Is Your Horse at Risk of Insulin-Related Laminitis?

Insulin-related laminitis is one of the most important preventable causes of painful hoof disease in horses, ponies and donkeys.

By Dr Duncan Houston

Laminitis is one of the most painful conditions a horse can develop. It can turn a normal horse into one that is reluctant to move, rocks back onto the hind limbs, shifts weight constantly, or cannot comfortably turn on a hard surface.

For years, many owners thought of laminitis as something caused mainly by grain overload, lush spring grass, concussion, or retained placenta. Those causes still matter, but we now understand that many modern laminitis cases are driven by insulin dysregulation, where the horse produces an exaggerated insulin response after eating sugars and starches.

This is often called insulin-related laminitis, endocrinopathic laminitis, or hyperinsulinemia-associated laminitis.

The good news is that many at-risk horses can be identified before disaster hits. The bad news is that the early warning signs are often ignored because the horse may look “just a bit chunky,” “a good doer,” or “a little footy.”

That is exactly when prevention matters most.

Quick Answer

A horse is more likely to be predisposed to insulin-related laminitis if they are an easy keeper, overweight, cresty-necked, have regional fat pads, have previous laminitis, have equine metabolic syndrome, have insulin dysregulation, have PPID, or belong to a higher-risk type such as ponies, donkeys, Arabians, mustangs, Morgans, Paso Finos, Warmbloods, and some other thrifty breeds. Insulin dysregulation is the key problem in equine metabolic syndrome, and high blood insulin can lead to hyperinsulinemia-associated laminitis. Diagnosis usually requires insulin testing, often with an oral sugar test or oral glucose test, because a normal resting insulin does not always rule out the problem. (Merck Veterinary Manual)

What Is Insulin-Related Laminitis?

Insulin-related laminitis is laminitis associated with high blood insulin concentrations.

Insulin is a hormone that helps move glucose from the bloodstream into tissues. In insulin-dysregulated horses, ponies and donkeys, the body produces too much insulin after eating non-structural carbohydrates, especially sugars and starches. Over time, or during sudden high-risk dietary exposure, this high insulin state can trigger laminitis. Merck Veterinary Manual describes insulin dysregulation as the key problem in equine metabolic syndrome and states that high blood insulin concentrations lead to laminitis, which can cause devastating lameness, loss of use and death. (Merck Veterinary Manual)

The exact biological pathway is still being researched. It is too simple to say insulin just “blocks blood flow” to the hoof. Current understanding is that sustained hyperinsulinemia affects the laminae through complex metabolic, cellular, vascular and growth-factor-related pathways. The clinically important point is simple: high insulin can damage the hoof laminae and cause laminitis. (Merck Veterinary Manual)

What Are the Laminae?

The laminae are the sensitive tissues that attach the hoof wall to the coffin bone inside the foot.

In a healthy hoof, the laminae hold the coffin bone suspended within the hoof capsule. In laminitis, these attachments become damaged and painful. In severe cases, the coffin bone can rotate or sink, which is the condition many owners call founder. Merck Veterinary Manual describes laminitis as inflammation and separation of the hoof laminae, with severe cases potentially causing rotation or sinking of the third phalanx, also called the coffin bone. (Merck Veterinary Manual)

That is why laminitis is not “just sore feet.” It is a structural failure risk inside the hoof.

What Is Equine Metabolic Syndrome?

Equine metabolic syndrome, or EMS, is a metabolic disorder strongly associated with insulin dysregulation and laminitis risk.

EMS commonly involves:

• Insulin dysregulation

• General obesity or regional fat deposits

• A cresty neck

• Fat pads around the tailhead, shoulders, ribs, sheath or mammary region

• Difficulty losing weight

• High laminitis risk

• A genetic or breed predisposition in many horses

UC Davis describes EMS as a disorder of inappropriate blood insulin regulation, often with increased regional fat deposition and reduced ability to lose weight. It also notes that affected horses are at high risk for laminitis, especially with access to pasture or high-carbohydrate feeds. (Center for Equine Health)

The Equine Endocrinology Group describes EMS as involving enhanced metabolic efficiency, increased adiposity, insulin resistance and hyperinsulinemia, with affected horses and ponies predisposed to laminitis. (Equine Endocrinology Group)

In plain English: some horses are designed to survive on very little. Put those horses on lush pasture, sweet feeds and limited exercise, and their metabolism can turn against their feet.

