developing over time.

Tip: As a longtime user of grazing muzzles, one pro tip that I highly recommend is tying one or two pieces of colorful surveyor’s tape to your grazing muzzle. Doing so can save countless hours looking for your grazing muzzle if it comes off in the pasture. 

A Daily Break

The method in which you use a grazing muzzle is another important aspect. According to Martinson, research out of North Carolina done by Paul Siciliano, Ph.D., shows that when horses are restricted from pasture—for example, if they are only turned out for two hours or if a grazing muzzle is applied for two hours and then removed—horses will learn that schedule.

So in those two hours they are allowed to graze, horses will consume calories significantly faster than normal grazing speed. Siciliano’s research indicates that in as little as three hours of grazing, horses can consume up to two-thirds of their calories for the day.

This research has led to various recommendations about how grazing muzzles should be used. In a perfect world, each day your horse would be allowed an extended break from wearing the grazing muzzle. For example, to further encourage maintenance of weight or weight loss, the horse could be brought into the barn or placed on a dry lot at night, during which time he would be fed lower-quality (more mature/lower calorie) hay.

“Any time you leave a horse out 24/7, even with a halter on, it is going to create rubs,” says Hoffman. “With a grazing muzzle, they are pushing their nose against the bottom to force grass through the holes. A break helps to avoid skin conditions and rubs.”

Allowing for a daily break from wearing a grazing muzzle can also help to preserve the muzzle’s longevity. During the hot summer months, Hoffman says removing the muzzles for a period keeps the horse cooler.

But allowing for a break while at the same time keeping the horse off pasture is not always possible. In those cases, it’s best to increase your monitoring of the horse to ensure continued proper fit and watch for rubs and wear patterns.

Weight Loss Outcomes

Just one benefit of using grazing muzzles is that they can allow for a slow, safe weight reduction.

“If you reduce calories by about a third, your horse should be able to lose one body condition score [number] per month,” says Martinson. “This is considered a safe amount.”

She further explains that the body condition score amount is going to vary depending on whether you have a draft horse, a light horse, a pony, or a Miniature Horse.

“It could be as little as 10 pounds or as much as 50 pounds, depending on the size of the horse,” says Martinson.

She cautions that adding feed and treats to your horse’s diet can be counterproductive to achieving your loss goals, while exercise, when possible, can enhance your efforts.

Grass Height and Type

You may have read conflicting reports about appropriate pasture grass height and types, perhaps finding that your pasture situation is not ideal for a horse wearing a grazing muzzle. However, Martinson’s research has led to some interesting discoveries.

“We would like to see our cool-season grass pastures between 3 and 8 inches in height,” she says. “Never lower than 3 inches.”

Regardless of whether your horse wears a grazing muzzle, this practice prevents overgrazing. Further, she says, horses prefer different types of grasses. Some of these different grasses grow straight up, while others grow along the ground.

It used to be thought that a grass that grows straight up would be more accessible by horses wearing a grazing muzzle. Instead, she says, research found that how the grass grows made no difference to the horses, and their ability to successfully graze through the muzzle remained unchanged, regardless of grass type.

Stress Levels

Martinson says that a common misconception about grazing muzzles is that they cause an increase in the stress levels of the horses wearing them. However, she says that in recent years, research conducted by Amy Burk, Ph.D., at the University of Maryland measured levels of the stress hormone cortisol, comparing levels in horses wearing a grazing muzzle and those without.

Not only were the stress levels similar, but the herd hierarchy remained unchanged. The only change noted was a reduction in bite marks and a reduced ability for horses to groom themselves or others.

Key Takeaway

While there is a lot of information to take in, with these researched-based recommendations in mind, you too can make the best choices for your horse in all aspects of grazing muzzle use.

This article about grazing muzzles appeared in the April 2024 issue of Horse Illustrated magazine. Click here to subscribe!