Equine Metabolic Syndrome in Horses: Cause, Symptoms and Treatment

Chubby horses have become a typical sight in our stables and pastures. It is not uncommon for overweight to affect robust breeds, ponies, small horses and cold-blooded horses. Too much weight on the ribs of our domestic horses is a serious matter, because the fat pads put a massive strain on the organism. The consequence can be a metabolic disease. We are talking about the Equine Metabolic Syndromein short EMS. EMS is a clinical syndrome that is associated with a complex of symptoms and in the worst of all cases results in laminitis.

Equine Metabolic Syndrome (EMS) - What is EMS?

Equine Metabolic Syndrome (EMS) is a metabolic disorder that primarily affects domestic horses. Interestingly, wild horses rarely suffer from EMS, as they must constantly roam vast, often barren landscapes in search of sparse vegetation. In contrast, our domesticated horses enjoy an abundance of lush pastures and nutrient-rich feed—far exceeding their natural needs.

After grazing on grass-rich paddocks, many horses are additionally provided with muesli, oats, or other concentrates, despite minimal physical workload. For many leisure horses, the term "work" is often a generous description of their actual level of exercise.

This imbalance—too much feed combined with too little exercise—gradually leads to overweight and the development of fat pads along the crest of the neck, above the eyes, and along the back. Apart from the obvious strain excess weight places on joints and bones, these localized fat deposits disrupt the horse's metabolism. Over time, this imbalance can progress into a full-blown equine metabolic disorder, characterized by insulin resistance, an increased risk of type II diabetes, and life-threatening laminitis.

One of the greatest challenges with EMS in horses is the vicious cycle it creates: metabolic dysfunction leads to weight gain, which in turn worsens metabolic issues. Breaking this cycle requires a comprehensive approach involving optimized management of feeding, exercise, and housing—a topic we will explore in detail later. But first, let’s take a closer look at how Equine Metabolic Syndrome develops in the first place.

What Causes Equine Metabolic Syndrome (EMS) in Horses?

In healthy horses, the body's sugar metabolism is well regulated. After feeding, blood glucose levels rise and are quickly brought back to normal by the hormone insulin, produced by the pancreas. If glucose drops too low, another hormone—glucagon—steps in to raise it again, ensuring stable energy availability.

However, in EMS horses, this metabolic regulation is disrupted. When horses consume high-energy feed such as rich pasture, grain, or muesli, blood glucose levels spike, prompting a strong insulin release. Insulin’s role is to transport glucose from the bloodstream into the body’s cells, where it is either used for energy or, if not needed, stored as fat.

Since many domesticated horses receive more energy than they expend—due to minimal exercise—the excess glucose is repeatedly converted into fat deposits, especially along the crest of the neck, above the eyes, and along the back. Unlike wild horses, which slowly digest small amounts of rough forage, these modern feeding patterns lead to sustained high blood glucose levels.

As a result, the pancreas produces increasing amounts of insulin to manage the surplus glucose. Over time, the horse's cells become insulin resistant, meaning they stop responding effectively to insulin. The body responds by releasing even more insulin—worsening the problem. This insulin resistance is a core feature of Equine Metabolic Syndrome.

Adding to the complexity, the fat pads common in EMS are not inert. These fat tissues actively release hormones involved in inflammation—including substances that stimulate the adrenal glands to release cortisol, a stress hormone. Cortisol further inhibits insulin, raising blood glucose even more and triggering a destructive cycle of metabolic dysfunction.

As fat cells multiply, they release more pro-inflammatory and toxic messenger substances. These not only impair insulin function but also damage liver function, disrupt immune defenses, and increase the risk of feeding-induced or hormonally triggered laminitis—one of the most dangerous complications of EMS in horses.

Because Equine Metabolic Syndrome develops gradually, it is often diagnosed late. Many of its symptoms overlap with other conditions, particularly Cushing’s disease (PPID). Misdiagnosis is a real danger—especially if EMS is mistaken for Cushing's and treated with cortisone, which can drastically worsen insulin resistance and lead to severe consequences.

