Equine Metabolic Syndrome in Horses

Equine Metabolic Syndrome (EMS) is a complex and increasingly common condition that affects horses and ponies across the UK. It’s important for owners to understand the risks, recognise the signs, and manage the condition carefully to protect their horse’s health. In this blog post, we’ll cover what EMS is, why it happens, how to spot it, and what you can do to help.

What is Equine Metabolic Syndrome?

Equine Metabolic Syndrome is a hormonal and metabolic disorder that affects how a horse’s body regulates insulin. It’s characterised by:

• insulin dysregulation (insulin resistance)
• abnormal fat deposits (regional adiposity)
• an increased risk of laminitis

EMS is similar in some ways to type 2 diabetes in humans, but in horses, it’s more often associated with an increased tendency to develop laminitis.

Why Does EMS Occur?

The primary cause of EMS is insulin dysregulation. In affected horses, the body’s tissues become less sensitive to insulin (insulin resistance). As a result, the pancreas produces more insulin to try to keep blood sugar levels normal.

Over time, this high level of insulin in the bloodstream (hyperinsulinaemia) can trigger laminitis by affecting blood flow to the sensitive tissues of the hoof.

EMS is often seen in horses and ponies that:

• are overweight or obese
• are native or hardy breeds (e.g., Welsh, Shetland, Dartmoor, Connemara)
• have a genetic predisposition to store fat easily

Risk Factors

Certain factors can increase the risk of EMS developing, including:

• obesity and excessive body condition
• diets high in sugars and starches (e.g., lush grass, cereals)
• lack of exercise
• age (EMS can develop at any age, but it’s more common in middle-aged horses)

Recognising EMS in Horses

EMS can sometimes be tricky to identify because it often develops gradually. Common signs include:

• abnormal fat deposits: a “cresty” neck, fat pads behind the shoulders, at the base of the tail, or around the eyes
• difficulty losing weight despite dietary control
• episodes of laminitis, particularly without obvious dietary triggers

Subtle signs of insulin dysregulation may include:

• increased thirst
• increased urination
• lethargy or reluctance to exercise

If you notice any of these signs, it’s important to involve your vet as soon as possible for a proper diagnosis.

Diagnosing EMS

Diagnosis usually involves:

• a thorough clinical examination, including assessment of body condition and fat distribution
• blood tests to measure insulin levels (fasting insulin, dynamic tests like the oral sugar test)
• evaluation of laminitis history and risk

Your vet may also assess glucose levels and other markers of metabolic health to get a complete picture.

Managing EMS

Effective management of EMS revolves around addressing insulin dysregulation and reducing the risk of laminitis.

Dietary Management

• reduce non-structural carbohydrates (sugars and starches) in the diet
• feed soaked hay to reduce sugar content (soak for 1-2 hours in cold water)
• avoid lush grazing, especially in spring and autumn
• provide a balanced, low-calorie diet with essential vitamins and minerals

Weight Management

• gradual weight loss is key for overweight horses (aim for 0.5-1% of body weight loss per week)
• use a weigh tape or scales to monitor progress
• restrict access to rich pasture or use a grazing muzzle

Exercise

• regular, controlled exercise helps improve insulin sensitivity and encourages weight loss
• exercise plans should be tailored to the horse’s current health status, especially if laminitis is present

Veterinary Support and Medications

• your vet may recommend medications such as metformin to help manage insulin resistance, although this is not always necessary
• regular monitoring of insulin levels and hoof health is essential

Laminitis and EMS

Laminitis is a serious complication of EMS. Horses with EMS are at a higher risk of laminitis, even with relatively small dietary changes. If your horse develops laminitis, veterinary treatment is vital, and dietary and management strategies must be adjusted to avoid further episodes.

Final Thoughts

Equine Metabolic Syndrome is a challenging but manageable condition. With the right care, many horses and ponies with EMS can live healthy, active lives. Key points to remember:

• recognise the signs of EMS early
• work with your vet to develop a tailored management plan
• prioritise weight control, dietary changes, and regular exercise
• keep a close eye on any signs of laminitis

If you’re concerned about EMS in your horse, don’t hesitate to contact your vet for advice and support. Early intervention can make all the difference in managing this condition successfully.