Cushing's Disease in Horses (PPID): Symptoms, Treatment, and Management

What Is Cushing’s Disease in Horses (PPID)?

Cushing’s disease in horses, medically known as Pituitary Pars Intermedia Dysfunction (PPID), is one of the most common hormonal disorders affecting older horses and ponies. It is caused by a dysfunction of the pituitary gland, a vital part of the brain that regulates hormone production. As the condition progresses, the pituitary gland enlarges and begins to overproduce certain hormones, most notably adrenocorticotropic hormone (ACTH), which disrupts the horse's hormonal balance and leads to a wide range of health issues.

While “Cushing’s disease” is the more familiar term among horse owners—borrowed from a similar condition in humans—the correct veterinary term is Pituitary Pars Intermedia Dysfunction (PPID). These two names refer to the same condition in horses and are used interchangeably in both clinical and everyday contexts.

PPID primarily affects horses over the age of 15, but it can also develop in younger horses. If left untreated, PPID can lead to serious complications, including laminitis, muscle wasting, immune suppression, and behavioral changes. Fortunately, with early diagnosis and proper management, many horses with PPID can continue to live long, active, and healthy lives.

Symptoms of Cushing’s Disease in Horses (PPID)

The signs of Cushing’s disease in horses, also known as Pituitary Pars Intermedia Dysfunction (PPID), can vary significantly from horse to horse. The disease progresses slowly, and its symptoms range from subtle behavioral changes to obvious physical deterioration. In many cases, the early signs are mistakenly attributed to aging, which makes early detection particularly challenging.

What are the first signs of Cushing’s disease in horses?

PPID often begins with changes that are easy to overlook:

• Fatigue or low energy without clear cause
• Dull or patchy coat
• Slight weight loss
• Reduced performance or reluctance to work

These early symptoms of mild Cushing’s in horses can mimic normal aging or overlap with other conditions like Equine Metabolic Syndrome (EMS), laminitis, or equine asthma, making diagnosis difficult.

Common physical symptoms of PPID in horses

As the disease progresses, more noticeable signs develop. The three most characteristic symptoms are:

• A long, curly or shaggy coat that doesn’t shed properly
• Muscle loss, especially along the topline and back
• Laminitis, which affects roughly 50% of PPID horses if left untreated

Recent research has shown that up to 70% of laminitis cases in autumn are linked to undiagnosed Cushing’s disease, due to impaired sugar metabolism and insulin resistance.

📖 Must Read: Horses with Cushing’s are at high risk of developing laminitis. This article explains what causes it, how to spot early signs, and how to respond effectively.

Additional symptoms of Cushing’s disease in horses:

Recognizing these symptoms early is vital. Untreated Cushing’s disease in horses can lead to chronic laminitis, organ dysfunction, and declining quality of life. The good news is that, with early diagnosis and treatment, PPID in horses can be managed effectively, allowing horses to remain active and healthy for many years.

What Causes Cushing’s Disease in Horses (PPID)?

Pituitary Pars Intermedia Dysfunction (PPID), commonly known as Cushing’s disease in horses, originates from a malfunction in the brain’s hypothalamic-pituitary axis. As horses age, dopaminergic neurons in the hypothalamus begin to degenerate, reducing the brain's production of dopamine—a chemical that normally keeps the pituitary gland in check.

When this inhibition is lost, the intermediate lobe of the pituitary gland becomes overactive, releasing excessive amounts of adrenocorticotropic hormone (ACTH). This overstimulation leads to a cascade of hormonal disruptions, including chronically elevated cortisol levels produced by the adrenal glands.

Consequences of hormonal imbalance

• Elevated cortisol puts the body in a chronic stress state
• Immune suppression, making the horse more vulnerable to infections
• Insulin resistance, leading to abnormal fat deposits and laminitis
• Muscle wasting and overall energy loss
• Possible pituitary enlargement or benign adenomas (tumor-like growths)

What triggers dopamine loss in PPID horses?

While aging is the most significant risk factor, other contributors include:

• Oxidative stress or chronic inflammation
• Diets rich in sugar and starch, which stress the endocrine system
• Long-term corticosteroid use, potentially disrupting feedback mechanisms
• Genetic predisposition (though not yet clearly proven)

Can Cushing’s disease in horses be prevented?

There’s no guaranteed prevention, but early lifestyle management helps:

• Maintain a low-sugar, high-fiber diet
• Encourage regular, low-stress movement
• Minimize exposure to chronic stress or harsh training
• Avoid overuse of glucocorticoid medications
• Monitor older horses (15+ years) regularly for subtle signs

The earlier you recognize risk factors, the more likely you are to delay the onset or lessen the severity of this hormonal disorder.