Which Horses Are Most at Risk?

1. Easy Keepers

Easy keepers are horses that gain weight easily and seem to live on air.

This is not just a cute personality trait. It can be a metabolic warning sign. UC Davis notes that EMS often affects thrifty equids such as ponies, donkeys, Arabians and mustangs that evolved to survive in harsh climates but become vulnerable when given abundant carbohydrates and limited exercise. (Center for Equine Health)

2. Ponies and Native-Type Breeds

Ponies are one of the highest-risk groups for insulin dysregulation and laminitis.

This includes many hardy, native or thrifty pony types. These animals may maintain or gain weight on relatively low feed intake, which is useful in harsh environments but risky in modern pasture systems.

3. Donkeys and Miniatures

Donkeys and miniature horses are also often metabolically efficient and can be prone to obesity and laminitis when fed like larger athletic horses.

4. Arabians, Mustangs, Morgans, Paso Finos and Warmbloods

The Equine Endocrinology Group lists ponies, Morgan horses, Paso Finos, Arabians and Warmbloods among breeds or types where EMS is more common and likely has a genetic component. (Equine Endocrinology Group)

This does not mean every horse in these groups is affected. It means these horses deserve earlier monitoring, especially if body condition, fat deposits or foot soreness are present.

5. Iberian and Spanish-Type Horses

Andalusians, Lusitanos and related Iberian types are commonly considered metabolically efficient and may be at increased risk, particularly when overweight or on high-sugar pasture.

6. Overweight Horses

Obesity increases risk, but it is not the whole story.

A horse with a body condition score above ideal, especially with a cresty neck or fat pads, deserves metabolic attention. UC Davis notes that many EMS horses are obese with body condition scores above 6 out of 9 and regional fat deposits, although insulin dysregulation can also occur in thinner animals. (Center for Equine Health)

7. Horses With Regional Fat Deposits

Some horses are not dramatically obese overall but still have suspicious fat deposits.

Watch for:

• Cresty neck

• Fat pads near the tailhead

• Fat behind the shoulders

• Fat behind the elbows

• Fat over the ribs

• Fat around the sheath or mammary area

The Equine Endocrinology Group notes that regional adiposity often develops in the neck and other areas, and that neck crest enlargement has been used as a physical marker for EMS. (Equine Endocrinology Group)

8. Horses With Previous Laminitis

A previous laminitis episode is one of the strongest reasons to test for insulin dysregulation and manage the horse as high risk.

These horses often need long-term pasture restriction, low-NSC forage, regular hoof care and periodic insulin monitoring.

9. Older Horses With PPID

Pituitary pars intermedia dysfunction, or PPID, can coexist with EMS and worsen insulin dysregulation.

Merck notes that abnormal PPID testing in a horse with EMS can indicate concurrent EMS and PPID, particularly in older horses, and that detecting PPID is important because PPID may exacerbate insulin dysregulation. (Merck Veterinary Manual)

Can a Lean Horse Still Have Insulin Dysregulation?

Yes.

This is one of the most important owner mistakes to avoid.

A horse does not need to be massively overweight to be insulin dysregulated. UC Davis specifically notes that insulin dysregulation can occur in thinner animals, and not every horse with a high body condition score has EMS. (Center for Equine Health)

This matters because leaner horses with regional fat deposits, previous laminitis, breed risk or abnormal insulin responses can be missed if everyone is only looking for a round belly.

The horse’s body shape helps you decide who to test. It does not replace testing.

What Triggers Insulin-Related Laminitis?

Common triggers include:

• Lush pasture

• Spring grass

• Autumn or fall grass

• Grass after rain and rapid regrowth

• Cool nights followed by sunny days

• Grass after frost

• Drought-stressed pasture

• High-starch grain

• Sweet feeds

• Molasses-containing feeds

• Sudden diet changes

• Obesity and lack of exercise

• Uncontrolled PPID

• Corticosteroid exposure in susceptible horses

• Illness, pain or stress in some cases

University of Minnesota Extension states that susceptible horses should have limited grazing or no grazing at all, and that sugar content is highest in immature grass, during cool nights with warm sunny days, after hard freeze and during drought conditions. (University of Minnesota Extension)

Is Pasture Really That Dangerous?

