Equine Metabolic Syndrome (EMS) = hormonal / metabolic disorder
Equine Metabolic Syndrome (EMS) is a hormonal and metabolic disorder that affects how an individual body processes food and stores fat. Think of it as a metabolic glitch, similar to Type 2 diabetes in humans where the body’s internal signalling gets confused.
Susceptible individuals – any can develop but it is most commonly seen in:
· Native ponies (Shetlands, Welsh, Connemaras, etc.)
· Cobs
· Draught horses
· "Good do-ers" (horses that seem to live on air and gain weight easily)
EMS Explained:
Characterised by insulin dysregulation, which significantly increases the risk of
1. The Insulin Glitch (Insulin Dysregulation)
Normally, when a horse eats, their body releases insulin to help absorb glucose (sugar) from the blood
In EMS horses: The tissues become less responsive to insulin (known as insulin resistance)
The reaction: To compensate, the horse’s pancreas produces massive, excessive amounts of insulin.
The danger: High levels of insulin circulating in the bloodstream (hyperinsulinaemia) directly damage the delicate laminae inside the hoof, triggering a painful laminitis flare up.
2. Weight & Regional Fat Pads
While many EMS horses are generally overweight, some can actually be at a healthy overall body weight but still suffer from abnormal insulin levels.
Instead of overall coverage, look for regional obesity, clumpy fat deposits that collect in specific areas:
· A thick, firm cresty neck
· Fat pads behind the shoulders
· A fleshy tailhead
- Fat around the sheath or udder
- Puffy areas above the eyes
- Laminitis
3. The Threat of Laminitis
For many owners, a sudden, unexplained bout of laminitis is the very first sign that something is wrong.
The Trigger: A flush of spring grass or feeds high in Non-Structural Carbohydrates (NSCs). NSCs are simply the easily digestible sugars and starches found in plants and grains. For an EMS horse, these sugars act like fuel on a fire.
The Golden Rule: Any case of recurrent, subtle, or unexplained laminitis should always raise immediate suspicion of underlying EMS.
Checklist: Should I Be Suspicious?
If you notice these subtle warning signs, it is time to call your vet for a simple blood test:
[ ] A firm, cresty neck that doesn't go away even if the individual loses weight
[ ] Unusual fat pads over the eyes, shoulder, or tailhead
[ ] An good do-er who struggles to lose weight despite a strict diet
[ ] Reduced exercise tolerance (seeming unusually sluggish or lazy)
[ ] A stronger or rapid digital pulse in the lower legs during minor flare ups
[ ] Unexplained foot soreness or mild, recurrent laminitis
The Confusion: EMS vs. PPID (Cushing’s Disease)
Because both conditions can cause laminitis, they are often confused, especially in older horses. However, they are completely different hormonal disorders.
EMS alone, they typically do not display these classic signs of PPID:
- A long, curly coat that is slow to shed out in summer
- Significant muscle wasting (particularly along the topline and hindquarters)
- Excessive drinking and urination (polydipsia and polyuria)
Summary: While both conditions can exist in the same horse (especially as they age), EMS is primarily a disease of nutritional storage and insulin control, whereas PPID is a degenerative brain to hormone disease of the pituitary gland.
How is EMS Diagnosed?
If you suspect EMS, it is time to get the vet out. They won't just guess, they will use a mix of physical checks and blood tests to get a clear picture.
Part 1: The Physical Exam (The Hands-On Check)
First, the vet will look at and feel the horse to assess their physical condition.
This includes:
- Body Condition Score (BCS): A rating scale (usually 1 to 9 or 1 to 5) to see how overweight the horse is overall. We will be putting together a BCS guide to help owners.
- Cresty Neck Score: A specific 0-to-5 rating scale just for the neck. The vet will feel how hard, thick, and inflexible the crest is. A score of 3 or more is a classic EMS warning sign.
- The History Lesson: The vet will ask about their weight history (do they gain weight just by looking at grass?) and whether they have ever had unexplained foot soreness or laminitis.
Part 2: The Blood Tests (The Science)
Vets use two main types of blood tests: resting tests and stress tests (dynamic tests).
1. Simple Blood Test (Resting Insulin & Glucose)
The vet takes a single blood sample while your horse is resting in their stable.
- What they measure: The amount of sugar (glucose) and insulin currently floating around.
- The catch: A horse with mild or early EMS can actually have a totally normal resting insulin level. If you only do this test, you might miss the diagnosis entirely!
2. The "Sugar Challenge" Test (Oral Sugar Test - OST)
Because resting tests can miss things, vets prefer to "challenge" the horse's system to see how it reacts in real time. This is called the Oral Sugar Test (OST).
- How it works: You (or the vet) give the horse a specific dose of sugary syrup by mouth.
