Understanding Equine Metabolic Syndrome (EMS) and Laminitis: Essential Insights for Horse Owners

Equine Metabolic Syndrome Horse's-Typical Fat Deposit Areas

To understand the EMS horse who has laminitis flare ups, we must first understand the role of insulin.

Insulin is more than just a hormone. It is the gatekeeper of energy for your horse. When your horse eats, blood glucose levels rise and the pancreas releases insulin. Insulin allows glucose to move from the bloodstream into the cells where it can be used for energy, while keeping blood sugar within a normal range.

In horses with Equine Metabolic Syndrome, this process is disrupted. This is known as insulin dysregulation. When insulin can no longer do its job properly, glucose remains high in the bloodstream and insulin levels stay elevated. This sets off a cascade of problems throughout the body.

Over the last decade, EMS has become increasingly common in domestic horses. While there is no single cause, contributing factors are believed to include genetics, particularly within small breeding pools and pedigree lines, alongside modern management practices. These include man made packaged feeds and pasture grasses bred to be high yield and high sugar for dairy and beef production. All of these place a metabolic load on a system that was never designed to cope with constant energy abundance.

Although science has not yet given us a definitive answer as to why some horses develop EMS and others do not, what we do know is that when EMS manifests, the horse loses the ability to regulate insulin effectively. This malfunction significantly increases the risk of laminitis, a painful and potentially fatal disease of the feet.

Many EMS horses develop regional fat deposits. These are commonly seen along the crest of the neck, over the rump, tail head, shoulders, thighs, and sometimes as fat pads above the eyes. However, it is important to understand that EMS is not always a weight issue. Some horses with EMS may look lean or even underweight. This is why visual assessment alone is unreliable and blood testing is essential for diagnosis.

A common but often overlooked issue in EMS horses is the loss of normal satiety signals. Because insulin signalling is disrupted, these horses frequently do not feel satisfied by their food. They may appear constantly hungry, highly food driven, and prone to overeating when given the chance. At the same time, their metabolism is inefficient, making weight loss difficult and increasing frustration for both horse and owner.

Susceptible Breeds. Who is at Risk?

Certain breeds are more prone to EMS, particularly those often referred to as good doers. These include ponies, miniature horses, donkeys, cobs, and hardy feral-derived breeds such as Kaimanawas, Mustangs, and Brumbies. However, it is important to note that EMS can occur in any breed.

These hardy types evolved to survive on sparse vegetation, utilising glucose efficiently and maintaining body condition on limited resources such as scrub, tussock, and poor quality forage. When these horses are placed on rich pasture grasses, haylage, baleage, or high energy feeds, especially without sufficient movement, their metabolic systems can quickly become overwhelmed. This overload dramatically increases the risk of insulin dysregulation and laminitis.

The Dangers of Laminitis

Laminitis is one of the most serious and devastating consequences of EMS. It is an inflammatory condition of the sensitive laminae within the hoof, often triggered by elevated insulin levels rather than simple inflammation alone.

If not addressed early, laminitis can progress to what is commonly called founder. This occurs when the connection between the hoof wall and the coffin bone fails, allowing the bone to rotate or sink within the hoof capsule. This stage causes severe pain, long term lameness, and in some cases can be life ending.

EMS horses are particularly vulnerable. Even small changes such as a flush of new grass growth, a change in hay, or reduced movement can be enough to trigger a laminitic episode. These minor changes often catch owners off guard.

New Mediation Options:

In recent years, medications known as SGLT2 inhibitors, most commonly empagliflozin, have been used off-label in horses with severe insulin dysregulation and acute laminitis risk.

These drugs work at the level of the kidney. They block glucose reabsorption, forcing excess glucose to be excreted in the urine. As a result, blood glucose and insulin levels can drop rapidly, regardless of what the horse is eating.

In emergency situations, this can be life saving. Lowering dangerously high insulin levels quickly can reduce laminitis risk and help stabilise a horse during a metabolic crisis.

However, it is critical to understand what empagliflozin does and does not do.

Empagliflozin does not repair insulin sensitivity.It does not correct the underlying metabolic dysfunction.It does not address gut driven inflammation, forage mismatch, mineral imbalance, or chronic stress physiology.

It is a short term management override, not a cure.

There are real risks associated with its use, particularly if it is relied on without addressing the foundations. These include dehydration due to glucose pulling water into the urine, electrolyte imbalance, excessive or unsafe weight loss, and an increased risk of hyperlipidaemia, especially in ponies and donkeys. It can also mask dietary or management errors, giving a false sense of security while the underlying problem continues to progress.

Empagliflozin should only be used under veterinary guidance, with careful monitoring, a clear exit plan, and correct nutrition and management already in place. Used as a long term crutch, it can leave the horse metabolically fragile.

The Risk of Hyperlipaemia

Hyperlipaemia is another serious concern in EMS horses. When calorie intake drops too low, particularly during laminitis when movement is reduced, appetite may decrease, the body mobilises fat for energy. In EMS horses, this fat release can overwhelm the liver, leading to dangerously high fat levels in the blood.

This creates a vicious cycle where the horse eats less, releases more fat, and becomes increasingly unwell. This condition can progress rapidly and often requires urgent veterinary intervention.

Feeding soaked, low sugar hay ad lib through slow feeder haynets is a key strategy to reduce this risk while still controlling sugar intake.

Diagnosing EMS

EMS is diagnosed through blood testing, typically measuring insulin and glucose levels. Samples are usually taken in the morning before feeding to obtain the most accurate results. In some cases, dynamic testing may be recommended by your veterinarian.

A Path Forward

While EMS is a serious condition, it can be successfully managed. A forage first approach is essential. This includes careful grass management such as track grazing, feeding appropriate low sugar hay with non-structural carbohydrates ideally below ten percent, and avoiding processed feeds.

Regular movement suited to the horse’s soundness, combined with a well-balanced multi-mineral blend, supports metabolic health and insulin regulation. Supplements should support the system, not override it.

Working with people experienced in EMS and laminitis management can make a significant difference. Owners of EMS horses often feel overwhelmed, and support matters. You are not failing your horse by needing guidance.

Collaboration with an experienced veterinarian is also important for accurate diagnosis, appropriate medication use when necessary, and ongoing monitoring.

We hope this helps you better understand your EMS horse and the bigger picture behind insulin, laminitis, and metabolic health.

For a suitable laminitis recovery plan and EMS appropriate diet, please see this linkhttps://www.naturalhorse.co.nz/laminitis-recovery-info