For some horses, yes.

Pasture is difficult because its sugar content changes constantly. It varies with weather, season, species, maturity, time of day and plant stress. Oregon State University Extension notes that laboratory testing is the only way to know if hay is low in non-structural carbohydrates, while pasture sugar testing is less reliable because pasture changes day to day and even by time of day. (OSU Extension Service)

For insulin-dysregulated horses, the safest pasture may be no pasture, at least during high-risk periods. Merck states that for EMS patients, grazing, grains and treats should be eliminated initially, and that decisions about returning to grazing depend on laminitis resolution, body condition and postprandial insulin response. (Merck Veterinary Manual)

That may sound strict, but laminitis is stricter.

What Is the Safest Time to Graze?

There is no completely safe grazing time for extremely sensitive horses.

In general, plant sugars tend to be lower in the early morning and higher later in the day. University of Minnesota Extension explains that grasses make and store sugars during daylight and use sugars overnight, so sugars are usually higher in the late afternoon and lower in the early morning. It recommends grazing susceptible horses between 3 a.m. and 10 a.m. when sugars are lower, while warning that very sensitive horses may need no grazing at all. (University of Minnesota Extension)

Do not graze susceptible horses after frost, during drought stress, during rapid spring regrowth or during cool sunny fall periods. Those conditions can increase sugar accumulation in pasture. (University of Minnesota Extension)

What Are the Early Signs of Insulin-Related Laminitis?

Early laminitis can be subtle.

Watch for:

• Short, pottery steps

• Reluctance to turn

• Soreness on hard ground

• Shifting weight

• Warm hooves

• Strong or bounding digital pulses

• Lying down more than normal

• Reluctance to walk forward

• Stiffness that looks like shoulder or arthritis pain

• Mild lameness in both front feet

• A “walking on eggshells” gait

• Increased sensitivity at the toe

• New or widening white line

• Hoof rings or changes in hoof growth

AAEP lists acute laminitis signs including lameness, shifting weight, heat in the feet, increased digital pulse and toe pain with hoof testers. Merck also describes severe lameness with bounding digital pulses as a hallmark clinical sign. (AAEP)

A key practical point: insulin-related laminitis may start quietly. The horse may not be dramatically crippled at first. That is when early action can save the feet.

How Worried Should You Be?

Low Risk

This is more likely when:

• The horse is lean and fit.

• There is no cresty neck.

• There are no abnormal fat pads.

• The horse has no laminitis history.

• The horse is not a high-risk breed or type.

• The horse is on a balanced, mostly forage-based diet.

• The horse exercises regularly.

• Insulin testing is normal.

Action: keep body condition appropriate, avoid excessive starch and sugar, monitor body shape and reassess if weight, pasture or workload changes.

Moderate Risk

This is more likely when:

• The horse is an easy keeper.

• The horse is mildly overweight.

• There is a developing neck crest.

• There are fat pads at the tailhead or shoulders.

• The horse is a pony, donkey, Morgan, Paso Fino, Arabian, Warmblood or other thrifty type.

• The horse is on pasture during spring or autumn.

• The horse is not exercised regularly.

• No insulin testing has been done.

Action: book a metabolic risk check. Adjust the diet before laminitis occurs. This is the best stage to act.

High Risk

This is more likely when:

• The horse has previous laminitis.

• The horse has a cresty neck or regional fat pads.

• The horse has confirmed insulin dysregulation.

• The horse has EMS or PPID.

• The horse is footsore after grass access.

• The horse has strong digital pulses or warm feet.

• The horse is overweight and grazing freely.

• The horse has abnormal hoof rings or a stretched white line.

Action: restrict pasture, remove high-sugar feeds, call your vet, test insulin, review the feet and involve a farrier. Radiographs may be needed even if lameness is mild.

Critical Risk

Treat this as urgent if:

• The horse is reluctant to move.

• The horse is shifting weight.

• The horse has hot feet and bounding digital pulses.

• The horse is lame in multiple feet.

• The horse is rocked back onto the hind limbs.

• The horse is lying down and reluctant to rise.

• There is a sudden change after pasture access.

• The horse has known EMS, PPID or previous laminitis and is now footsore.

Action: call your vet immediately. Remove pasture access, confine the horse on deep bedding or soft footing, and do not force exercise.

