Equine Metabolic Syndrome in Horses: Cause, Symptoms and Treatment

What is Equine Metabolic Syndrome?

What is EMS in horses—and why is it so dangerous?
Equine Metabolic Syndrome (EMS) is a serious metabolic disorder that primarily affects domesticated horses. It is characterized by a combination of insulin resistance, regional fat deposits, and a heightened risk of laminitis, a painful and potentially life-threatening inflammation of the hoof.

Unlike wild horses, which must constantly move through barren landscapes in search of scarce food, our domesticated horses often enjoy abundant feed—without needing to work for it. They graze on lush pastures and are frequently given muesli, oats or other high-energy concentrates. And yet, many of them receive little to no exercise.

This imbalance—too much feed, too little movement—leads to gradual weight gain. The excess fat accumulates in typical areas: along the neck crest, behind the shoulders, and above the eyes. These fat pads are not only a mechanical burden on the horse’s joints and hooves; they also interfere with the metabolic processes.

Over time, this metabolic disruption can result in insulin resistance in horses, resembling a form of equine diabetes. In the worst cases, it ends in laminitis, which causes intense pain and may permanently damage the hooves.

What Causes Equine Metabolic Syndrome (EMS) in Horses?

In a healthy horse, the metabolism keeps blood sugar levels in balance. After eating, blood glucose rises—and the hormone insulin, produced by the pancreas, brings it back to normal. If glucose drops too low, another hormone—glucagon—raises it again. This fine-tuned system ensures the horse always has enough energy.

But in horses with Equine Metabolic Syndrome (EMS), this balance is disrupted.

When your horse eats rich pasture, grain, or muesli, blood sugar levels spike. The pancreas reacts by releasing large amounts of insulin. This hormone’s job is to move glucose into the body’s cells—for energy or, if not needed, to be stored as fat.

The problem: Many leisure horses consume more energy than they burn. Without regular exercise, that excess energy is stored in typical locations—along the neck crest, over the eyes, or along the back. Over time, this leads to obesity and more fat deposits.

Unlike wild horses, who slowly chew on sparse forage, domesticated horses often experience constant sugar overload. Their pancreas tries to keep up—by producing more and more insulin. Eventually, the body’s cells become less responsive to it. This is called insulin resistance—a key symptom of EMS in horses.

But there’s more: the fat pads themselves aren’t just passive storage. They actively release inflammatory hormones, including those that trigger the release of cortisol, a stress hormone. Cortisol makes it even harder for insulin to work—creating a dangerous cycle of rising insulin levels and worsening metabolism.

As the fat tissue grows, it releases more of these damaging messengers. The consequences are severe:

• Impaired liver function
• Weakened immune system
• Increased risk of laminitis—especially after feeding or hormonal stress

Since EMS develops gradually, it often goes unnoticed for a long time. Many signs mimic other diseases—especially Cushing’s Disease (PPID). This overlap can lead to misdiagnosis, and if treated incorrectly (e.g. with cortisone), the insulin resistance may rapidly worsen.

That’s why an accurate diagnosis is essential. Only when the root cause is clear can treatment begin—and your horse get the chance to restore a healthy metabolic balance.

EMS Symptoms in Horses: How to Recognize the Warning Signs

How do you know if your horse has EMS?
The first red flag is often excess fat accumulation—especially along the crest of the neck. This so-called “cresty neck” feels soft and wobbly and may continue down the spine to the tailhead. These fat pads are not just cosmetic—they are both sign and cause of a deeper metabolic imbalance.

