Feeding Horses with Pasture-Associated Laminitis

Feeding Horses with Pasture-Associated Laminitis

By Dr Duncan Houston

Pasture looks natural, and for many horses it is. For horses with insulin dysregulation, Equine Metabolic Syndrome, PPID, obesity, or a history of laminitis, pasture can be one of the most dangerous parts of the diet. That is because grass is not just fiber. Under the wrong conditions, it can deliver enough rapidly available carbohydrate to trigger serious metabolic and hoof consequences.

This is where owners often get caught out. They worry about grain and treats while underestimating the risk sitting in the paddock. In many horses, pasture is the real problem. Managing pasture-associated laminitis properly means understanding which horses are at risk, when grass becomes more dangerous, and how to build a feeding plan that protects the feet without starving the horse.

Quick Answer

Pasture-associated laminitis happens when grass intake, especially high non-structural carbohydrate intake, triggers a harmful metabolic response in a horse that is already susceptible. The safest feeding plan usually involves restricting or removing pasture access, feeding tested low-NSC hay, using a ration balancer where needed, and controlling total calorie intake carefully. For at-risk horses, guessing is risky. A structured forage plan matters far more than simply “cutting back a bit.”

What Is Pasture-Associated Laminitis?

Laminitis is inflammation and structural failure within the laminae of the hoof. In pasture-associated cases, the trigger is usually not grain overload but carbohydrate intake from grass in a horse that is metabolically vulnerable.

These horses commonly include:

• easy keepers

• overweight horses

• ponies and hardy breeds

• horses with Equine Metabolic Syndrome

• horses with insulin dysregulation

• horses with PPID

• horses with a previous history of laminitis

The important point is that pasture does not have to look lush or dramatic to be dangerous. A horse with the wrong metabolism can react badly to pasture that another horse tolerates easily.

Why Grass Can Be So Risky

Grass contains non-structural carbohydrates, including:

• sugars

• fructans

• starches

These levels can change based on:

• sunlight

• temperature

• drought stress

• frost

• plant species

• growth stage

• time of day

That variability is what makes pasture so tricky. Owners often assume that “natural” means safe. It does not. In a horse with insulin problems, natural pasture can be more dangerous than a carefully controlled hay-based diet.

Which Horses Are Most at Risk?

Some horses are far more likely to develop pasture-associated laminitis.

Higher-risk horses include:

• obese horses

• easy keepers

• horses with a cresty neck or regional fat pads

• horses with Equine Metabolic Syndrome

• horses with PPID

• horses with known insulin dysregulation

• horses with previous laminitis

Decision checkpoint

If your horse has had laminitis before, you should assume pasture access needs active management unless your vet has clearly advised otherwise.

Why Timing of Grazing Matters

Pasture sugar levels are not constant across the day. In many conditions, levels are lower earlier in the day and rise after sunlight-driven photosynthesis. That means grazing risk can increase later in the day.

This matters because some owners try to manage laminitis risk simply by limiting turnout time without considering when the horse is grazing.

That said, timing helps only at the margins. It does not make unsafe pasture truly safe for a high-risk horse.

Why Simple Time Restriction Often Fails

A common strategy is to allow limited pasture access and assume that a short turnout window means low intake. The problem is that many horses compensate by eating very quickly.

That means:

• short access does not always equal low intake

• hungry horses may binge graze

• highly motivated easy keepers can consume a surprising amount very quickly

In practice, time restriction alone is often not enough for higher-risk horses. The horse’s behavior matters just as much as the clock.

How Worried Should You Be?

Low risk

• healthy horse

• normal body condition

• no metabolic history

• no previous laminitis

Action: Routine pasture management is usually enough.

Moderate risk

• easy keeper

• overweight

• mild fat pads

• uncertain metabolic status

Action: Tighten diet control and consider testing, weight management, and more careful turnout planning.

High risk

• diagnosed Equine Metabolic Syndrome

• insulin dysregulation

• PPID with metabolic instability

• previous laminitis

Action: Restrict pasture heavily or remove access entirely unless a very controlled plan is in place.

Critical risk

• active laminitis

• recent laminitis flare

• ongoing foot pain

• unstable metabolic disease

Action: This is not the time for trial-and-error grazing. Pasture access often needs to stop while the horse is stabilized under veterinary guidance.

What Does a Safer Feeding Plan Look Like?

For many laminitis-prone horses, the safest foundation is not pasture. It is controlled forage.

A safer plan often includes:

• low-NSC hay

• tested hay where possible

• soaked hay when appropriate

• controlled portions

• a dry lot or restricted turnout area

• a low-NSC ration balancer if nutrients are missing

• careful bodyweight monitoring

The goal is not simply to feed less. It is to feed in a way that lowers insulin stress while still supporting gut health.

Why Hay Quality Matters So Much

Owners sometimes remove grain but keep feeding whatever hay is available. That can still go badly wrong.

