How To Prevent Founder in Horses With EMS

How To Prevent Founder in Horses With EMS

By Dr Duncan Houston

Founder is one of the most frightening words in horse care.

It is painful, expensive, slow to manage, and in severe cases it can permanently damage the hoof. The frustrating part is that many cases linked to equine metabolic syndrome are preventable, or at least greatly reduced, when the risk is recognised early.

The biggest warning sign is not always obvious lameness. It may be the easy keeper with a cresty neck, fat pads, repeated spring foot soreness, or “just a bit pottery” movement after pasture access.

That horse is waving a metabolic red flag.

Quick Answer

To prevent founder in horses with equine metabolic syndrome, the main goal is to control insulin dysregulation and reduce laminitis triggers. That usually means tested low-NSC hay, calorie control, reduced or eliminated pasture access, weight loss if overweight, exercise only when sound, regular farrier care, and veterinary monitoring of insulin and PPID risk. UC Davis recommends NSC restriction, calorie restriction, and reduced or eliminated pasture access as core EMS management, with hay ideally below 10% NSC on a dry matter basis. (Center for Equine Health)

If your horse is suddenly footsore, reluctant to walk, rocked back, has heat in the feet, or has strong digital pulses, treat it as an emergency and call your vet.

Founder vs Laminitis: What Is the Difference?

Owners often use “founder” and “laminitis” interchangeably.

Technically, laminitis is inflammation and failure of the laminae, the sensitive tissues that attach the coffin bone to the hoof capsule. Founder is often used when laminitis has progressed to structural displacement, such as rotation or sinking of the coffin bone.

The practical point is simple: laminitis is the warning, founder is the disaster we are trying to prevent.

Merck describes laminitis as inflammation and separation of the laminae of the hoof, with severe cases risking rotation or sinking of the coffin bone. The hallmark clinical sign is severe lameness with bounding digital pulses. (Merck Veterinary Manual)

This is why early management matters so much. Once the hoof structures are damaged, the horse may need months of treatment, radiographs, corrective farriery, pain control, diet restriction, and long-term monitoring.

What Is Equine Metabolic Syndrome?

Equine metabolic syndrome, or EMS, is a collection of risk factors that makes horses more likely to develop endocrinopathic laminitis.

The central problem is insulin dysregulation. These horses produce an abnormal insulin response after eating certain carbohydrates, especially sugars and starches. They often have increased fat deposits, a cresty neck, difficulty losing weight, and a high risk of laminitis. UC Davis notes that EMS commonly affects thrifty equids such as ponies, donkeys, Arabians, and mustangs, although any horse can be affected. (Center for Equine Health)

Typical EMS warning signs include:

• Easy weight gain

• Cresty neck

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

• Difficulty losing weight

• Recurrent foot soreness

• Laminitis history

• Stronger reaction to pasture or high-carbohydrate feed

• Normal-looking horse but abnormal insulin testing

Not every EMS horse is hugely overweight. Some thinner horses can still have insulin dysregulation, especially if PPID is also present. That is why blood testing matters.

Why Insulin Dysregulation Causes Laminitis Risk

In EMS, the horse’s insulin response becomes abnormal. After eating sugar or starch, insulin may rise too high, stay high too long, or both.

High insulin is strongly linked with endocrinopathic laminitis risk. The exact biology is complex, but clinically the message is very clear: horses with insulin dysregulation are more likely to develop laminitis, especially when exposed to pasture, high-NSC hay, grain, sweet feed, or sudden carbohydrate changes. Merck states that endocrine dysfunction is probably the most common underlying cause of laminitis in horses today, with hyperinsulinemia thought to be the predisposing condition. (Merck Veterinary Manual)

So the prevention plan is not just about making the horse thinner.

It is about reducing insulin spikes, reducing total metabolic stress, protecting the feet, and monitoring the horse before pain appears.

Early Signs of Laminitis

Early laminitis can be subtle.

Watch for:

• Short, careful steps

• Reluctance to turn

• Reluctance to walk on hard ground

• Shifting weight

• Lying down more than normal

• Heat in the hooves

• Strong or bounding digital pulses

• Stiffness after pasture access

• A pottery gait

• Rocking weight back onto the hindlimbs

• Refusal to lift one foot because the other feet hurt

The classic severe picture is the rocked-back horse with obvious pain and bounding pulses, but not every case starts dramatically. Mild soreness after pasture can still be laminitis until proven otherwise.

If your horse has EMS risk and becomes footsore, do not “give it a few days.” Get the vet involved early.

Risk Framework: How Worried Should You Be?