How Is Cushing’s Disease Diagnosed in Horses?

Diagnosing Cushing’s disease in horses (PPID) requires a combination of clinical observation and laboratory testing. Since the early symptoms of Cushing’s disease in horses can be vague or easily mistaken for normal aging, diagnosis often begins with a suspicion based on coat changes, muscle loss, or behavioral shifts.

Veterinarians typically confirm a PPID diagnosis through blood testing, especially by measuring levels of ACTH (adrenocorticotropic hormone).

ACTH Blood Test

The endogenous ACTH test is the most common diagnostic method. Elevated ACTH levels are a strong indicator of PPID. However, these values naturally vary by season, making timing critical.

ACTH reference values:

• November to July: < 29 pg/mL considered normal
• August to October: < 47 pg/mL normal; values > 100 pg/mL strongly suggest PPID

For accurate results, avoid testing after stress, exercise, or sedation, as these can artificially raise ACTH levels.

TRH Stimulation Test

If the baseline ACTH test is inconclusive—especially in early-stage or mild cases—a TRH (thyrotropin-releasing hormone) stimulation test may be recommended. This test assesses the pituitary gland’s responsiveness by measuring ACTH levels before and after administering TRH. It's considered more sensitive for detecting early PPID.

Best time to test for Cushing’s in horses

The late summer and early fall (August to October) are ideal, as ACTH levels naturally rise in all horses. However, PPID horses show a more exaggerated seasonal increase, making comparisons more accurate.

Treatment of Cushing’s Disease in Horses (PPID)

Although Cushing’s disease in horses (PPID) cannot be cured, it is very manageable—especially when diagnosed early. With the right combination of medication, adapted management, and nutritional support, most horses with PPID can live active, comfortable lives for many years.

Prascend for Horses: The Gold Standard in PPID Treatment

The most commonly prescribed and currently the only licensed medication for treating PPID in horses is Prascend (active ingredient: pergolide mesilate). It acts as a dopamine agonist, replacing the dopamine that is no longer produced in sufficient amounts by the hypothalamus. This helps regulate the pituitary gland and reduces the overproduction of ACTH, stabilizing cortisol levels in the body.

Typical dosage:

• 0.5–1 mg per 100 kg of body weight per day, depending on the severity of symptoms
• The dose may be adjusted over time based on clinical response and follow-up blood tests

Most horses show clear improvement within a few weeks: more energy, fewer symptoms, and reduced risk of laminitis and secondary infections.

Managing Side Effects

When starting Prascend, some horses may experience:

• Temporary loss of appetite
• Lethargy
• Mild signs of colic

These symptoms usually fade after a short adjustment period. In some cases, a gradual dosage increase over 7–10 days can help minimize initial side effects.

Lifelong Monitoring Is Essential

Because Cushing’s is a chronic condition, ongoing management is critical. Your horse should:

• Receive annual ACTH testing, ideally in late summer or fall
• Be monitored for changes in coat, appetite, and hoof health
• Have the dose of Prascend adjusted as needed over time

Supportive Measures Beyond Medication

To give your PPID horse the best possible care, it’s essential to go beyond medication. Thoughtful daily management can help prevent complications like laminitis, weight loss, and infections, all while supporting your horse’s overall well-being. The following table outlines the most important supportive measures and how they contribute to managing Cushing’s disease in horses effectively:

Is There a Natural Treatment for Cushing’s in Horses?

‍Some owners explore natural approaches to support PPID management, such as monk’s pepper (Vitex agnus-castus), adaptogenic herbs, or antioxidant-rich supplements. While these may help support the endocrine system, they cannot replace Prascend in horses with moderate to severe PPID. Always discuss natural treatments with your vet before starting.

Feeding Horses with Cushing’s Disease (PPID)

Proper nutrition plays a central role in managing Cushing’s disease in horses, especially when it comes to minimizing the risk of laminitis, supporting muscle maintenance, and compensating for nutrient imbalances caused by hormonal disruption or medication.

Since many PPID horses also suffer from insulin resistance, the diet must be carefully tailored to reduce sugar and starch intake, while still providing enough energy, fiber, and essential micronutrients.

➡ Must Watch: Grain-free feeding – is it the more natural choice? Horses aren’t designed to digest large amounts of grain, yet it’s common in modern feeding routines. Learn why that is, how grain affects digestion, and whether a grain-free diet is truly better. Equine nutritionist Dr. Felicitas Drebes shares science-based insights.

