Grazing Muzzles and the Effects on Herd Behavior


Aside from the generic and incorrect “muzzles are cruel” statement about grazing muzzles, you may also hear that muzzles “it’s stressful, and muzzles don’t allow for normal herd interactions.” Let’s look at this through the lens of science. 

Hint – it’s false! 


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The Study


  • Two researchers at the University of Maryland, Amy Burk, Ph.D., and her graduate student, Kristina Davis, set out to observe the behaviors of horses while wearing muzzles. The findings were presented in 2019 at the Equine Science Society Symposium. 


  • Mini horses were the test subject and were divided into three groups for observation over three weeks. One group was totally naked – no muzzles! Another group wore a muzzle for 10 hours a day, and the third group wore a muzzle for 24 hours a day. 


  • Behaviors were noted: body scores, weights, cortisol levels (to measure stress), heart rates, and other physical measurements. After this initial part of the experiment, the continuously muzzled horses lost weight and did not show signs of frustration or stress. This group also grazed more, rested less, and had lower heart rates. There was no increase in salivary cortisol levels, which can indicate stress.  


  • On to phase 2 of the study, all three groups of horses merged into one large group. Interestingly enough, the muzzled horses could not partake in normal grooming and biting behaviors, but the pecking order didn’t change. The continuously muzzled horses also lost weight, while the partially muzzled and unmuzzled horses gained weight. 


  • **It’s likely that the partially muzzled horses gained weight due to compensation. When the muzzles are removed, it’s time to gorge and play catch up. 


greenguard grazing muzzle on a halter

It’s a hay net that your horse wears. That is all. 


Take home message from this study


  • Horses wearing a muzzle in a herd environment have no detrimental side effects. Stress levels may lower in muzzled horses, as shown by their lower heart rates.  


  • Behaviors, such as time spent grazing and walking, varied for the muzzled horses, but the overall organization of the herd remained unchanged. 


One more benefit of grazing muzzles


  • Unmuzzled horses in this study walked 6% of the time. Muzzled horses walked 16% of the time spent out. This is great news for horses that need more movement in their lives. 


spotted horse wearing a greenguard muzzle in black


Be practical about using muzzles in a herd setting 


  • Introduce grazing muzzles gradually for any horse so they acclimate to eating with one and learn to associate the muzzle with good times on the grass.  


  • You may need to change the herd or adjust the halter if other horses interfere with it. It may also be possible to have muzzled and unmuzzled herds on a farm.


  • It’s not recommended that horses wear muzzles for 24 hours a day, so you may need to use dry lots or paddocks where your horse can use slow feeders. Depending on your farm’s facilities, some horse shuffling or schedules may be required.  

Every farm and herd will have different best-case scenarios! 

for more about this study:


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Safety break-away halter for grazing muzzles.



The best muzzle in the land – order one here! Also in raspberry and black colors.

Use code 15PROEQUINE for a lovely discount!

                                                     This fly mask is also great for use under grazing muzzles to prevent rubs. 

This slow feeder for pellets and grains helps your horse take his time eating. 

Another style of slow feeder for pellets and grains



EquiShure is a hindgut buffer that can help Cushing’s in horses as well as IR horses to balance their hindguts.

Equithrive Metabarol is also designed to support metabolic health


Quiessence is a supplement to reduce cresty necks, and may reduce the chance of founder. 


Heiro is designed to help horses with IR, which can happen with Cushing’s

Good reading if the hoof is fascinating to you!