Understanding Cushing’s disease and EMS

Subtle changes in your horse’s coat, weight or energy levels may signal more than simple ageing. Hormonal conditions often develop gradually, but with early diagnosis and careful management, many horses can lead comfortable, active lives.

So what is Cushing’s disease, and what is equine metabolic syndrome? And how do you recognise the early warning signs?

What are Cushing’s disease and equine metabolic syndrome?

Cushing’s disease in horses, properly known as pituitary pars intermedia dysfunction (PPID), and equine metabolic syndrome (EMS) are the two most common endocrine disorders affecting horses.

The endocrine system controls hormones – the chemical messengers that regulate metabolism, stress responses and immune function. When that system becomes disrupted, the effects can be wide-ranging.

What is Cushing’s disease?

Often referred to as equine Cushing’s disease, this condition develops when part of the pituitary gland becomes overactive. Over time, this leads to excessive production of certain hormones, including cortisol, which can affect metabolism, immune response and muscle tone.

It is most commonly seen in older horses and ponies, and tends to develop slowly – sometimes over several years.

What is equine metabolic syndrome?

Equine metabolic syndrome is a condition linked to insulin dysregulation. Horses with EMS produce abnormally high levels of insulin and are often prone to weight gain and fat deposits. The most serious associated risk is laminitis.

Unlike Cushing’s, EMS is often seen in younger or middle-aged ‘good doers’ – particularly native breeds and ponies.

The symptoms of Cushing’s disease and EMS

One of the challenges with both conditions is that symptoms can be subtle at first.

Common Cushing’s disease symptoms include a long or curly coat that doesn’t shed properly, muscle loss along the topline, increased drinking and urination, lethargy and recurrent infections. Laminitis may also be a warning sign. Because some of these changes can resemble normal ageing, they are sometimes overlooked.

Typical equine metabolic syndrome signs tend to centre around weight gain. Horses may develop a thick, cresty neck or fat deposits around the shoulders or above the tail. Episodes of laminitis are often the first clear indication that something isn’t right.

If you notice gradual changes in your horse’s weight, coat or energy levels, it’s always worth discussing them with your vet. Early investigation can make a real difference.

Diagnosis and why early action matters

Diagnosis of Cushing’s disease in horses or equine metabolic syndrome usually involves a physical examination alongside blood tests to assess hormone and insulin levels. Your vet will also consider your horse’s history and any recent changes.

Neither condition will go away on its own. Both are progressive, so they tend to worsen if left unmanaged. The earlier they are identified, the easier they are to control – and the better the long-term outlook for your horse.

Treatment of Cushing’s disease and EMS

There is no cure for either condition, but effective treatment options for both Cushing’s disease and equine metabolic syndrome are available.

For equine Cushing’s disease, a medication called pergolide is commonly prescribed to regulate hormone production. This treatment is typically lifelong, with regular monitoring to ensure the dosage remains appropriate.

EMS has two main treatments available – metformin, which increases the tissue’s sensitivity to insulin, and ertugliflozin (and related drugs), which reduces insulin levels by lowering blood glucose. However, management is usually the most important element of treatment and should focus on careful weight control, dietary adjustments and increased exercise where suitable. Improving insulin sensitivity is central to reducing the risk of laminitis.

Ongoing veterinary guidance is important, as treatment plans often need to be adjusted over time.

Because both conditions require ongoing veterinary care and monitoring, it’s sensible to review your horse insurance policy and understand what’s covered.

Diet and long-term management

Diet plays an important role in equine metabolic syndrome management.

If you’re considering what to feed a horse with EMS, the priority is reducing sugar and starch intake. Soaked hay, unmolassed chaff, restricted grazing and low-calorie balancers are often recommended. Simply feeding less is rarely enough; the type of feed matters as much as the quantity.

A structured equine metabolic syndrome diet, combined with appropriate exercise, can dramatically reduce the risk of laminitis.

Owners sometimes explore equine metabolic syndrome supplements or natural remedies. While some products may support metabolic health, they should complement – not replace – veterinary advice.

For horses with Cushing’s disease, good routine care is equally important. Regular dental checks, vaccinations, parasite control and careful weight monitoring all help support a compromised immune system. Clipping may be necessary if the coat becomes excessively thick, particularly during warmer months.

Can equine metabolic syndrome be reversed?

While EMS cannot be ‘cured’ in the strict sense, many horses regain normal insulin regulation with strict weight management and consistent care so that medical treatment is no longer needed. Early intervention offers the best chance of long-term control.

Cushing’s disease, by contrast, is a lifelong condition. However, with appropriate medication and management, many horses continue to enjoy a good quality of life for years after diagnosis.

The key with both Cushing’s disease and equine metabolic syndrome is vigilance. Subtle changes in weight, coat or behaviour are often the earliest indicators. Prompt veterinary advice, tailored diet and treatment plans, and consistent monitoring can help reduce complications and keep your horse comfortable. With the right care and support, a diagnosis need not define your horse’s future.