Horses affected by Equine Metabolic Syndrome (EMS) often have a Body Condition Score (BCS) of 7 or higher (on a 1–9 scale). Common signs include:

• Ribs are no longer palpable beneath thick fat layers
• A groove forms along the back
• Mares may develop fatty udders
• Geldings or stallions often show fat around the sheath

Common Signs of EMS in Horses

The following symptoms can indicate EMS in horses. Many appear gradually and may be mistaken for other conditions:

• Fat pads (neck crest, eyes, shoulders, chest, tailhead, sheath, udder)
• Persistent hunger despite being overweight
• Low energy and reduced performance
• Muscle loss or changes in topline shape
• Stiff movement, especially in cold weather or at rest
• Cold hooves or ears, suggesting poor circulation
• Dull or uneven coat
• Heavy sweating without effort
• Frequent urination and drinking (polyuria, polydipsia)
• Frequent infections or slow wound healing
• Recurring laminitis, even in mild, creeping episodes
• Fecal water or soft manure
• Signs of insulin resistance or type II diabetes in horses
• Reduced fertility (especially in mares)
• Internal fat tumors (lipomas)—raising colic risk

Untreated EMS almost always leads to laminitis—a devastating hoof condition that may cause permanent damage or result in euthanasia.

The Hidden Danger: Leptin Resistance

A lesser-known but crucial factor in EMS is leptin resistance.

Leptin is a hormone released by fat cells. It tells the brain: “You're full.” But in obese horses, the brain stops responding to leptin—so the horse continues to feel hungry even with large fat stores. The result: more eating, more fat storage, more disruption.

This miscommunication worsens the horse’s metabolic state, pushing it deeper into insulin resistance, increasing the risk of equine diabetes, and fuelling the spiral toward laminitis.

Even small treats—a carrot here, a banana there—can drive this cycle further. What feels like kindness can be harmful in EMS horses.

EMS and Cushing’s Disease in Horses: What Are the Differences?

Do EMS and Cushing’s Disease look the same? Sometimes, yes. But they’re not.
Equine Metabolic Syndrome (EMS) and Cushing’s Disease in horses—technically known as Pituitary Pars Intermedia Dysfunction (PPID)—share many symptoms. Both can cause laminitis, changes in body shape, lethargy, and coat abnormalities.

But despite these overlaps, they are two separate diseases—with different causes, risk groups, and treatments. Knowing the difference is crucial to avoid misdiagnosis and to manage your horse effectively.

Key Differences Between EMS and Cushing’s Disease

📖 Must Read: Learn how to spot the difference between insulin resistance in horses and hormone-related muscle loss. Accurate diagnosis can be the key to preventing laminitis and choosing the right treatment path.

How is EMS Diagnosed in Horses?

Diagnosing Equine Metabolic Syndrome (EMS) can be tricky—especially in the early stages. Many EMS symptoms—like muscle loss, infections, or laminitis—also appear in other diseases such as Cushing’s Disease (PPID) or general metabolic disorders.

That’s why accurate diagnosis requires a three-step approach: clinical observation, targeted lab tests, and differential diagnosis.

Step 1: Clinical Examination

Your vet will begin by assessing your horse’s body condition, behavior, and history. Key warning signs include:

• Distinct fat pads (neck crest, shoulders, tailhead)
• Excessive appetite and food-seeking behavior
• Signs of chronic laminitis

However, clinical signs alone are not enough—blood tests are necessary to confirm EMS.

Step 2: Blood Testing for EMS

Veterinarians usually test for:

• Insulin levels
• Glucose levels
• Triglycerides

The most common diagnostic methods include:

1. Fasting Insulin and Glucose Test
After 6–12 hours of fasting, blood samples are collected. Elevated insulin levels at rest strongly suggest insulin resistance in horses.

2. Repeat Testing
External factors like stress or weather can distort results. A second test after 2–3 weeks improves reliability.

3. Combined Glucose-Insulin Test (CGIT)
This dynamic test tracks the horse’s insulin response to an injected glucose challenge.

4. Oral Glucose Tolerance Test (OGT)
After fasting, the horse receives sugar water via a nasogastric tube. Two hours later, insulin levels should be < 68 mU/L. Higher values confirm insulin resistance.

Step 3: Ruling Out Cushing’s Disease

In horses over 15, EMS and PPID (Cushing’s) may overlap. A blood ACTH test helps differentiate.

• Elevated ACTH levels point to Cushing’s
• Normal ACTH + high insulin supports EMS

Correct diagnosis matters—because treatment plans differ sharply. For example, giving corticosteroids to an undiagnosed EMS horse can worsen insulin resistance and trigger laminitis.

Key Principles for Treating EMS in Horses

Good news: Equine Metabolic Syndrome is manageable—but it takes a clear plan and consistency.

