What exactly is Equine Cushing's Disease?

Equine Cushing's Disease, more accurately known as Pituitary Pars Intermedia Dysfunction (PPID), is a hormonal condition that primarily affects older horses and ponies. The pituitary gland, a small but mighty structure at the base of the brain, begins to malfunction. Specifically, the pars intermedia region loses its normal regulation, leading to an overproduction of hormones such as ACTH and others. This disrupts the horse's entire endocrine system, affecting everything from coat growth to metabolism and immune function. While it is most common in horses over 15 years old, it can appear earlier. Native breeds and ponies may be more prone, but any horse can develop it. The good news is that with understanding and consistent management, many horses with Cushing's continue to enjoy a good quality of life for years.

Spotting the signs: more than just a curly coat

The classic image of a Cushing's horse is one with a long, curly coat that fails to shed in spring. However, that is often a later sign. Early symptoms can be subtle and easily attributed to old age. Watch for:

• Delayed or incomplete shedding, leaving a thick, sometimes curly coat well into summer.
• Lethargy and poor stamina – your horse may seem unwilling to work as before.
• Weight loss despite a healthy appetite, often with a pot-bellied appearance and loss of muscle along the topline and hindquarters.
• Increased drinking and urination (polydipsia and polyuria).
• Recurrent infections – abscesses, sinusitis, or skin conditions that linger.
• Laminitis, sometimes the first obvious sign. UK grazing, especially lush spring or autumn pasture, can tip a borderline case into a painful episode.

In the UK, our variable weather and rich grass can mask or worsen these signs. A horse that has always been a good doer may suddenly struggle. Trust your instincts – if something feels off, ask your vet.

Getting a diagnosis: what to expect from your vet

Diagnosing PPID is not as simple as a single blood test, but your vet has reliable tools. The most common test is a resting ACTH blood sample. However, ACTH levels naturally rise in autumn (the seasonal rise), so testing in late summer or autumn can give false positives. Many vets recommend testing in spring or early summer, or using a TRH stimulation test for clarity. Your vet may also check insulin levels, as Cushing's often goes hand in hand with insulin dysregulation and laminitis risk. The test itself is straightforward: a blood sample, usually from the jugular vein, sent to a laboratory. Results, combined with clinical signs, give a diagnosis. Do not fast your horse unless your vet specifically asks – it is not usually necessary. Once diagnosed, you have a baseline for monitoring treatment.

Daily management: diet, routine and environment

Management is the cornerstone of care, and it is very practical. The goal is to control hormone levels (with medication if prescribed) and reduce the risk of laminitis and other complications.

Diet: Feed a low-sugar, low-starch diet. Soak hay for 12 hours if it is high in sugars (this can reduce water-soluble carbohydrates by up to 30%). Use a grazing muzzle, strip graze, or turn out on a dry lot or poor pasture. Avoid lush spring and autumn grass. Feed little and often, and choose a balancer rather than a high-calorie mix. Fresh water always available.

Routine: Keep a consistent daily schedule. Gentle exercise, if your horse is comfortable, helps with circulation, digestion and mood. Even hand-walking or light hacking is beneficial. Regular farrier visits are essential – laminitis can change hoof shape. Book dental checks every six to twelve months, as Cushing's horses are prone to periodontal disease.

Environment: Provide shelter from sun, rain and flies. Cushing's horses often struggle to thermoregulate. In winter, they may need a rug, but avoid over-rugging. In summer, clip if the coat is thick, and use fly protection. Good ventilation in the stable helps prevent respiratory infections.

Medication and monitoring: the long game

If your vet prescribes medication, the most common is pergolide, given daily as a small tablet or powder. It works by mimicking dopamine, which helps regulate the pituitary gland. It is not a cure, but it controls the condition. You will likely see improvement in coat, energy and appetite within a few weeks to months. Regular blood tests – usually every six to twelve months, or after any dose change – monitor ACTH levels. Your vet may adjust the dose based on results and clinical signs. Never stop medication suddenly. Side effects can include lethargy, loss of appetite or diarrhoea, but these often settle. If you notice anything unusual, call your vet. Some owners also explore herbal support, such as chasteberry, but always discuss with your vet first, as it can interact with prescription medication.

Living well: adjusting care as they age

Cushing's is a progressive condition, but many horses live comfortably for years with good management. As your horse ages, their needs will change. Monitor body condition score monthly. Watch for subtle signs of pain or laminitis – a shortened stride, reluctance to turn, or a bounding digital pulse. Keep a diary of symptoms, medication and test results. Work closely with your vet, farrier, dentist and equine nutritionist. In the UK, our wet winters and rich summers require extra vigilance. A horse with Cushing's can still enjoy hacking, gentle schooling or simply being a companion. The key is patience, routine and a willingness to adapt. You know your horse best – if something changes, speak up. With the right care, your veteran can continue to thrive in their familiar rural surroundings.