Low Risk

This is lower risk if your horse:

• Has ideal body condition

• Has no cresty neck

• Has no laminitis history

• Has normal insulin testing

• Maintains weight easily without becoming fat

• Eats tested appropriate forage

• Has controlled pasture access

• Exercises regularly and is sound

This horse still needs monitoring, but the current plan may only need routine checks.

Moderate Risk

This is more concerning if your horse:

• Is an easy keeper

• Has mild fat pads

• Has a slight crest

• Gains weight every spring or autumn

• Has unrestricted pasture access

• Has not had insulin testing

• Has not had hay tested

• Is fed grain or sweet feed without a clear need

This is the stage where prevention should start. Waiting for laminitis is like waiting for smoke before installing the fire alarm.

High Risk

This is high risk if your horse:

• Is overweight or obese

• Has a firm cresty neck

• Has regional fat pads

• Has confirmed insulin dysregulation

• Has EMS

• Has PPID with high insulin

• Has previous laminitis

• Is footsore after pasture

• Is eating untested hay or pasture

• Is getting grain, molasses, or high-starch concentrates

This horse needs a veterinary-guided EMS and laminitis prevention plan.

Critical

This is urgent if your horse:

• Is suddenly lame

• Is reluctant to walk

• Rocks back onto the hindlimbs

• Has heat in the hooves

• Has strong digital pulses

• Lies down more than normal

• Refuses to turn

• Has severe pain

• Has signs of colic, fever, diarrhoea, or systemic illness

• Has known EMS or PPID and any new foot soreness

This is a vet-now situation.

When Is Founder an Emergency?

Treat suspected laminitis or founder as an emergency.

Call your vet urgently if your horse has:

• Sudden foot pain

• A pottery or stilted gait

• Reluctance to walk or turn

• Heat in the hooves

• Strong digital pulses

• A rocked-back stance

• Repeated lying down

• Refusal to pick up feet

• Severe pain

• Depression or sweating

• Previous laminitis with any new soreness

Merck describes laminitis as one of the most important and catastrophic diseases in horses, with outcomes ranging from temporary loss of use to life-threatening disease. (Merck Veterinary Manual)

Do not exercise a horse with active laminitis. Do not turn them out on pasture “to loosen up.” Do not wait until they are unable to move.

Early pain control, foot support, diet control, radiographs, and farriery can change the outcome.

What Else Can Cause Laminitis?

EMS is a major cause, but it is not the only cause.

Important causes and rule-outs include:

• Equine metabolic syndrome

• PPID

• Insulin dysregulation

• Grain overload

• Sudden access to lush pasture

• Retained placenta after foaling

• Severe colitis or enteritis

• Endotoxaemia

• Severe infection

• Supporting-limb laminitis after injury to the opposite leg

• Excess body weight

• Certain toxin exposures

• Some corticosteroid-associated cases in predisposed horses

This is why every laminitis case deserves more than “cut the feed.” You need to know whether the horse has EMS, PPID, systemic illness, grain overload, or another trigger.

How Is EMS Diagnosed?

EMS diagnosis is based on the horse’s history, body condition, physical examination, and diagnostic testing.

Common tests include:

• Resting insulin

• Resting glucose

• Oral sugar test

• Oral glucose test

• Insulin tolerance test in some settings

• Leptin in some cases

• ACTH testing if PPID is suspected

Cornell lists insulin, the oral sugar test, and leptin as recommended tests for EMS diagnosis and follow-up, and notes that EMS and PPID can occur separately or together. (Cornell Vet School)

A single normal insulin result does not always rule out insulin dysregulation. Some horses need dynamic testing, especially if the clinical picture screams EMS but resting values are borderline.

If your horse is cresty, overweight, laminitis-prone, or reacts badly to pasture, testing is not overkill. It is how you stop guessing.

What Should You Do Next?

1. If the Horse Is Footsore, Call the Vet First

If there is any suspicion of active laminitis, the priority is pain control, foot support, confinement, radiographs if needed, and removing dietary triggers.

Do not start an exercise program. Do not allow pasture turnout. Do not aggressively reduce feed without guidance.

Laminitis management begins with stabilising the horse.

2. Remove High-Risk Feeds

For EMS or laminitis-prone horses, remove or strictly avoid:

• Sweet feed

• Grain mixes

• Molasses

• High-starch concentrates

• Sugary treats

• Large carrot or apple treats

• Unrestricted pasture

• Unknown hay for high-risk horses

• Feed room access

• “Conditioning” feeds unless low-NSC and appropriate

The feed bucket should become boring. Boring is good. Boring keeps hooves attached to the horse.

3. Test the Hay

For EMS horses, hay testing is one of the most important steps.