When Is This an Emergency?

Laminitis is an emergency.

Call your vet urgently if your horse has:

• Strong or bounding digital pulses

• Hot painful feet

• Reluctance to move

• Short, pottery gait

• Pain turning in circles

• Shifting weight

• Rocked-back stance

• Lameness in both front feet or all four feet

• Lying down more than normal

• Refusing to walk forward

• Sudden foot soreness after pasture access

• Previous laminitis and any new foot pain

The Royal Veterinary College states that laminitis is a medical emergency and that affected horses should be seen by a vet as soon as possible. It also notes that X-rays may be needed when there is concern about pedal bone rotation or sinking, or if the horse is not improving. (Royal Veterinary College)

Do not wait to see if laminitis “settles overnight.” The hoof does not forgive delayed decisions very well.

How Do Vets Diagnose Insulin Dysregulation?

Diagnosis is based on history, body condition, hoof assessment and blood testing.

Your vet may use:

• Body condition scoring

• Cresty neck scoring

• Hoof examination

• Digital pulse assessment

• Lameness exam

• Hoof radiographs

• Resting insulin

• Oral sugar test

• Oral glucose test

• Postprandial insulin testing

• ACTH testing for PPID in older or suspicious horses

Merck states that a single resting insulin measurement is only a screening test: a high value supports insulin dysregulation, but a low value does not exclude it. Merck also states that if baseline insulin is normal but suspicion remains, the horse’s response to oral carbohydrate should be tested with an oral sugar test or oral glucose test. (Merck Veterinary Manual)

What Is an Oral Sugar Test?

An oral sugar test, or OST, measures the insulin response after the horse receives a measured dose of corn syrup.

Merck describes the OST as fasting the horse for 3 to 6 hours, giving corn syrup at 0.15 to 0.45 mL/kg, then measuring insulin at 60 or 90 minutes. An insulin concentration of 45 mcIU/mL or higher is consistent with insulin dysregulation under the described testing conditions. (Merck Veterinary Manual)

This test is useful because some horses have normal resting insulin but produce an exaggerated insulin spike after sugar exposure. Those are often the horses owners miss.

What Is an Oral Glucose Test?

An oral glucose test, or OGT, measures insulin after a controlled dose of glucose or dextrose powder.

Merck describes the OGT as giving a fasted horse 0.75 g/kg of dextrose powder mixed with chaff, then measuring insulin 2 hours later. An insulin concentration of 65 mcIU/mL or higher is consistent with insulin dysregulation. (Merck Veterinary Manual)

Your vet will choose the best test based on the horse, lab, region, available assays and clinical situation.

Why Blood Glucose Alone Is Not Enough

Do not rely on glucose alone.

Most EMS horses have normal or only slightly increased blood glucose. Merck states that blood glucose concentrations have no diagnostic value for EMS because they are usually normal or only mildly increased, and that persistent hyperglycemia should raise suspicion for concurrent PPID. (Merck Veterinary Manual)

This is why owners may be falsely reassured by a normal glucose result. The problem is often insulin, not glucose.

Should Hoof X-Rays Be Done?

Often, yes, especially if there is any foot soreness, previous laminitis, stretched white line, hoof rings, abnormal hoof shape or digital pulse change.

Merck recommends careful examination of the feet in EMS cases and lateromedial radiographs of the pedal bones even when there is no laminitis history. It also notes that hyperinsulinemia-associated laminitis can occur without obvious lameness and that radiography is recommended to detect hoof distortion. (Merck Veterinary Manual)

That is a very important point.

A horse can be metabolically high risk and already have hoof changes before the owner recognises a major laminitis episode.

How Is Insulin-Related Laminitis Prevented?

Prevention is built around three big goals:

1. Reduce insulin spikes

2. Maintain healthy body condition

3. Protect the feet

The core tools are diet, pasture restriction, exercise, testing and hoof care.

Diet: The Most Important Step

Diet is the most important part of EMS management. Merck states that dietary adjustment is sufficient to manage most cases, and that for EMS patients, grazing, grains and treats should initially be eliminated. It recommends low-NSC hay at around 10% non-structural carbohydrates by feed analysis, fed in slow feeders or multiple small meals. (Merck Veterinary Manual)

Practical diet steps include:

• Remove sweet feed

• Remove molasses

• Avoid corn, oats and high-starch grain

• Avoid sugary treats

• Use tested low-NSC hay

• Feed a ration balancer if needed

• Use a slow feeder

• Divide forage into multiple meals

• Do not starve the horse

• Keep the diet consistent

For a horse with insulin dysregulation, boring feed is usually safer feed.