Hay matters because:

• NSC content can vary widely

• some hay is too sugary for high-risk horses

• mature-looking hay is not automatically safe

• one batch can differ from the next

For many at-risk horses, hay under about 10 percent NSC is the target, though the exact threshold depends on the individual case.

Decision checkpoint

If you do not know the NSC of your hay and your horse has metabolic disease or laminitis history, you are still making a significant gamble.

Should You Soak Hay?

Soaking hay can help reduce water-soluble sugars in some cases. It is not a perfect solution, but it can be useful when:

• the hay is close to an acceptable range

• a safer hay source is not available

• the horse is high risk and every reduction matters

It is less helpful when:

• the starting hay is very high in NSC

• owners assume soaking makes any hay safe

• hygiene and handling are poor

Soaking is a tool, not a guarantee.

Feeding Frequency and Insulin Control

Large meals can create bigger post-feeding insulin responses than smaller, more evenly distributed forage intake.

For many high-risk horses, a better pattern is:

• smaller hay meals

• more frequent feeding intervals

• slow feeders to spread intake

• avoiding long fasting periods followed by gorging

This helps because a hungry horse that bolts feed is more likely to have unstable intake patterns and management becomes harder.

What About Grain and Concentrates?

For many horses with pasture-associated laminitis risk, grain should be minimized or avoided unless there is a very specific reason for using it.

Common problems include:

• unnecessary starch load

• hidden sugar in commercial feeds

• overfeeding “just a little” concentrate

• confusing a balancer with a typical hard feed

If nutrients are needed, a low-intake ration balancer is often more appropriate than a traditional grain meal.

Are Grazing Muzzles Useful?

Yes, in many cases.

Grazing muzzles can significantly reduce pasture intake and are often very useful for:

• easy keepers

• overweight horses

• horses needing controlled turnout

• owners trying to preserve some turnout time without full pasture access

But they are not perfect.

They still require:

• correct fit

• regular skin checks

• monitoring for rubs

• awareness that some horses learn to outsmart them

• understanding that reduced intake is not the same as zero intake

For some horses, a muzzle is a helpful compromise. For others, a dry lot is safer.

Dry Lots and Restricted Turnout

A dry lot is often one of the safest options for horses with strong laminitis risk because it removes the unpredictability of pasture.

A good dry lot plan still needs:

• enough forage to support gut health

• movement where possible

• low-NSC hay

• boredom reduction and enrichment

• proper hoof and weight monitoring

The mistake is thinking a dry lot is just “no grass.” It still needs to be managed well.

Common Mistakes Owners Make

Assuming a little pasture is harmless

For some horses, a little is enough to trigger a flare.

Trusting appearance

Short grass, winter grass, or sparse grass can still be risky.

Restricting time without controlling intake

Some horses compensate by binge grazing.

Feeding untested hay

Hay can quietly maintain the problem even after pasture is restricted.

Overlooking body condition

Crestiness, fat pads, and gradual weight gain are important warning signs.

Treating every horse the same

One horse may tolerate pasture. Another may not.

What To Do Right Now

1. Identify whether your horse is metabolically at risk

2. Restrict or remove pasture access if risk is high

3. Test hay if possible, especially for NSC

4. Use low-NSC forage as the diet foundation

5. Consider a grazing muzzle or dry lot where appropriate

6. Monitor body condition, digital pulses, and foot comfort closely

In these horses, prevention is much easier than trying to recover from another laminitis flare.

Pasture-Associated Laminitis Feeding Plan at a Glance

When Is This an Emergency?

This becomes urgent when a horse shows:

• foot pain

• reluctance to move

• rocked-back stance

• heat in the feet

• strong digital pulses

• sudden soreness after pasture exposure

At that point, the issue is no longer just “feeding advice.” It is a laminitis case and should be treated as such.

FAQs

Can pasture really cause laminitis more often than grain?

Yes. In many at-risk horses, pasture is a more common trigger than people realize.

Is early morning grazing always safe?

No. It may be lower risk in some situations, but it is not universally safe for high-risk horses.

Can a grazing muzzle fully prevent laminitis?

No. It can reduce intake, but it does not remove risk completely.

Do all horses with PPID need pasture restriction?

Not always to the same degree, but many do need careful control, especially if insulin dysregulation is also present.

Is low-NSC hay usually safer than pasture?

For many high-risk horses, yes. Controlled low-NSC hay is often safer and more predictable.

Final Thoughts

Pasture-associated laminitis is one of the clearest examples of how “natural” is not always safe. A susceptible horse does not care that the feed came from grass instead of a bucket. What matters is the carbohydrate load reaching a system that cannot handle it properly.

The safest approach is usually simple in principle: know the horse’s risk, control pasture access seriously, use low-NSC forage, and stop guessing. In horses prone to laminitis, the paddock should be managed like a medical risk factor, because that is exactly what it is.

If you are unsure whether your horse’s pasture access is safe, or how to build a lower-risk feeding plan for EMS, PPID, or laminitis history, ASK A VET™ can help you think through the next step clearly.