What Are the Early Signs of EMS in Horses? What Owners Should Look For
- Dr Silver
- Aug 9
- 11 min read
Equine Metabolic Syndrome (EMS) is often associated with the stereotypical “good-doer” horse: easy to keep weight on, carrying a cresty neck and prone to laminitis.
But that picture is incomplete.
A horse does not have to look obviously overweight to have insulin dysregulation, and a cresty neck does not by itself diagnose EMS.
The central feature of EMS is insulin dysregulation (ID). Excess body fat, particularly abnormal regional fat deposits, is commonly associated with EMS, but the relationship is not absolute. Veterinary consensus guidance emphasises that EMS is a collection of risk factors for endocrinopathic laminitis rather than simply a condition defined by obesity.
This makes recognising possible early warning signs important — but it also means owners need to look beyond appearance.
Important: This article provides general educational information and is not a diagnosis. If you are concerned that your horse may have EMS, insulin dysregulation or laminitis, speak to your veterinary surgeon.
What Is EMS in Horses?
Equine Metabolic Syndrome is primarily characterised by insulin dysregulation, together with risk factors such as obesity or abnormal fat distribution and an increased risk of endocrinopathic laminitis.
Insulin dysregulation is a broad term covering abnormalities in the normal relationship between insulin, glucose and other aspects of metabolism.
It can include:
Abnormally high resting insulin
An excessive insulin response to carbohydrate
A prolonged insulin response after carbohydrate intake
Tissue insulin resistance
Other disturbances of glucose and lipid metabolism
Importantly, insulin dysregulation is not synonymous with simply having a high body condition score.
The major reason EMS matters is its relationship with endocrinopathic laminitis.
What Are the Early Signs of EMS?
There is no single physical sign that confirms EMS.
Instead, owners may notice a combination of body-condition changes, regional fat deposition, weight-management difficulties and a history of laminitis.
Some horses may show several clues. Others may show very little outwardly.
Here are the main things worth monitoring.
1. A Pronounced or Increasing Neck Crest
A prominent neck crest is one of the features commonly associated with regional adiposity in metabolically at-risk horses.
Research has also found that cresty-neck scoring can provide useful information about insulin dysregulation in ponies.
However, this needs an important qualification:
A cresty neck is not a diagnosis of EMS.
Breed, conformation, age, body condition and individual fat distribution all influence how a horse's neck looks.
It is more useful to monitor changes over time and consider the neck alongside the rest of the horse.
2. Abnormal Fat Distribution
EMS-associated obesity is not necessarily evenly distributed.
Some horses develop noticeable fat deposits in particular areas, including:
The crest of the neck
Around the tail head
Behind the shoulders
Over the hindquarters
Other regional fat stores
The presence of regional adiposity can increase suspicion of metabolic dysfunction, but it does not prove that insulin dysregulation is present.
In fact, the ECEIM consensus statement makes an important distinction:
A horse can have excessive fat deposits without having insulin dysregulation, and insulin dysregulation can occur in a horse without obvious obesity.
That is why body condition should be considered a piece of the puzzle, not the whole diagnosis.
3. Weight Gain That Happens Easily
Some horses seem to maintain or gain bodyweight very easily, particularly when pasture availability increases.
These horses are often described by owners as:
“Good doers”
“Easy keepers”
“Easy to feed”
This phenotype can be associated with metabolic risk, particularly when excess body fat develops.
But there is an important distinction between being an easy keeper and having EMS.
A horse can be an easy keeper simply because its energy intake exceeds its requirements.
Therefore, easy weight gain should be treated as a reason to pay attention to body condition and metabolic risk — not as proof of insulin dysregulation.
4. Difficulty Losing Excess Weight
Another useful warning sign is a horse that remains overweight despite a carefully managed weight-loss programme.
The ECEIM consensus recognises a predisposition to weight gain and resistance to weight loss as features associated with obesity in the EMS context.
However, weight loss depends on many factors, including:
Total calorie intake
Forage energy density
Pasture access
Concentrate feeding
Treats
Exercise
Bodyweight
Individual metabolism
If a horse is not losing weight as expected, the answer is not necessarily “it must have EMS”.
The diet and management programme should first be assessed objectively, and veterinary advice may be appropriate.
5. Previous or Recurrent Laminitis
This is one of the most important reasons to consider metabolic health.