UC Davis recommends that hay for EMS horses ideally contain less than 10% NSC on a dry matter basis. The same source warns that hay appearance and type are not enough, because grass hay and alfalfa can both vary in carbohydrate content. (Center for Equine Health)

Do not assume:

• Grass hay is always safe

• Alfalfa is always unsafe

• Pale hay is low sugar

• Mature hay is automatically suitable

• Soaking guarantees safe NSC

Test it.

4. Feed Controlled Forage, Not Starvation

For most EMS horses, forage remains the foundation. The aim is controlled intake, not starvation.

UC Davis recommends that overweight EMS horses initially receive around 1.5% of ideal body weight in forage per day. This may be reduced to 1.25% after 30 days if needed, but sudden severe restriction should be avoided because it can worsen metabolic problems. (Center for Equine Health)

For a 1,000 lb horse, 1.5% of ideal body weight is about 15 lb of forage per day.

Use ideal body weight, not obese current body weight, when planning weight loss.

Weigh the hay. Flakes are not accurate.

5. Use a Ration Balancer or Mineral Supplement

A restricted hay diet may not provide enough vitamins, minerals, amino acids, salt, or vitamin E.

Many EMS horses do not need grain. They need:

• Low-NSC forage

• Salt

• Clean water

• A ration balancer or low-calorie mineral supplement

• Vitamin E where appropriate, especially if pasture is restricted

• Adequate protein and amino acids if topline is poor

UC Davis notes that horses on primarily hay-based diets should receive a ration balancer, and that mineral supplementation is especially important when hay is soaked because minerals can leach into the water. (Center for Equine Health)

The goal is to meet nutrition needs without adding unnecessary calories or insulin triggers.

6. Manage Pasture Carefully

Pasture is one of the biggest EMS traps.

Grass sugar levels can change by season, weather, time of day, stress, rainfall, frost, sunlight, and growth stage. UC Davis recommends reduced or eliminated pasture access for EMS horses, and Merck notes that the decision to allow grazing should depend on clinical signs, body condition, and post-meal insulin concentration. (Center for Equine Health)

For high-risk horses, the safest option is often:

• Dry lot turnout

• Track system with no meaningful grass

• Tested low-NSC hay

• Controlled hay feeding

• No unrestricted grazing

If pasture is allowed, consider:

• Grazing muzzle

• Very limited turnout

• Avoiding lush spring and autumn pasture

• Avoiding frosty or stressed grass

• Monitoring insulin response

• Checking feet daily

Time-based pasture restriction alone is unreliable. A horse can eat a lot of grass very quickly when given limited access, because apparently horses believe in speed-running poor decisions.

7. Use Exercise Only When the Horse Is Sound

Exercise can improve insulin sensitivity, increase calorie use, build muscle, and support weight loss.

But exercise is not appropriate during active laminitis.

UC Davis states that controlled and stable laminitis cases may benefit from walking if approved by a veterinarian, but exercise is not recommended for horses with active laminitis. Merck similarly notes that exercise helps insulin sensitivity after laminitis has resolved, but increasing exercise must not make the horse lame. (Center for Equine Health)

A good prevention plan may include exercise.

A painful laminitis case needs rest, pain control, foot support, and veterinary care.

8. Do Not Ignore Farriery

Hoof care is not optional in EMS horses.

Merck states that skilled farriery is essential in all EMS cases, even without obvious acute laminitis, and recommends regular hoof trimming by an experienced farrier in at-risk cases. It also notes that radiographs may be recommended to detect hoof distortion. (Merck Veterinary Manual)

A horse can have subclinical laminitis or hoof changes before the owner sees dramatic lameness.

EMS prevention is not just diet. It is diet plus feet.

9. Discuss Medication Only When Management Is Not Enough

Diet and management come first.

Some horses need additional medical support, especially those with persistent hyperinsulinemia, obesity that will not respond, or recurrent laminitis despite good management.

Options your vet may discuss include:

• Levothyroxine sodium for selected obese EMS horses to support weight loss

• Metformin in selected cases

• SGLT2 inhibitors in selected hyperinsulinemic or laminitis cases

• Pergolide if PPID is also present

Merck notes that no drug is currently labelled specifically for managing insulin dysregulation in horses, and that drugs should not be used without a proper diet. It also notes that EMS horses are not generally hypothyroid, although levothyroxine has been used short term to help with weight loss. (Merck Veterinary Manual)

Medication is not a shortcut around hay, pasture, weight, and hoof management.

Common Mistakes Owners Make

Waiting Until the Horse Is Very Lame

Mild foot soreness in an EMS horse matters. Do not wait for the dramatic rocked-back stance.