To ensure the right treatment, veterinarians must carefully differentiate EMS from other disorders and investigate the root cause of unexplained fat accumulation and metabolic symptoms. A proper diagnosis is the first step toward restoring metabolic balance and preventing long-term damage.

EMS Symptoms in Horses: How to Recognize the Warning Signs

One of the most recognizable signs of Equine Metabolic Syndrome (EMS) is the accumulation of fat pads, particularly along the crest of the neck—often referred to as a “wobbly” or “cresty neck.” These fat deposits may extend along the spine, down to the base of the tail, and are more than just cosmetic. They are both symptom and cause of this serious metabolic disorder in horses.

Horses with EMS often score 7 or higher on the Body Condition Score (BCS) scale (which ranges from 1 to 9). At this point:

• The ribs are no longer palpable beneath the thick fat layer.
• A visible groove forms along the topline above the spine.
• In mares, a secondary fatty udder may develop.
• In geldings and stallions, fat accumulation around the sheath becomes evident.

But Equine Metabolic Syndrome manifests in more than just visible fat. There are numerous behavioral and physical symptoms to watch out for:

Common Signs of EMS in Horses

• Fat pads over the eyes, neck, shoulders, chest, sheath or udder, and tailhead
• Persistent hunger and food-seeking behavior (ravenous appetite)
• Muscle loss and a decline in performance
• Lethargy and reduced energy levels
• Stiffness in movement, sometimes resembling early signs of impaction or colic
• Circulatory issues and cold extremities
• Dull or patchy coat
• Heavy and rapid sweating, even with minimal exertion
• Frequent drinking (polydipsia) and urination (polyuria)
• Weakened immune system, leading to increased susceptibility to infections
• Chronic or creeping laminitis, often developing in intermittent, hard-to-detect episodes
• Fecal water or inconsistent manure
• Signs of type II diabetes
• Fertility issues in mares
• Lipomas (fatty tumors within the abdominal cavity), which may increase the risk of colic

If left untreated, the progression from EMS to laminitis is not just likely—it is often inevitable. Laminitis is one of the most severe outcomes of EMS and can result in permanent damage or euthanasia if not managed promptly.

The Hidden Danger: Leptin Resistance

Another key player in the EMS cycle is leptin, a hormone produced by fat tissue that normally suppresses appetite. However, horses with EMS often develop leptin resistance. Despite having abundant fat stores, their brains no longer respond properly to leptin signals, resulting in constant hunger and food-seeking behavior.

This means that even though the horse is overweight, it behaves as if it’s starving—leading to overeating, worsening fat accumulation, and further hormonal imbalance.

It’s easy to fall into the trap: a sweet apple here, a banana there, or a few treats after training. But for EMS-prone horses, this well-meant generosity can fuel a dangerous cycle of fat gain, metabolic disruption, and eventual collapse into chronic disease.

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

Accurate diagnosis of Equine Metabolic Syndrome (EMS) is critical for ensuring the long-term health and well-being of the horse. However, distinguishing EMS from Pituitary Pars Intermedia Dysfunction (PPID)—commonly known as Cushing’s disease—can be challenging, particularly in the early stages when many symptoms overlap.

Despite these similarities, Equine Metabolic Syndrome and Cushing’s disease are two distinct conditions with different underlying causes and treatment approaches. Recognizing the key differences is essential for effective management.

Key Differences Between EMS and Cushing’s Disease in Horses

📖 Must Read: Discover everything you need to know about this widespread metabolic disorder, its impact on horses, and the latest approaches to diagnosis and treatment.

While both conditions can lead to laminitis and require long-term management, it is crucial to correctly identify whether a horse is suffering from EMS or Cushing’s disease. Treatments differ significantly—what benefits one condition may worsen the other.

For example, administering corticosteroids to a horse with unrecognized EMS could significantly worsen insulin resistance, leading to rapid health deterioration.

