How much should your horse’s grazing muzzle restrict grass intake?

A horse grazing muzzle is a wearable hay net for your horse while on pasture grass. Just like hay nets for hay, the larger openings allow for bigger bites. Small-opening hay nets take much longer to consume; the same applies to grazing muzzles. The basket openings should be large enough to reduce frustration (if needed) and small enough to slow down eating and reduce overall intake. But how much does a muzzle restrict grass intake? It depends, so let’s start from the beginning.

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Basket-style grazing muzzles may help keep the sides away from your horse, reducing the chance of rubs.

Sugars, laminitis, and grazing muzzles

Any horse that is overweight or has a previous bout of laminitis or founder should wear a grazing muzzle on pasture and use hay nets for hay. For horses with metabolic disorders like pituitary pars intermedia dysfunction (PPID, formerly Cushing’s) and equine metabolic syndrome (EMS), the risk of laminitis and founder increases with pasture, too. Sometimes, these horses should avoid fresh grass and only use dry lots with hay nets and other slow feeders. Your vet can help you determine your horse’s overall risk of laminitis and how safe grazing is.

A high laminitis-risk horse has a compromised hormone chain that ultimately affects insulin. Insulin is directly related to blood vessel health in the hooves. When a horse eats sugars and starches rapidly, the hindgut microbes go into a feeding frenzy.

The resulting microbe “hangover” changes the pH of the hindgut, killing off some other microbes and creating endotoxins. These endotoxins then ride through the gut’s lining, bloodstream, and the hoof. And perhaps the vessels in the hoof are already compromised by insulin dysregulation, making these endotoxins more likely to harm the laminae.

One classic example is the clever pony unlocking and raiding the feed room and ending up with laminitis. Incidentally, many horses will get gas colic, too, as the microbe party also creates a lot of gas.

How muzzles help

The primary purpose of a grazing muzzle is to reduce the volume of grass your horse eats. This reduces calories and laminitis-inducing sugars and starches that make their way to your horse’s hindgut. As a bonus, muzzles also slow eating down, spreading out the sugars and starches, helping the hindgut avoid the overwhelming microbe feeding frenzy.

How much do grazing muzzles reduce grass intake REALLY?

Well, um, it depends on who you ask and the conditions in which researchers gathered estimates. For example, this article from the University of Minnesota Extension suggests muzzles reduce forage intake by an AVERAGE of 30%. Read about the study here.

And this study about overweight ponies and using grazing muzzles to restrict about 80% of grass intake. Read more about this here.

Incidentally, that study also revealed that unmuzzled ponies on limited turnout used that time to GORGE themselves. If your horse or pony is overweight, limited time on grass is NOT the answer. They will make up for it with vacuum-like feeding skills.

But what’s the real answer? Somewhere between a 30% and 80% reduction in grass intake? Probably – depending on a few things, mainly the muzzle design and the grass’s height.

Where to start with grazing muzzles

The ultimate goal of using a grazing muzzle is for your overweight or high laminitis-risk horse to enjoy the movement, herd companionship, and grazing that pastures provide.

First, your horse must learn that wearing a muzzle and grazing are joint activities – no exceptions.

Horses are keen observers of time on pasture and will quickly learn that a shortened turnout time means they must eat faster. If a horse knows that muzzle-wearing is only part-time, they will use the “naked” time to chow down as much grass as quickly as possible. This is the absolute worst thing for your horse’s hindgut!

The best time to train your horse to use a muzzle is anytime except the spring and fall when the grass is the most reckless with its sugar and starch content. Use a muzzle with ample openings, encouraging your horse to “figure it out.” Most horses catch on immediately.

If you start with tiny openings, horses can become frustrated and think of ways to remove their muzzle. Naughty horses!

As your horse becomes accustomed to wearing the muzzle, you can change the style or size of the openings.

This style has sections you can pop out, but not back in again.

The height of the grass matters, too.

Most muzzle brands work best when some bit of grass pokes through the holes for your horse to grab. Grass that is too long, even longer than six inches or so, will fold over when your horse places the muzzle down. Grass that’s too short barely pokes through, and most horses will scrape their teeth to get to the short pieces. Find that Goldilocks grass that is just the right height.

Read more about tooth wear and muzzles here.

When do horses need larger openings? Smaller openings?

Your horse’s needs dictate the best grazing muzzle design. Low laminitis-risk horses on low-sugar grass can have larger holes on their grazing muzzles.

Higher-risk horses and grass in peak growth season or stress need dry lots or smaller holes. Then there’s everything in between.

If your horse needs help maintaining a healthy weight to avoid some metabolic issues, you may be able to vary the size as the seasons change and your horse’s weight stabilizes.

Diet changes are another time to consider using muzzles. Equine nutritionists and vets suggest diet changes occur over two weeks to minimize gut disruption. The sudden bloom of spring grass is often so quick it equals a diet change. Or, a horse moving to a new barn or pasture may need a muzzle to acclimate to the change in food safely.

These inserts snap into the GG-Equine muzzles to change how much grass is available.

How to change the openings of your muzzle

Some grazing muzzles are rubbery, and you can cut the opening to allow more grass to come through. The downside is that it may be hard to make the space smaller again.

Other designs have slots that you can pop out, but once they are out, they stay out.

Some muzzles have removable inserts that alter the size of the openings. This allows for easy acclimatization to grass and adjustments based on your horse’s weight.

Does your horse have the right muzzle to restrict grass intake?

Help the overweight horses

An overweight horse should slowly, and I mean slowly, lose weight with a muzzle. Other horses that can easily become overweight can maintain a healthy weight using a muzzle.

Use a weight tape monthly (at least) to track your horse’s progress. Measuring your horse’s weight is fast and easy with this formula:

- (Girth in inches x Girth x Length) / 300 = Approximate weight in lbs.
- (Girth in centimeters x Girth x Length) / 11,900 = Approximate weight in kg.

The girth measurement is around your horse, just behind the elbows and the highest point of the wither. The length of your horse is the distance from the point of shoulder to the point of buttocks – and this may not be a horizontal line, which doesn’t matter.

This is not my pony; if it was, they would be wearing a muzzle.

For the horse with metabolic disorders

For metabolically compromised horses, their weight is also worth monitoring. EMS and insulin resistance (IR) go hand-in-hand with obesity in horses. Other metabolic disorders, like PPID may cause muscle and overall weight loss.

For any horse with metabolic issues, have your vet run regular bloodwork to monitor your horse. PPID horses often need medications, and bloodwork values of essential hormones can track the effectiveness of meds.

Horses with EMS can fluctuate in their sensitivity to sugars, which can also be monitored with bloodwork.

Pair your horse’s weight, bloodwork, and the sugary-ness of pasture to gauge the ideal restriction of grass intake. Your vet can certainly help you determine all of this.

For all horses, monitoring their weight and providing as much turnout as possible is the best for their overall health. Grazing muzzles can make that turnout safer, and longer!

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Grazing Muzzle by GG Equine

Basket-style grazing muzzle to help keep a horse at a healthy weight and help reduce the risks of colic and laminitis in some horses.

Use code 15PROEQUINE for savings sitewide on muzzles, halters, slow feeders, and more.