Trusting Hay Without Testing It

Hay can look safe and still be too high in NSC for a metabolic horse.

Using Pasture as “Natural” Feed

Pasture may be natural, but it can still be dangerous for insulin-dysregulated horses.

Starving the Horse

EMS horses need controlled calories, not crash dieting. Sudden severe restriction can worsen metabolic risk and create other problems.

Exercising During Active Laminitis

A painful laminitic horse should not be worked to lose weight.

Feeding “Low Sugar” Products Without Checking Labels

Marketing terms are not lab results. Check starch, sugar, NSC, calories, and feeding rate.

Relying on Supplements Instead of Management

Cinnamon, chromium, and magnesium are often marketed for insulin regulation, but Merck notes that these supplements have not been shown to improve insulin regulation in horses in experimental situations. (Merck Veterinary Manual)

How To Prevent Founder Long Term

Founder prevention in EMS is not a one-week plan. It is a long-term management system.

Focus on:

• Maintaining ideal body condition

• Monitoring neck crest and fat pads

• Testing insulin when risk signs appear

• Testing ACTH in older horses or PPID suspects

• Feeding tested low-NSC hay

• Weighing forage daily

• Avoiding grain, sweet feed, molasses, and sugary treats

• Restricting or eliminating pasture access

• Using a grazing muzzle only when appropriate

• Using a ration balancer instead of calorie-heavy feeds

• Providing salt and clean water

• Exercising only when sound

• Regular farrier care

• Radiographs when laminitis or hoof distortion is suspected

• Rechecking insulin and weight over time

• Adjusting the plan seasonally

UC Davis notes that EMS has no simple cure and that long-term care requires diligence, support, and veterinary guidance. (Center for Equine Health)

The best laminitis plan is boring, consistent, and slightly annoying to maintain.

That is exactly why it works.

Will My Horse Be Okay?

Many EMS horses do very well when the condition is recognised early and managed properly.

If the horse has no active laminitis, insulin can often improve with weight control, low-NSC forage, pasture restriction, exercise when sound, and careful monitoring.

If the horse already has laminitis or founder, the outcome depends on severity, pain control, coffin bone position, farriery, metabolic control, body weight, and how quickly treatment starts. Severe rotation or sinking carries a much more guarded prognosis. (Merck Veterinary Manual)

The key is early action.

A cresty neck is not cosmetic. Recurrent foot soreness is not normal. A fat pony that “lives on air” is not just cute. These are warning signs.

Catch EMS before the feet suffer.

FAQs

Can EMS in horses be cured?

EMS is usually managed rather than cured. Many horses improve significantly with weight control, low-NSC forage, pasture restriction, exercise when sound, and monitoring. Long-term management is usually needed.

What hay is best for horses with EMS?

The best hay is clean, mould-free, nutritionally appropriate, and tested low in NSC. UC Davis recommends hay ideally below 10% NSC on a dry matter basis for horses with EMS. (Center for Equine Health)

Should an EMS horse be on pasture?

Many EMS horses need pasture restricted or eliminated, especially during weight loss or after laminitis. Some may eventually tolerate limited muzzled turnout, but this should depend on body condition, laminitis history, and insulin response.

Can I exercise a horse with EMS?

Yes, if the horse is sound and not actively laminitic. Exercise can improve insulin sensitivity and weight control. Do not exercise a horse with active laminitis unless your vet has specifically cleared controlled movement. (Merck Veterinary Manual)

Is levothyroxine safe for EMS horses?

Levothyroxine may be used short term by veterinarians in selected obese EMS horses to support weight loss, but EMS horses are not usually hypothyroid. It should not be used as a substitute for diet, forage control, pasture restriction, and monitoring. (Merck Veterinary Manual)

Final Thoughts

Preventing founder in horses with EMS is about controlling risk before the feet fail.

The main pillars are clear: identify insulin dysregulation, test the hay, restrict NSC intake, control calories, manage pasture, support healthy weight loss, exercise only when sound, and protect the hooves with skilled farrier and veterinary care.

The mistake is waiting until the horse is dramatically lame.

The smarter approach is to act when the horse is still just cresty, overweight, pasture-sensitive, or mildly footsore. That is the window where prevention can change everything.

EMS management is not glamorous. It is measured hay, boring feed, restricted pasture, regular checks, and being the unpopular person who says no to the treat bucket.

That is not being mean.

That is protecting the horse from founder.

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If you are unsure whether your horse’s cresty neck, weight gain, pasture sensitivity, or foot soreness could be linked to EMS, ASK A VET™ can help you work through the warning signs and decide what needs veterinary attention before laminitis becomes a crisis.