How Much Hay Should You Feed?

For many horses, forage is fed as a percentage of body weight, but this should be based on ideal or target body weight, not always current body weight.

Merck recommends low-NSC hay at 2% of body weight for horses with a body condition score of 5 out of 9, and decreasing to 1.5% of body weight in obese horses. It also warns that severe restriction can be detrimental and increase hyperlipemia risk. (Merck Veterinary Manual)

This is not a crash diet situation. It is a controlled weight loss and insulin management plan.

Should Hay Be Tested?

Yes, especially in confirmed or suspected insulin dysregulation.

Oregon State University Extension states that laboratory testing is the only way to know if hay is low in sugars, and recommends choosing forage below 10% NSC for horses requiring a low-sugar diet, or following veterinary direction. (OSU Extension Service)

Looking at hay does not tell you its sugar content. Smelling it, squeezing it and asking the seller if it is “horse quality” does not count either. Very scientific. Not very useful.

Does Soaking Hay Help?

It can help, but it is not perfect.

Oregon State University Extension states that soaking hay for 15 to 60 minutes can reduce NSC concentration, but results vary and soaking can also leach valuable minerals. Merck similarly lists soaking hay for 60 minutes as one strategy to decrease NSC content. (OSU Extension Service)

If hay is soaked long-term, the horse may need a properly balanced vitamin and mineral supplement because minerals can leach into the water.

Should Pasture Be Removed Completely?

For high-risk horses, often yes.

Merck states that EMS horses almost always require severe grazing restriction, especially during high-soluble carbohydrate periods such as spring and autumn. (Merck Veterinary Manual)

Options include:

• Dry lot turnout

• Track system with low-NSC forage

• Grazing muzzle in selected horses

• Very limited turnout windows

• Avoiding stressed grass

• Avoiding spring and autumn high-risk periods

• Avoiding pasture after frost

• Monitoring insulin response if grazing is reintroduced

University of Minnesota Extension warns that extremely sensitive horses may have no completely safe time to graze. (University of Minnesota Extension)

Do Grazing Muzzles Work?

Grazing muzzles can reduce intake, but they do not make pasture automatically safe.

University of Minnesota Extension recommends grazing muzzles as one option to limit forage intake when pasture is the horse’s main exercise source. (University of Minnesota Extension)

Use them carefully. Check for rubs, ensure the horse can drink, make sure the fit is safe and remember that very sensitive laminitic horses may still need no pasture at all.

Exercise and Insulin Sensitivity

Exercise can improve insulin regulation, but only when the horse is sound enough.

Merck states that after laminitis has resolved, exercise helps improve insulin sensitivity by building muscle and reducing fat. It gives an example of walking and trotting 5 days per week improving insulin regulation, while stressing that exercise should not be increased if the horse becomes lame. (Merck Veterinary Manual)

That last line matters.

Do not exercise a horse through active laminitis. Once the feet are comfortable and stable, exercise becomes one of the best long-term tools.

What About Supplements Like Magnesium, Chromium and Cinnamon?

Be careful.

These supplements are popular, but they are not magic insulin fixes. Merck states that cinnamon, chromium and magnesium have been suggested for EMS, but none have been shown to improve insulin regulation in horses in experimental situations. UC Davis says the same and notes that mineral supplementation is still important when hay is soaked because minerals can leach out with soluble carbohydrates. (Merck Veterinary Manual)

A supplement should never be used as an excuse to keep feeding pasture, sweet feed or high-NSC forage to an insulin-dysregulated horse.

The best “metabolic supplement” is still an appropriate diet.

Annoying, but true.

Are Medications Ever Used?

Sometimes, but they are not first-line replacements for diet.

Merck states that no drug is currently labeled for managing insulin dysregulation in horses, and no drug should be used without a proper diet. It notes that SGLT2 inhibitors have shown promising results in managing hyperinsulinemia and hyperinsulinemia-associated laminitis, while metformin has variable effects and is poorly absorbed in horses. (Merck Veterinary Manual)

Medication decisions belong with your veterinarian, especially in severe, refractory or acute laminitis cases.

