Introduction: Understanding Founder and Equine Metabolic Syndrome 🧬

Founder, or laminitis, is a serious and painful hoof condition that affects a large number of horses each year. It’s often seen in horses that are overweight or have equine metabolic syndrome (EMS)—a condition that was once misunderstood but is now known to be linked to insulin resistance. In this guide, Dr Duncan Houston outlines the steps you can take in 2025 to prevent founder, manage insulin levels, and keep your horse healthy with a diet tailored to EMS.

1. What Is Equine Metabolic Syndrome (EMS)? 🐎⚠️

Equine metabolic syndrome is a disorder characterized by insulin resistance, regional fat deposits, and a predisposition to laminitis. Horses with EMS are often called "easy keepers" because they gain and maintain weight on minimal feed. Now we know why—these horses have difficulty using insulin effectively, leading to chronically high insulin levels, which is directly linked to founder.

• 📈 Insulin resistance: The body doesn’t respond properly to insulin, prompting the pancreas to release even more.
• 🔥 High insulin = laminitis: Elevated insulin levels damage the lamellae in the hoof, triggering inflammation and founder.
• 🧪 Testable condition: Bloodwork can measure insulin to identify horses at risk for founder due to EMS.

2. How Founder Happens—and Why It’s So Serious 💥

Founder (laminitis) occurs when the lamellae—the connective tissues inside the hoof—become inflamed or damaged. This causes extreme pain and can lead to permanent lameness or even require euthanasia in severe cases. Common signs of laminitis include:

• 🚶‍♂️ Reluctance to move
• 🧊 Hoof heat and strong digital pulse
• 📏 Short, careful strides or rocking back on heels
• 😣 Visible distress or pain

Preventing founder begins with managing insulin resistance—and that starts with the diet.

3. Diet Strategy: Feed Low-Carbohydrate Hay 🍃

The first step in EMS management is reducing non-structural carbohydrates (NSC) in the diet. NSCs include sugars and starches, which rapidly elevate insulin. Here's what Dr Duncan Houston recommends:

• 📏 15 lbs of hay per day: For a 1,000 lb horse (1.5% body weight), ideally split into multiple feedings.
• 🧪 Test your hay: Hay should contain less than 10% NSC. Testing is the only way to know for sure.
• 💧 Soak hay to reduce sugar: Soaking hay in water can reduce carbohydrate content—but test again after soaking to ensure it’s below 10% NSC.

Uncontrolled access to high-sugar hay or pasture can rapidly trigger laminitis in EMS horses, even in small quantities.

4. What to Supplement: Vitamin E & Low-Carb Feed 💊

To ensure balanced nutrition without triggering insulin spikes, EMS horses should receive:

• 🧴 Vitamin/mineral supplement with vitamin E: Many EMS horses on hay-only diets are deficient in vitamin E, which supports immune and nerve function.
• 🥣 Low-carb grain: Only use specially formulated feeds designed for metabolic horses—avoid sweet feeds or typical performance rations.

Consult with your vet to choose a feed or balancer that fits your horse’s individual needs without contributing to insulin surges.

5. Manage Pasture Carefully—or Eliminate It 🚫🌾

Pasture grass is the leading source of NSC in most horses’ diets—especially during spring or after rainfall when grass is lush. For EMS horses, pasture time must be restricted or eliminated:

• 🧱 Dry lot housing: A dirt paddock with no grass is safest for EMS horses.
• 😷 Grazing muzzles: If turnout is allowed, use a muzzle to reduce intake by 50–80%.
• ⏳ Time-based restriction: Avoid turnout during the afternoon when NSC levels peak in grass.

Even short access to pasture can trigger laminitis in insulin-resistant horses. Monitor carefully and prioritize forage with known, tested NSC values.

6. Weight Loss and Thyroid Support 🧠⚖️

Because weight loss takes time—and insulin resistance persists until weight is reduced—some horses may benefit from thyroid support to jumpstart their metabolism:

• 🩺 Levothyroxine sodium: This thyroid supplement can increase insulin sensitivity and aid in safe weight loss.
• 📉 Target slow, steady loss: Aim for 1–2% of body weight per month.
• 🏃 Exercise, if sound: Low-intensity exercise enhances insulin sensitivity—but must be postponed if founder is already present.

Talk to your veterinarian about thyroid function tests and whether this medication is appropriate for your horse's EMS management plan.

7. Testing & Monitoring: The Cornerstones of Prevention 🧪🩺

Effective founder prevention relies on regular monitoring:

• 🧫 Test insulin levels: Elevated fasting insulin confirms metabolic syndrome and indicates risk.
• 📊 Track body condition score (BCS): Target a BCS of 5/9—neither too fat nor too thin.
• 🔁 Re-test hay sources each season: NSC levels vary between hay types, cuts, and even storage conditions.

8. Final Advice from Dr Duncan Houston 🐴❤️

• 🍃 Hay is the foundation: Use tested, low-NSC hay as your primary feed.
• 🚫 Restrict sugar & starch: Avoid treats, sweet feeds, and lush pasture.
• 🩺 Monitor insulin and BCS: Keep detailed records and adjust as needed.
• 💡 Stay proactive: EMS and laminitis are preventable with the right plan.

Need Help Managing Equine Metabolic Syndrome? Ask A Vet 📲

Preventing founder is possible—with the right support. Download the Ask A Vet app to connect with Dr Duncan Houston and other veterinary experts. Get personalized diet plans, hay testing guidance, and 24/7 support to keep your horse founder-free and thriving. 🐴💚