Understanding Equine Metabolic Syndrome (EMS)

A HØØF Knowledge Hub article

Equine Metabolic Syndrome (EMS) is a metabolic condition associated with insulin dysregulation and an increased risk of laminitis. The terminology can sound complicated, but the basic process is relatively simple to understand.

1. Start With Insulin

When a horse eats food containing sugars and starches, these are digested and glucose enters the bloodstream.

The body responds by releasing a hormone called insulin.

Insulin helps the body manage that glucose, including allowing tissues such as muscle to take glucose from the bloodstream and use or store it.

In a metabolically healthy horse, this system is carefully controlled.

Glucose rises → insulin is released → the body’s tissues respond → glucose is managed.

2. What Is Insulin Dysregulation?

In some horses and ponies, this system doesn’t work normally.

The term insulin dysregulation describes abnormalities in the way the body produces and responds to insulin.

This can include the body’s tissues becoming less sensitive to insulin — often called insulin resistance — and/or the horse producing an excessive insulin response after eating.

The result can be abnormally high concentrations of insulin in the blood, known as hyperinsulinaemia.

You don’t need to remember all of those terms.

The important point is:

The horse is no longer regulating insulin normally.

3. Why Does This Happen?

There isn’t one single cause.

Genetics can make some horses and ponies naturally more susceptible. Certain native and easy-keeping types appear particularly efficient at storing energy — an advantage when food is scarce, but potentially a disadvantage in modern management where energy-rich forage and feed can be readily available.

Body condition also matters.

Obesity and excess body fat can contribute to poorer insulin sensitivity, particularly in horses already predisposed to metabolic problems.

But EMS should not simply be thought of as “a disease of fat horses.”

A horse does not necessarily have EMS because it is overweight, and a horse with insulin dysregulation does not necessarily have to look obviously obese.

4. What Can Owners Actually See?

Some horses with EMS develop characteristic patterns of fat deposition.

These can include:

·       A cresty neck

·       Fat around the tailhead

·       Fat deposits around the shoulders or behind the eyes

·       Generalised obesity

·       Being an unusually “easy keeper”

·       Difficulty losing excess weight despite attempts to manage it

These signs don’t automatically mean a horse has EMS, but they can provide useful clues.

And there is another sign that matters enormously:

Unexplained or recurrent laminitis.

HØØF Top Tip

Don’t assume a horse has to be obviously fat to have insulin problems.

Body condition provides useful clues, but appearance alone cannot tell you whether a horse is regulating insulin normally.

If you are concerned about your horse’s metabolic health, particularly if there has been unexplained or recurrent laminitis, speak to your vet about appropriate investigation and testing.

5. Exercise and Insulin Sensitivity

Muscle is an important part of the body’s glucose and insulin system.

Regular, appropriate exercise can help improve insulin sensitivity — essentially helping the body’s tissues respond more effectively to insulin.

For a horse or pony at risk of EMS, maintaining suitable regular activity can therefore be an important part of metabolic management.

Inactivity, excess body fat, diet and genetic predisposition can all contribute to poorer insulin regulation.

This is important because exercise gives owners something they can potentially influence before laminitis occurs.

6. Then Laminitis Changes the Rules

Here lies one of the problems with EMS.

A horse with insulin dysregulation is at increased risk of developing endocrinopathic laminitis — laminitis associated with hormonal or metabolic disease.

Once laminitis develops, deliberately exercising the horse may be painful, inappropriate and potentially harmful.

Do not attempt to exercise a horse with suspected or active laminitis unless your vet has advised that it is appropriate.

This creates an unfortunate circle:

Poor insulin regulation → increased laminitis risk → laminitis develops → exercise becomes inappropriate → one useful way of improving insulin sensitivity is temporarily lost.

That is one reason prevention and early recognition matter so much.

7. Don’t Wait for Laminitis

If a horse is predisposed to EMS, there may be an opportunity to improve its management before its feet become painful.

Maintaining an appropriate body condition, managing dietary sugar and starch appropriately and providing suitable regular exercise can all form part of protecting metabolic health.

If your horse is an easy keeper, develops a cresty neck or abnormal fat deposits, struggles to lose excess weight, or you are otherwise concerned about its metabolic health, speak to your vet.

Testing can help establish whether insulin dysregulation is actually present rather than relying on appearance alone.

Identifying the problem early gives the horse’s vet/farrier team more options to manage it proactively.

Where increased exercise forms part of that management, your farrier also has an important role. Hoof balance, shoe choice and section, fit and the individual demands being placed on the foot can all be considered to help keep the horse comfortable as its workload changes.

8. What Has All This Got to Do With Laminitis?

For the hoof, this is the important connection.

Persistently or excessively high insulin concentrations can trigger changes within the foot that lead to laminitis.

The horse does not necessarily need to have eaten an enormous quantity of feed or escaped into the feed room.

The underlying problem may be the way its body is responding to what it eats.

That is why recurrent or apparently unexplained laminitis should never simply be dismissed as:

“He must have eaten something.”

There may be an underlying metabolic reason.

The Simple Version

The basic EMS pathway can be reduced to this:

Genetic predisposition + diet/body condition/activity → abnormal insulin regulation → excessively high insulin → increased risk of laminitis.

And the management principle is equally simple:

Recognise the risk → investigate it → manage diet and body condition → maintain appropriate exercise while the horse is sound → protect the feet.

HØØF Take-Home

You don’t need to understand every detail of glucose metabolism to understand EMS.

Remember insulin.

Insulin is normal and essential. The problem occurs when the horse no longer regulates it normally and insulin concentrations become excessive.

And don’t wait for laminitis before thinking about metabolic health.

Body condition, abnormal fat deposits, a cresty neck and difficulty managing weight can provide clues — but a horse doesn’t have to look obviously overweight to have insulin dysregulation.

Early recognition gives owners, vets and farriers more opportunities to act while appropriate exercise can still form part of the management plan.

Once laminitis develops, one of those valuable tools may temporarily disappear.

HØØF Knowledge Hub | HKH024

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