EMS in horses: what you really need to know

What exactly is EMS?

EMS stands for equine metabolic syndrome and is a hormonal-metabolic condition in which the horse's cells become less sensitive to insulin. Normally, insulin ensures that glucose passes from the blood into the cells. In an insulin-resistant horse, blood sugar levels remain elevated for too long, causing the pancreas to produce ever-increasing amounts of insulin. These chronically high insulin levels eventually damage the blood vessels in the hooves, which can cause laminitis. EMS is not a condition that can be 'cured', but with the right approach you can greatly reduce symptoms and largely prevent laminitis episodes.

Which horses are most at risk?

Not every horse is equally susceptible to EMS. Certain breeds and types are genetically more predisposed, but lifestyle also plays a major role.

• Ponies such as Welsh, Shetland and Fjord
• Warmblood and coldblood crosses that gain weight easily
• Horses older than 10 years with a diet low in variety
• Horses with a cresty neck score of 3 or higher (scale 0–5)
• Horses that eat large amounts of sugar-rich grass without sufficient exercise

The most important symptoms at a glance

EMS often develops gradually. Many owners believe for years that their horse is simply overweight. Watch out for these signs:

• Fat deposits in the neck (cresty neck), above the eyes or at the tail base
• Difficulty losing weight despite reduced feed intake
• Regularly warm hooves or sensitivity on hard ground
• Recurring or chronic laminitis, even without an obvious cause
• Fatigue and reduced performance during light exercise

How is EMS diagnosed?

The vet confirms EMS through blood tests. The most commonly used test is the fasting insulin measurement, where a value above 20–30 µIU/ml (depending on the laboratory) is considered suspicious. An additional dynamic insulin test can be performed, measuring the response to a sugar load. ACTH is sometimes also measured to rule out the related condition PPID (pituitary pars intermedia dysfunction, formerly known as Cushing's) — both conditions frequently occur together. Record in your horse's EquiSight horse profile when blood values were taken, so you can easily track trends over time.

Adjusting nutrition: the biggest lever

Feed is the single most important variable in managing EMS. The key rule is: limit non-structural carbohydrates (NSC) to less than 10% of the total ration.

• Have your grass analysed: grass in spring and after drought can sometimes contain more than 25% NSC
• Use a grazing muzzle or restrict pasture access to a maximum of 1–2 hours per day at safe times
• Soak hay for 30–60 minutes in water to wash out sugars (reduces NSC by 20–40%)
• Do not give fruit, carrots or grain-rich treats as snacks
• Ensure adequate magnesium, vitamin E and selenium through a tailored mineral supplement

Exercise as part of the treatment

Regular exercise directly increases the insulin sensitivity of muscles, comparable to the effect seen in people with type-2 diabetes. For horses with active laminitis, only begin exercise with the vet's approval. Once the horse is stable, build up gradually: 20 minutes of walking per day is already beneficial. After 4–6 weeks, aim for at least 3 to 4 training sessions per week during which the horse is clearly active. Use the EquiSight calendar to track training sessions and hoof temperature, so you can quickly see whether exercise is having a positive effect or is causing discomfort.

Monitoring: keeping a close watch

EMS requires long-term, structured follow-up. One blood test per year is not enough.

• Weigh or estimate body weight monthly using a tape measure (girth and body length)
• Assess the cresty neck score every 4–6 weeks using photos for comparison
• Repeat blood tests every spring, when weight increases or after a laminitis episode
• Record all findings in your horse's EquiSight horse profile for easy reference at the vet
• Ask EquiCoach for a personalised monitoring schedule based on the data you have entered