Insulin dysregulation is a major risk factor for endocrinopathic laminitis, and EMS is one of the conditions associated with this risk.
A horse with recurrent or unexplained laminitis should therefore be assessed for possible endocrine causes.
This is particularly important when laminitis occurs in a horse that also has:
Excess body condition
Regional fat deposits
Easy weight gain
A previous history of metabolic problems
However:
Laminitis does not automatically mean EMS.
Laminitis has multiple possible causes, so identifying the underlying cause is important.
6. Subtle Changes in Comfort or Movement
Owners of horses at metabolic risk should become familiar with their horse's normal movement.
Changes such as:
Shorter steps
Reluctance to turn
Stiff movement
Increased sensitivity on hard ground
Reluctance to move
A change in stance
can potentially be important if laminitis is developing.
These signs are not specific to EMS, but they should never be dismissed in a horse at risk of endocrinopathic laminitis.
If you suspect laminitis, contact your veterinary surgeon rather than waiting to see whether the signs disappear.
7. Changes in Drinking or Urination
Changes in thirst or urination can occur with a range of medical conditions.
They are therefore not specific signs of EMS.
If your horse suddenly begins drinking substantially more, urinating more frequently or producing unusually large volumes of urine, veterinary investigation is sensible.
It is better to investigate the underlying cause than to assume that a metabolic supplement will address the problem.
8. Reduced Energy or Changes in Behaviour
Some metabolically affected horses may appear less energetic, but this is a very non-specific observation.
Reduced energy can result from:
Pain
Poor fitness
Musculoskeletal problems
Infection
Dental problems
Nutritional imbalance
Respiratory disease
Metabolic disease
Many other causes
Therefore, lethargy should not be presented as a diagnostic sign of EMS.
Instead, a noticeable change in normal behaviour or energy should prompt a broader health assessment.
9. Metabolic Risk Despite a Normal-Looking Bodyweight
This is perhaps the most important misconception to challenge.
A horse can have insulin dysregulation without looking obviously overweight.
The ECEIM consensus specifically notes that adiposity is not inseparably linked with insulin dysregulation and that EMS can occur with a lean phenotype.
This means:
“My horse isn't fat, so it can't have EMS” is not a scientifically reliable assumption.
Conversely, an overweight horse does not automatically have EMS.
Both statements matter.
Body condition can help identify risk, but insulin regulation needs to be assessed separately when there is sufficient clinical suspicion.
10. A Combination of Risk Factors
Often the strongest reason to investigate EMS is not one isolated sign but a pattern.
For example, a horse may be:
An easy keeper
Carrying a pronounced neck crest
Developing regional fat deposits
Struggling to lose weight
Previously affected by laminitis
Receiving a high-calorie diet
Spending substantial time on rich pasture
One factor does not establish EMS.
But several factors together may justify discussing metabolic testing with your veterinary surgeon.
Can a Horse Have EMS Without Being Overweight?
Yes.
This is an important point because EMS is often simplified into “overweight horse + cresty neck”.
The veterinary literature does not support such a simple definition.
The ECEIM consensus states that EMS can occur in association with a lean phenotype and that excessive fat deposits can also occur without concurrent insulin dysregulation.
In other words:
Fat does not equal EMS.
And:
Being lean does not rule out insulin dysregulation.
This is one reason why metabolic assessment should be based on the whole clinical picture.
Does a Cresty Neck Mean a Horse Has EMS?
Not necessarily.
A cresty neck is a useful risk indicator, particularly when it is pronounced or increasing, and research has demonstrated an association between cresty-neck scoring and insulin dysregulation in ponies.
But it is not a standalone diagnostic test.
A horse can have a prominent neck without having EMS.
And a horse can have insulin dysregulation without an obvious cresty neck.
Think of the crest as one piece of evidence, not the answer.
How Is EMS Diagnosed?
EMS cannot be reliably diagnosed from photographs, body condition or a cresty neck alone.
Veterinary assessment may consider:
Previous laminitis
Body condition
Regional fat distribution
Diet
Exercise
Pasture access
Age
Breed and individual risk
Resting insulin
Dynamic insulin testing
Other relevant laboratory findings
The ECEIM consensus recommends laboratory assessment of insulin dysregulation alongside the clinical history and examination.
Testing needs to be interpreted carefully because the result can depend on the specific test, assay, feeding conditions and other factors.
This is particularly important when owners see a single insulin result online and try to interpret it without considering how the sample was obtained.