Therefore, veterinarians should conduct a thorough clinical examination, detailed history evaluation, and appropriate laboratory testing to confirm the diagnosis and tailor the best management plan for the horse.

How is EMS Diagnosed in Horses?

Diagnosing Equine Metabolic Syndrome (EMS) can be particularly challenging, especially in the early stages. Many symptoms—such as loss of performance, muscle wasting, and a weakened immune system—can also indicate Cushing’s disease (PPID), infectious diseases, or other metabolic disorders. Therefore, a thorough clinical examination combined with targeted laboratory testing is essential to accurately identify EMS.

Step 1: Clinical Examination

Veterinarians first assess the horse’s body condition, looking for typical signs of EMS such as fat pads, persistent hunger, and signs of laminitis. However, since these symptoms can overlap with other diseases, a blood test is necessary for confirmation.

Step 2: Blood Testing for EMS

To diagnose EMS, veterinarians focus on two key indicators:

• Insulin levels in the blood
• Blood lipid (triglyceride) levels

The most common diagnostic methods include:

1. Fasting Insulin and Glucose Test
The horse must fast for at least six hours before testing to avoid food-related fluctuations. Blood samples are then analyzed for insulin and glucose concentrations. Elevated fasting insulin levels are a strong indicator of insulin resistance and therefore Equine Metabolic Syndrome.

2. Repeated Testing
Because stress, exercise, seasonal changes, or other illnesses can temporarily affect insulin levels, a second test is recommended within three weeks. Consistent findings are crucial to confirm a true EMS diagnosis rather than a false-positive result.

3. Combined Glucose-Insulin Test (cGIT)
This more complex test assesses how the horse’s body responds to a controlled sugar challenge. It provides a dynamic picture of glucose metabolism and insulin activity.

4. Oral Glucose Tolerance Test (OGT)
In the OGT, the horse is fasted overnight and then administered sugar water via a nasogastric tube the following morning. Blood insulin levels are measured two hours later.

• In healthy horses, the insulin level should remain below 68 mU/L.
• Elevated insulin readings indicate insulin resistance and support an EMS diagnosis.

Step 3: Ruling Out Cushing’s Disease

Especially in older horses, it’s vital to rule out Cushing’s disease (PPID). Therefore, the veterinarian often measures ACTH (Adrenocorticotropic Hormone) levels alongside insulin tests.

• A significantly elevated ACTH value suggests Cushing’s disease rather than pure EMS.

Accurate differentiation is critical because treatment strategies for EMS and Cushing’s disease differ substantially. Misdiagnosis could lead to inappropriate therapy, worsening the horse’s condition.

Key Principles for Treating EMS in Horses

A diagnosis of Equine Metabolic Syndrome (EMS) is not a life sentence for your horse. With the right approach, EMS in horses is treatable—but it requires commitment, consistency, and patience. There is no quick fix or miracle medication that simply melts away the pathological overweight associated with EMS.

The only sustainable way to break the vicious cycle of EMS is through targeted weight loss, achieved by combining adjusted feeding and regular exercise.

1. Controlled Feeding for EMS Horses

Reducing caloric intake is essential to manage EMS. Start by replacing high-sugar, high-starch feeds—like oats, corn, and molasses-based mueslis—with low-sugar, high-fiber forage, such as mature grass hay or late-cut timothy hay.

If your hay’s sugar content is unknown or borderline, consider soaking it in cold water for 30–60 minutes before feeding to reduce water-soluble carbohydrates. Avoid haylage or silage, which can be too energy-dense.

A practical example:
A 500 kg EMS-prone horse might only need 1.5% of its body weight in dry matter per day—that’s about 7.5 kg of soaked hay. Use a slow feeder hay net to extend eating time and reduce insulin spikes.

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 training plan, it’s crucial to assess whether the horse is also suffering from laminitis or other musculoskeletal conditions that could limit movement. Always consult with your veterinarian to define realistic goals and determine whether it's safe to begin a structured program—or if small steps should be taken first.

