Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find the latest question and answer installment that you can share with your footcare clients.
Q: With my laminitis-prone mare, I’m using a grazing muzzle to limit feed intake with early-spring grazing. Should I be concerned about proper adjustment to avoid tooth damage?
By Joyce Harman, DVM
A: Muzzles are often accused of damaging the horse’s front teeth. While this can be true, it's important to put it in the correct context.
A grazing muzzle prevents a horse from overeating grass, which can save her life, or at least save the horse a bad case of laminitis and the owner thousands of dollars in veterinarian bills. However, as with everything in life, a bit of knowledge and common sense will make wearing a muzzle much less damaging.
Horses that crib or run their teeth on bars in the stall often wear their teeth much more than what occurs with a muzzle, yet muzzles often get the blame for tooth damage.
Because the muzzle restricts the amount of grass the horse can put in her mouth at one time, some horses become frustrated. This can cause stress, leading to increases in ulcers and can increase insulin resistance (IR), which is well-documented in human medicine for stress.
If your horse shows signs of being uncomfortable after eating, has a poor coat or any digestive issues, it might be useful to put her on some herbs or probiotics for ulcers.
Another way a horse displays stress is by pushing harder against the ground while trying to eat to more. These horses are most likely to wear their teeth, especially if an adjustable muzzle is used. It is important to adjust the number of holes available to each horse depending on its size or the amount of grass in the field. Some muzzles do not have the ability to change the size or number of holes, so if the grass is sparse, the horse will try harder to eat more forage.
The muzzle material also plays a role in teeth wear. While the traditional rubber sounds soft on the teeth, the horse is pushing it against the ground as she grazes. Rubber does give a little and wears easily. I see many rubber muzzles where the hole is two to three times larger than it's supposed to be, so there’s no restriction in grass intake.
Plastic muzzles are made from variable hardness plastics. If the horses push hard against the ground, they will wear it out eventually and will wear down their teeth to some extent. Hard plastic muzzles will wear the teeth faster and may not wear out as easily.
However, if the horse grazes quietly and accepts the muzzle without applying too much pressure, even the harder plastic models will work fine. Soft plastic may just wear out rapidly unless the horse is easy on it.
When selecting a muzzle or complaining to the manufacturer about wear, first determine if your horse is grazing with gusto, applying lots of pressure or just moving quietly across the grass while eating. Be sure there is enough of an opening so the horse can get enough grass to satisfy herself without eating too much. The single hole in the center of some muzzles is not enough for most horses, but having too many holes across the bottom may not be restrictive enough.
Dr. Joyce Harman owns Harmany Equine Clinic, Ltd., a holistic veterinary practice located in Washington, Va.
Hoof Nutrition Intelligence is brought to you by W.F. Young Co. (Absorbine). 
Like many significant achievements, Absorbine® grew out of humble beginnings—and through the tenacity of someone willing to question the status quo. In this case, it was a young woman in late 19th-century Massachusetts: Mary Ida Young. Her husband, Wilbur Fenelon Young, was an enterprising piano deliveryman who relied on the couple’s team of horses to make deliveries throughout the Northeast. Inspired by Mary Ida and Wilbur’s vision, Absorbine® has continued to add innovative products throughout the years — products used every day by horse owners around the world. Which is why, since 1892, we’ve been The Horse World’s Most Trusted Name®.
Click here to read more installments of Hoof Nutrition Intelligence.