There is no quick fix. No pill can melt fat or normalize insulin levels overnight. But with the right strategy, your horse can return to metabolic balance.

1. Controlled Feeding for EMS Horses

Caloric reduction is essential. Start by eliminating:

• Oats, barley, corn
• Molasses-based mueslis
• Sugary treats or fruits

Instead, feed:

• Low-sugar forage like late-cut timothy or mature meadow hay
• 1.5% of body weight in dry matter per day (e.g. ~7.5 kg hay for a 500 kg horse)

2. Structured Exercise Program for EMS Horses

Regular, moderate-intensity movement is one of the most effective ways to improve insulin sensitivity and burn excess fat. But EMS horses often have reduced stamina or early-stage laminitis, so start cautiously.

Begin with hand-walking or walking under saddle for 15–20 minutes, 5 days a week. Gradually add trot intervals on soft footing or pole work to stimulate muscle development and balance.

Example weekly progression:

• Week 1–2: 20 minutes walk in-hand
• Week 3–4: Add 5 minutes trot in short bursts
• Week 5+: Include light groundwork or hill walking

3. Weight Loss and Progress Monitoring

Start with a realistic goal: losing 0.5–1% of body weight per week is healthy and sustainable. Use a Body Condition Score (BCS) chart and aim to bring the horse to a score of 5/9.

Track progress by:

• Measuring girth circumference weekly
• Using a weight tape in the same spot every time
• Taking monthly photos from front, side, and rear angles

Example: A gelding starts at 600 kg and needs to reach 520–540 kg. Track trends, not daily fluctuations. If progress stalls, slightly reduce caloric intake or increase duration of exercise.

📋 Keep a simple logbook or app to record measurements and adjust accordingly.

4. Consider the Horse’s Regeneration Needs

EMS horses are not just overweight—they may also suffer from subclinical laminitis, fatigue, or reduced circulation. Pushing too hard can worsen their condition.

Give your horse rest days between training sessions and ensure daily turnout in a safe, dry paddock. Avoid deep mud or rocky terrain that stresses the feet. Ensure your farrier understands laminitis management and keeps the hooves balanced.

Recovery example:
If your EMS horse shows signs of soreness after trotting, scale back to walking-only sessions and consider using hoof boots for extra comfort.

Lose Weight Properly: Training Plans for EMS Horses

Before starting any exercise routine, make sure your horse is fit to move. Consult your veterinarian to rule out laminitis or orthopedic issues that might limit activity. Only then can you define realistic goals and decide whether to begin with structured exercise—or with small, gentle steps.

A successful EMS training plan must be tailored to each individual horse. Horses kept in active environments, such as open stables, may already benefit from passive movement. In contrast, stall-kept horses need structured and consistent support.

What matters most? Regularity.
Movement burns fat, builds muscle, and enhances insulin sensitivity in horses—a key to reversing EMS.

Start small:

Begin with short 15-minute walks on firm or slightly uneven ground. Over time, gradually increase duration and intensity by adding light trotting or hillwork.

⚠️ Don’t rush: sudden trail rides or intense sessions can cause injury and stress. Progress slowly.

Feeding EMS Horses Correctly: What You Should Keep in Mind

Even the best training fails without the right diet. But beware: starving your horse is not the answer. Too little energy can slow metabolism and increase the risk of fatty liver.

➡ Must Watch: Learn why low-energy forage, the right hay-straw ratio, and soaking hay are essential feeding strategies to support your horse’s health with EMS.

Instead, focus on:

• Late-cut hay or mature grass hay
• Mixed with up to 30% straw
• No haylage, sweet feeds, or energy-dense silage

If you're unsure of the sugar content in your hay, soak it in cold water for 30–60 minutes. This reduces water-soluble carbohydrates (WSCs) and makes the forage safer for EMS horses. Feeding soaked hay via a slow feeder net helps stretch eating time and avoid insulin spikes.

Which Mineral Feed for EMS Horses?