A training plan for horses with EMS must be individually tailored. Horses kept in active environments like open stables may already benefit from more movement during the day, whereas horses in box stalls or on limited turnout may need a more structured approach.

Regardless of housing, all EMS horses need a consistent training program. Endurance and conditioning work is key to burning fat, building muscle, and improving insulin sensitivity. Start by taking your horse on short walks across uneven or hilly terrain, which not only supports fitness but also improves coordination and balance.

Example:
Begin with 15-minute walks around the yard or on firm ground, then gradually increase the duration and add gentle trotting or hillwork over several weeks. Never jump straight into intense trail rides—build up slowly to avoid injury.

Feeding EMS Horses Correctly: What You Should Keep in Mind

Even the best training plan will fail if the feeding strategy is wrong. A starvation diet must be avoided—this can slow metabolism and increase the risk of liver problems. Instead, feed low-energy roughage, ideally late-cut hay mixed with up to one-third straw.

➡ 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.

EMS horses do not need concentrated feed like muesli, oats, or sweetened pellets. These only contribute to blood sugar spikes and worsen insulin resistance.

Which Mineral Feed for EMS Horses?

EMS horses still need balanced mineral nutrition to avoid deficiencies—especially when hay is soaked. Choose a low-sugar, low-starch mineral feed that compensates for any lost nutrients.

Pay special attention to manganese, a trace element that plays a central role in sugar metabolism. A deficiency in manganese can interfere with glucagon function, resulting in unstable blood sugar levels and food cravings.

Tip: Ask your vet or nutritionist for a trace mineral analysis if your horse shows signs of deficiency or sluggish weight loss.

Foods to Avoid if Your Horse Has EMS

Several feeds are strictly off-limits for horses with EMS:

• Fruits like apples and bananas
• Bread, molasses, and sugary treats
• Haylage or grass silage
• Flavored, preserved, or sweetened feeds

These products stress the liver, which is already burdened during fat breakdown and detoxification. A weakened liver increases the risk of laminitis.

Instead, support liver function with herbs such as milk thistle, birch leaves, nettle, and dandelion. These natural aids help the body manage toxin elimination more efficiently.

If turnout is still important for the horse’s mental health, consider using a muzzle to restrict grass intake while allowing social interaction.

Move, Move, Move: EMS Horse Training Tips

Movement is essential: it lowers blood sugar, reduces the need for insulin, and helps burn fat while building muscle mass. Even 20 minutes of walking can significantly improve insulin sensitivity.

But caution is key. Overtraining—especially in the anaerobic zone—can overload the detoxification organs and worsen metabolic strain. Training should increase step by step, based on the horse’s health status and hoof condition.

Guidelines based on hoof health:

• If laminitis is under control: Light work 4 days a week with or without rider weight. Try 30 minutes of brisk walking, some trotting, and light canter.
• If there is no laminitis: Exercise can increase to 5–6 days a week, including focused sessions on hindquarter activation, collection, and canter work, with or without a rider.

Always create feeding and training plans in close consultation with your veterinarian to ensure they align with the horse's current metabolic status.

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

Equine Metabolic Syndrome (EMS) is more than just a weight issue—it's a complex metabolic disorder with serious consequences for your horse’s health and quality of life. From insulin resistance to the risk of laminitis, EMS challenges us to rethink how we manage feeding, exercise, and day-to-day care.

The good news? EMS is treatable—especially when recognized early. With the right combination of:

• Targeted feeding strategies
• Regular, well-structured movement
• Veterinary guidance
• And owner commitment

…horses can lose weight, regain metabolic balance, and return to a stable, active life.

Remember: every horse is different. Whether you're caring for a Shetland pony or a heavy draft horse, the key to success lies in individualized planning and regular progress monitoring. What works for one horse may not suit another—so rely on your veterinarian and adjust accordingly.

EMS is manageable. But it takes 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.