What Should You Do Right Now?

If your horse may be at risk:

1. Score the Body Condition

Use a 1 to 9 body condition scale. Aim for a moderate score, usually around 5 out of 9, unless your vet recommends otherwise.

2. Check the Neck Crest

A thick, hard or enlarged crest is a major warning sign, even if the horse does not look obese everywhere else.

3. Look for Regional Fat Pads

Check the tailhead, shoulders, ribs, sheath or mammary region and behind the elbows.

4. Review the Diet

Write down everything the horse eats:

• Hay type

• Pasture access

• Grain

• Chaff

• Balancer

• Treats

• Supplements

• Hay amount

• Feeding frequency

5. Remove Obvious High-Risk Feed

Cut out sweet feeds, molasses, high-starch grain and sugary treats while you arrange proper veterinary advice.

6. Restrict Pasture if Risk Is Moderate or High

Use a dry lot, track system, muzzle or restricted turnout plan depending on risk level. High-risk horses may need no grazing.

7. Test Insulin

Ask your vet about resting insulin, oral sugar testing, oral glucose testing and PPID testing if your horse is older or suspicious.

8. Check the Feet

Feel digital pulses, assess hoof warmth, look for hoof rings and check whether your horse is sore on hard ground or turning.

9. Involve Your Farrier

High-risk horses need excellent hoof balance. Merck recommends regular experienced farrier care, and in at-risk EMS cases, trimming every 4 weeks may be recommended. (Merck Veterinary Manual)

10. Call Your Vet Immediately if Foot Pain Appears

Do not exercise a footsore horse. Do not wait. Do not try to “walk it off.”

What Not To Do

Avoid these common mistakes:

• Do not assume a lean horse cannot have insulin dysregulation.

• Do not wait for obvious founder before testing.

• Do not rely on glucose alone.

• Do not keep a high-risk horse on lush pasture because they “need to be a horse.”

• Do not mow grass and assume it is safe.

• Do not use supplements as a substitute for diet control.

• Do not exercise during active laminitis.

• Do not feed grain because the horse “needs energy” unless the ration is vet-approved.

• Do not ignore a cresty neck.

• Do not forget PPID testing in older horses.

• Do not assume barefoot or shoes alone will prevent laminitis.

The biggest mistake is treating insulin-related laminitis as a hoof-only problem. The hoof is where the pain appears, but the trigger is often metabolic.

Can Mowing Reduce Pasture Sugar Enough?

No, mowing is not a reliable safety strategy.

Pasture sugar content depends on plant species, stress, growth stage, weather, time of day and season. Oregon State University Extension states that fresh pasture sugar testing is less reliable than hay testing because pasture changes day to day and by time of day. University of Minnesota Extension also notes that the lower part of the plant may contain the highest sugar, so overgrazed or very short grass can still be risky. (OSU Extension Service)

A lawnmower is not a metabolic management plan. Bit rude, but accurate.

How Often Should Insulin Be Rechecked?

This depends on the horse, test results and risk level.

Rechecking may be useful:

• After diet change

• After weight loss

• Before reintroducing pasture

• During spring and autumn risk periods

• After a laminitis episode

• If hoof soreness returns

• If PPID is diagnosed or suspected

• If body condition changes

Merck recommends postprandial insulin measurement to monitor diagnosed cases and assess whether the horse can metabolise its current hay or pasture diet appropriately. It states that insulin at or below 50 mcIU/mL suggests an acceptable response and low laminitis risk under that management, while 100 mcIU/mL or higher indicates inadequate management and high laminitis risk. (Merck Veterinary Manual)

Your vet will interpret values using the lab, assay and clinical context.

Prevention: The Practical Checklist

To reduce insulin-related laminitis risk:

• Keep body condition moderate.

• Test insulin in at-risk horses.

• Test older horses for PPID when appropriate.

• Use low-NSC forage for high-risk horses.

• Test hay rather than guessing.

• Remove sweet feed, molasses and high-starch grain.

• Restrict or eliminate pasture in high-risk horses.

• Avoid pasture after frost, during drought, during spring flush and during cool sunny autumn periods.

• Use slow feeders to reduce meal size and extend eating time.