EMS horses still need a balanced mineral supply—especially when hay is soaked, as it may lose key nutrients. Choose:

• Low-sugar, low-starch mineral supplements
• Enriched with trace elements critical to sugar metabolism

⚠️ Pay attention to manganese, a mineral essential for glucagon regulation. Without it, blood sugar becomes unstable, and hunger may increase.

💬 Pro tip: Ask your vet for a mineral analysis if your horse shows persistent metabolic symptoms despite dietary control.

Foods to Avoid if Your Horse Has EMS

Strictly avoid these feeds—they can spike blood sugar and worsen insulin resistance:

• Fruits (e.g., apples, bananas)
• Bread, molasses, sugary treats
• Haylage or grass silage
• Flavored, sweetened, or preserved feed mixes

These items also burden the liver, which is already strained during fat metabolism. Support detox with herbs like:

• Milk thistle
• Dandelion
• Nettle
• Birch leaves

Still want your horse to enjoy pasture time? Use a grazing muzzle to limit grass intake while allowing social interaction.

Move, Move, Move: EMS Horse Training Tips

Movement is medicine for EMS. It lowers blood sugar, increases insulin sensitivity, and supports fat reduction.

Even 20 minutes of walking per day makes a difference. But don’t overdo it: intense or anaerobic training may strain the detox organs and worsen the metabolic load.

Guidelines based on hoof condition:

• ✅ If laminitis is stable: Start with light work 4 days per week. Include walking, short trots, and gentle canters—with or without a rider.
• ✅ If no laminitis is present: Increase to 5–6 days per week. Focus on activating hindquarters, transitions, and balanced canter work.

🚨 Always align your feeding and training plans with your veterinarian to ensure safety and metabolic suitability.

Final Thoughts: Managing EMS Requires Awareness, Action, and Consistency

EMS in horses is not just about being overweight. It’s a complex metabolic disease with serious consequences—from insulin resistance to laminitis.

But here’s the good news: it’s treatable. Early detection, smart feeding, and regular movement—supported by veterinary guidance—can lead your horse back to metabolic health.

With:

• Targeted nutrition
• Consistent exercise
• Professional supervision
• And your commitment…

Your horse can lose weight, regain vitality, and return to a stable, active life.

Remember: every horse is different. Tailor your plan, monitor progress, and stay flexible. EMS is manageable—but only with awareness, action, and above all: consistency.

FAQs: Frequently Asked Questions about EMS in Horses

How can you recognize EMS in horses?

‍EMS is typically identified by fat deposits along the crest of the neck, at the tailhead, and above the eyes, combined with excess body weight and a tendency to develop laminitis.

Which treats are suitable for EMS horses?

‍EMS horses can occasionally receive low-sugar treats, such as small amounts of carrots, unsweetened vegetables, or special EMS horse treats formulated without sugar or starch.

What should an EMS horse not eat?

‍Avoid giving EMS horses sweet snacks like apples, bananas, bread, or grass silage. These foods are high in sugar and starch and can negatively impact their metabolism.

How should you feed a horse with EMS?

‍EMS horses should be fed soaked hay, lean roughage, and low-sugar mineral feed. Concentrated feeds are usually unnecessary and may worsen the condition.

How is EMS treated in horses?

‍The treatment includes a combination of adjusted feeding, regular exercise, and, in some cases, medications that help improve insulin sensitivity.

How long can an EMS horse graze?

‍EMS horses should only graze in a limited and controlled manner, ideally on low-fructan pasture and with a grazing muzzle to restrict grass intake.

Which supplements are beneficial for EMS horses?

‍Useful supplements include low-sugar mineral feeds and herbs like milk thistle, nettle, and dandelion, which support liver function and metabolism.

Is EMS hereditary in horses?

‍Yes, EMS has a genetic component and is especially common in easy keeper breeds like ponies, draft horses, and cold-blooded types. Genetics can influence the likelihood of developing EMS.

Can exercise improve EMS in horses?

‍Absolutely. Regular exercise enhances insulin sensitivity, promotes weight loss, and supports overall metabolic health in horses with EMS.

What causes EMS in horses?

‍EMS develops due to a combination of genetic predisposition, overfeeding, and lack of exercise, leading to obesity and insulin resistance.