What Is Insulin Dysregulation?
Insulin dysregulation describes abnormalities in the way insulin and glucose are regulated.
It can include:
Hyperinsulinaemia
Abnormally high circulating insulin.
Insulin resistance
Reduced responsiveness of tissues to insulin.
Excessive insulin response
An exaggerated insulin response following carbohydrate intake.
These abnormalities can overlap.
The relationship between insulin dysregulation and laminitis is one of the key reasons metabolic health matters in horses.
Why Does Insulin Dysregulation Matter?
The biggest concern is the increased risk of endocrinopathic laminitis.
Research has demonstrated a strong relationship between prolonged hyperinsulinaemia and lamellar damage, while the ECEIM consensus identifies insulin dysregulation as the most important risk factor for endocrinopathic laminitis.
This is why managing an insulin-dysregulated horse is not simply about making the horse look slimmer.
The goal is to reduce metabolic risk and improve insulin regulation while maintaining adequate nutrition.
What Should You Do If You Suspect EMS?
Don't start by adding lots of supplements.
Start by looking at the fundamentals.
1. Assess body condition
Look at the whole horse rather than concentrating exclusively on the neck.
2. Review the complete diet
Consider everything the horse consumes:
Hay or haylage
Grass
Concentrates
Treats
Supplements
Balancers
Additional feeds
3. Consider forage analysis
Forage can contribute a substantial proportion of a horse's daily sugar, starch and calorie intake.
Testing the forage can therefore provide useful information when designing a controlled diet.
4. Review pasture access
Pasture intake can vary substantially with season, weather, grass growth and individual grazing behaviour.
Do not assume that a horse's pasture exposure is insignificant simply because no bucket feed is being provided.
5. Monitor bodyweight
Regular measurements can reveal whether management is actually producing the intended change.
6. Monitor for laminitis
Know your horse's normal gait and comfort.
A change should be investigated promptly.
7. Speak to your veterinary surgeon
If there is a genuine concern about insulin dysregulation, veterinary testing can provide information that appearance alone cannot.
What About Sugar and Starch?
This is where EMS management becomes more nuanced than simply saying “avoid sugar.”
Sugar and starch are components of the broader group of non-structural carbohydrates (NSC), although terminology and measurement methods matter.
The objective is not to create a nutritionally inadequate diet.
Instead, the diet should provide appropriate energy and essential nutrients while controlling the sources and amounts of rapidly digestible carbohydrate that are relevant to the individual horse.
And there is an important point that owners sometimes miss:
There is no single NSC percentage that guarantees that every horse will have a normal insulin response.
Individual horses can respond differently to carbohydrate intake.
This is one reason why diet should be individualised rather than based on a single number printed on a feed bag.
For a detailed discussion of forage, calories, NSC and feeding strategy, see our guide:
Best Diet for a Horse With EMS
Can Exercise Help a Horse With EMS?
Appropriate exercise can form an important part of metabolic management.
The ECEIM consensus identifies dietary strategies and exercise programmes as the mainstays of EMS management, with the aim of improving insulin regulation and reducing obesity where present.
However, exercise needs to be appropriate for the individual horse.
Do not exercise a horse that is showing signs of active laminitis unless your veterinary surgeon specifically advises you to do so.
For a sound horse, exercise can be considered as part of a structured weight-management and metabolic-health programme.
Can Supplements Help a Horse With EMS?
A supplement should be viewed as one component of nutritional management, not as a treatment for EMS.
No supplement can compensate for:
Excess calorie intake
Uncontrolled pasture access
Excess body condition
Inappropriate feeding
Insufficient exercise where exercise is appropriate
Failure to address an underlying endocrine disorder
The fundamentals come first.
Where a horse's diet has already been appropriately formulated, a complementary feed may be used to provide specific nutritional support.
Dr Silver EMS & Insulin Support PRO is formulated as a complementary feed for horses and ponies requiring nutritional support as part of a controlled diet.
It is not a veterinary medicine and is not intended to diagnose, treat or cure EMS.
EMS Is About More Than Bodyweight
One of the most useful ways to think about EMS is to separate three things:
Body condition
What does the horse look like?
Metabolic function
How is the horse regulating insulin and glucose?
Clinical history
Has the horse experienced laminitis or other relevant problems?
These three areas overlap, but they are not interchangeable.
An overweight horse may not have insulin dysregulation.