• Exercise regularly once the horse is sound.

• Keep farrier care consistent.

• Take hoof radiographs when laminitis risk or hoof distortion is present.

• Recheck insulin after major management changes.

• Do not rely on supplements alone.

Merck summarises EMS prevention as maintaining normal weight, feeding appropriately for each individual and exercising particular care with pasture during high-soluble carbohydrate periods. (Merck Veterinary Manual)

Case Example: Pony With Lush Grass Laminitis

A 12-year-old Welsh pony becomes pottery and reluctant to turn after several weeks on spring pasture. The owner notices a thick neck crest, fat pads near the tailhead and stronger digital pulses in both front feet.

Radiographs show mild rotation. Blood testing confirms high insulin. The pony is moved to a dry lot, sweet feed is removed, and a tested low-NSC hay diet is started in a slow feeder. The farrier and vet work together on hoof support and a trim plan. Once the pony is comfortable and the feet are stable, controlled exercise is introduced.

The lesson is simple: the foot pain was the emergency, but insulin control was the long-term treatment.

Myth vs Reality

Myth	Reality
“Only fat horses get insulin-related laminitis.”	Leaner horses can still have insulin dysregulation, especially with regional fat deposits or breed risk.
“Normal glucose means the horse is fine.”	Glucose is often normal in EMS. Insulin testing is the key.
“A cresty neck is just cosmetic.”	A cresty neck can be a major metabolic warning sign.
“Early morning pasture is always safe.”	It may be lower risk, but very sensitive horses may need no grazing at all.
“Mowing grass makes it safe.”	Short or stressed grass can still be high risk.
“Magnesium, chromium or cinnamon will control insulin.”	These have not been shown to improve insulin regulation in experimental horse studies.
“Laminitis is a hoof problem.”	The hoof is damaged, but the trigger is often metabolic.

FAQs About Insulin-Related Laminitis

Can a horse have insulin-related laminitis without being obese?

Yes. Many affected horses are overweight, but insulin dysregulation can occur in thinner horses. Regional fat deposits, previous laminitis, breed type and insulin testing matter more than appearance alone. (Center for Equine Health)

What breeds are most at risk?

Ponies, donkeys, Arabians, mustangs, Morgans, Paso Finos, Warmbloods and other thrifty types are commonly considered higher risk, especially when overweight or on high-NSC diets. (Center for Equine Health)

What is the best test for insulin dysregulation?

Resting insulin can be a useful screening test, but a normal result does not rule out insulin dysregulation. Oral sugar testing or oral glucose testing is often needed when suspicion remains. (Merck Veterinary Manual)

What hay is safest for insulin-resistant horses?

Tested hay with less than 10% NSC is commonly recommended for horses needing a low-sugar diet. Hay testing is much more reliable than judging hay by appearance. (OSU Extension Service)

Should I exercise my horse if laminitis is suspected?

No. Do not exercise a horse with active laminitis or new foot soreness. Call your vet, restrict movement, provide soft footing or deep bedding and wait for veterinary guidance. Exercise becomes useful only after laminitis has resolved and the horse is comfortable. (Merck Veterinary Manual)

The Bottom Line

Insulin-related laminitis is common, painful and often preventable.

The horses most at risk are usually the ones that look like they are thriving: easy keepers, ponies, hardy breeds, horses with cresty necks, horses with fat pads, and horses that gain weight on pasture while doing very little work.

The dangerous mistake is waiting until the horse is obviously lame. By then, the laminae may already be damaged.

The safest approach is proactive:

• Identify risky body types early.

• Test insulin before laminitis occurs.

• Control pasture and dietary sugar.

• Keep body condition moderate.

• Use tested forage.

• Exercise only when feet are sound.

• Check for PPID in older horses.

• Keep farrier care tight.

• Treat any foot soreness as urgent.

Insulin-related laminitis is not about blaming the owner or blaming the grass. It is about recognising that some horses are metabolically wired for scarcity, but living in a world full of calories.

That mismatch can hurt their feet. Your job is to spot the risk before the hooves pay the price.

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If your horse has a cresty neck, regional fat pads, previous laminitis, pasture sensitivity, or possible insulin dysregulation, ASK A VET™ can help you organise the signs, diet history, photos and questions to discuss with your vet before it becomes a hoof emergency.