- The test: The vet takes blood samples before and after the syrup.
- What it reveals: In a healthy horse, the body handles the sugar spike easily. In an EMS horse, the system panics and produces a massive, abnormal surge of insulin. It is highly sensitive and is the gold standard for catching EMS.
3. Specialist Hospital Tests (CGIT)
If the standard tests are inconclusive, a hospital setting might use a Combined Glucose Insulin Test (CGIT). This involves injecting glucose and insulin directly into a vein and taking multiple blood samples over several hours to see how quickly the body clears the sugar. It is highly accurate but usually reserved for tricky cases.
Dealing with EMS: Your Action Plan
Discovering EMS can feel overwhelming, but here is the good news:
EMS is highly manageable
While there is no "magic pill" cure, you have immense power to get them happy, healthy, and sound again.
Here is your step by step roadmap to managing EMS, starting with the most important step of all.
1. The Power of Weight Loss
If your horse is carrying extra weight, trimming down is the single most important thing you can do to lower their risk of laminitis.
- The Target: Aim for a safe, steady weight loss of 0.5% to 1% of their body weight per week. (For a 500kg cob, that’s about 2.5 to 5kg a week)
- How to get there: Cut back the calories, manage their pasture access, and get them moving (as long as they don't have active laminitis)
2. Smart Dieting (Keeping Sugars Low)
The main goal of an EMS diet is to prevent insulin spikes. You want to keep the total Non-Structural Carbohydrates (NSC), which is just sugar and starch, under 10% to 12% of their total diet.
3. Grazing & Grass Management
Grass is the trickiest part of managing EMS because grass sugars naturally fluctuate
Danger Hours: Grass sugars are highest on sunny afternoons and on bright, sunny mornings after a frosty night (the frost locks the sugar in the leaves)
To keep them safe while still letting them be a horse:
- Grazing Muzzles: A fantastic tool that allows turnout and movement while cutting grass intake by up to 80%
- Strip Grazing: Moving a fence line daily to limit how much fresh grass they can access
- Track Systems: Creating a "Paddock Paradise" loop around the edge of your field to encourage walking while restricting grazing access to the middle – pop a salt lick in one corner, water in another and some other amusements around the other corners to keep them active!
4. Get Moving! (The Natural Medicine)
If your horse is sound and has no active laminitis, exercise is like a superpower for EMS. Physical movement dramatically improves how responsive their cells are to insulin
- The Routine: Aim for 30 to 45 minutes of active exercise, 5 or more days a week
- The Workout: Brisk walking and trotting are perfect. Gradually build up their fitness as they lose weight
Note: Always get the green light from your vet before starting an exercise program if your horse has a history of laminitis
5. Veterinary Medication
Sometimes, diet and exercise need a helping hand, especially in the early stages or during a severe laminitis crisis.
- Your vet might prescribe a medication called Metformin
- How it helps: It temporarily helps control insulin levels. However, it isn't a permanent "get out of jail free" card, it works best alongside a strict diet and exercise plan, rather than replacing them
The Long Term Outlook: You've Got This!
It can feel like a lot of hard work, but the effort pays off. EMS is a lifelong commitment, but with the right routine:
- Many EMS individuals return to normal, active riding careers
- They can remain completely comfortable and sound
- You can successfully prevent future laminitis flare ups
By catching it early, taking control of the feed bucket, and keeping them active, you can give your horse a long, happy life.
Key Take Homes for Every Owner
- It’s hormonal, not just weight: EMS is a disorder of insulin control, not just a weight issue. Even lean horses can have EMS!
- Insulin is the culprit: High insulin levels are the direct trigger for EMS related laminitis.
- Management is medicine: Weight loss, a low sugar diet, and regular exercise are far more powerful than any miracle cure on the market.
- Test older horses for both: If you have an older or middle aged horse with recurrent laminitis, always ask your vet to test for both EMS and PPID (Cushing’s), as they often go hand in hand.
For individual advice, please contact nutrition@gbhorsepower.com
Final Thought:
The Diabetes Comparison: Similar, But Different
To make it easy to understand, Equine Metabolic Syndrome (EMS) is often compared to the early stages of Type 2 diabetes in humans, but there is a major difference.
In both humans and horses, the body’s tissues become stubborn and stop responding efficiently to insulin. To compensate, the body panics and pumps out massive, excessive amounts of it.
However, unlike humans with advanced diabetes, whose blood sugar levels skyrocket, horses with EMS are incredibly good at keeping their blood sugar levels perfectly normal.
In horses, the primary danger isn't high blood sugar, it is the high insulin itself. These dangerously high circulating insulin levels directly damage the hooves, acting as the main trigger for a painful bout of laminitis.
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