A lean horse may have insulin dysregulation.
And a horse with insulin dysregulation may look outwardly quite normal.
That is why testing and clinical assessment matter.
Early EMS Signs: A Practical Owner Checklist
If you're concerned about your horse's metabolic health, ask yourself:
☐ Has my horse gained weight easily?
☐ Is my horse difficult to slim down?
☐ Has the neck crest become more pronounced?
☐ Are there unusual fat deposits around the tail head, shoulders or other areas?
☐ Has my horse previously suffered from laminitis?
☐ Has laminitis occurred without an obvious explanation?
☐ Does my horse have multiple metabolic risk factors?
☐ Am I relying on appearance alone to decide whether my horse is metabolically healthy?
☐ Have I reviewed the horse's complete diet, including forage and pasture?
☐ Have I discussed metabolic testing with my veterinary surgeon where appropriate?
If several answers are “yes”, it may be worth having a conversation with your vet.
Frequently Asked Questions
What are the early signs of EMS in horses?
Possible clues include abnormal regional fat deposits, easy weight gain, difficulty losing weight, a pronounced neck crest and a history of laminitis. However, these features do not diagnose EMS, and insulin dysregulation can occur in horses without obvious obesity.
Can a horse have EMS without being overweight?
Yes. Insulin dysregulation and adiposity are not inseparably linked. EMS can occur in horses with a relatively lean phenotype.
Does a cresty neck mean my horse has EMS?
No. A cresty neck can be associated with metabolic risk and has been studied as a predictor of insulin dysregulation, particularly in ponies, but it is not diagnostic on its own.
Does laminitis mean my horse has EMS?
No. Laminitis has multiple causes. However, endocrinopathic laminitis associated with insulin dysregulation is an important consideration, particularly in horses with other metabolic risk factors.
How is EMS diagnosed?
Diagnosis involves consideration of the horse's history and clinical findings together with appropriate laboratory assessment of insulin dysregulation. The choice and interpretation of testing should be made with veterinary guidance.
Can a normal-looking horse have insulin dysregulation?
Yes. Body condition is useful for assessing risk but cannot reliably determine insulin status.
What should I feed a horse with suspected EMS?
The diet should be individually formulated around appropriate calorie intake, forage, carbohydrate exposure and nutritional requirements. Weight management and pasture control may also be important. See our guide to the Best Diet for a Horse With EMS for more detail.
Can supplements cure EMS?
No. Supplements should not be presented as a cure for EMS. Long-term management focuses primarily on appropriate diet, weight management, exercise where appropriate and veterinary monitoring.
Can EMS be managed long term?
Yes. EMS management is generally a long-term process. Dietary management and appropriate exercise are central to improving insulin regulation and reducing obesity where present.
Final Thoughts
The biggest mistake owners can make when thinking about EMS is to reduce it to:
“My horse is fat, therefore it has EMS.”
The science is more complicated.
EMS centres on insulin dysregulation and increased risk of endocrinopathic laminitis. Excess body fat and regional adiposity are important risk factors, but they do not tell the whole story.
Some horses are obviously overweight.
Some have pronounced regional fat deposits.
Some are difficult to slim down.
And some may have insulin dysregulation without looking particularly abnormal at all.
The most sensible approach is therefore to consider the whole horse:
Body condition + fat distribution + diet + pasture + exercise + laminitis history + veterinary assessment.
If you are concerned about EMS, don't wait until your horse develops obvious laminitis before taking metabolic health seriously.
Early recognition gives you the opportunity to review management, investigate insulin dysregulation where appropriate and work with your veterinary team to reduce future risk.
At Dr Silver, we believe nutritional supplements should complement good feeding and evidence-based horse management — not replace them.
The horse comes first. Always.
Scientific References
Durham AE, Frank N, McGowan CM, et al. (2019). ECEIM consensus statement on equine metabolic syndrome. Journal of Veterinary Internal Medicine, 33(2), 335–349. DOI: 10.1111/jvim.15423.
Frank N, Tadros EM. (2014). Insulin dysregulation. Equine Veterinary Journal, 46(1), 103–112. DOI: 10.1111/evj.12169.
Fitzgerald DM, Anderson ST, Sillence MN, de Laat MA. (2019). The cresty neck score is an independent predictor of insulin dysregulation in ponies. PLoS ONE, 14(7), e0220203. DOI: 10.1371/journal.pone.0220203.
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