Basic Feeding Guidelines for PPID Horses

• Prioritize low-sugar, high-fiber forage, such as late-cut hay or soaked hay (30–60 min) to reduce water-soluble carbohydrates
• Avoid grain, molasses, and sweet feeds, which spike blood sugar and exacerbate symptoms
• Maintain consistent feeding times to stabilize metabolism
• If the horse has dental issues, consider hay pellets or soaked roughage substitutes

Feeding Overweight Cushing’s Horses

For horses with PPID and obesity, the goal is to reduce body fat gradually without triggering a metabolic crisis:

• Limit total dry matter intake to 1.5% of body weight per day
• Use slow-feeder hay nets to extend eating time
• No pasture access during high-fructan periods (spring/fall); use a grazing muzzle if turnout is necessary
• Use desugared beet pulp as a fiber-rich energy source, if needed

Feeding Lean or Muscle-Wasting PPID Horses

In advanced stages, some horses lose muscle mass or become underweight despite a good appetite. In these cases:

• Provide high-quality protein sources such as alfalfa, soybean meal, or soaked hay cobs
• Add essential amino acids (lysine, methionine, threonine) to support muscle repair
• Supplement with vitamin E, omega-3 oils (e.g., linseed oil), and desugared beet pulp to add safe calories

Important Supplements for PPID Horses

• A low-starch, low-sugar mineral feed with high bioavailability is essential
• Pay attention to magnesium, vitamin E, selenium, and zinc
• Milk thistle, nettle, and dandelion can support liver and kidney function
• Vitamin C (e.g., rosehip powder) may help support the immune system
• Some owners use monk’s pepper (Vitex agnus-castus) to support hormone balance—check with your vet before use

Living with Cushing’s Disease: What Your Horse Needs Most

Cushing’s disease in horses (PPID) is a serious but manageable condition. While the syndrome can’t be cured, a combination of targeted treatment, adapted feeding, and supportive daily care can significantly improve your horse’s quality of life.

The key to success lies in early detection, ongoing veterinary guidance, and your commitment as a horse owner to recognizing subtle changes and adjusting care routines accordingly. With Prascend, proper nutrition, and consistent monitoring, many horses with PPID can stay active, comfortable, and happy for many years.

If your horse is showing signs of coat changes, weight loss, or recurring laminitis, don’t wait—speak to your vet about testing for Cushing’s. The earlier you act, the more you can do to protect your horse’s long-term health and well-being.

Cushing's Disease in Horses (PPID): Frequently Asked Questions

How long can a horse with Cushing’s live?

There’s no universal answer, as each case is different. However, with early diagnosis and consistent treatment—especially with Prascend for horses—many horses live well into their late 20s or even 30s. Some PPID horses have been known to reach 37 years of age with proper care.

How much does a Cushing’s or ACTH test cost?

Costs vary by location, but you can expect around €60 or more for the vet’s visit and blood draw, plus lab fees. If PPID is diagnosed, monthly medication costs for Prascend typically range between €60–120. Additional costs may arise if the horse requires laminitis treatment or specialist farrier care.

Can I ride a horse with Cushing’s disease?

Yes, but carefully. While high cortisol levels should be avoided, gentle, regular exercise is important to prevent muscle loss and weight gain. Always tailor the workload to the horse’s condition, with long warm-up and cool-down phases. If in doubt, opt for groundwork or light hacking instead of intensive training.

How can I prevent Cushing’s disease in horses?

You can’t fully prevent PPID, but you can support your horse’s metabolic health through:

• Species-appropriate feeding
• Low-stress management
• Plenty of movement
• Avoiding excess weight
  These strategies help reduce the risk of hormonal imbalance over time.

What medication is used to treat Cushing’s disease in horses?

The go-to treatment is Prascend (active ingredient: pergolide mesilate), which helps regulate ACTH production and stabilize cortisol levels. It’s typically administered once daily and adjusted based on your horse’s response.

Can a Cushing’s horse still go out to pasture?

Yes, but pasture access should be limited and closely monitored, especially during times of high grass sugar content (spring and fall). A grazing muzzle can help control intake and reduce the risk of laminitis.

What happens if Cushing’s disease in horses is left untreated?

Untreated PPID can lead to severe complications such as:

• Chronic laminitis
• Weakened immune function
• Organ stress and failure
  Eventually, it may reduce your horse’s quality of life and lifespan.

When should a Cushing’s horse be euthanized?

This decision depends on the horse’s individual condition and comfort level. If pain from laminitis or secondary issues becomes unmanageable despite treatment, euthanasia may be the kindest option. Always consult your vet.

Can a horse with Cushing’s be used for breeding?

Breeding is not recommended. PPID can cause fertility issues in mares and pregnancy puts enormous strain on the endocrine system. For the horse’s wellbeing, breeding should be avoided.

Is Cushing’s disease fatal for horses?

Not directly. But if left untreated, PPID can lead to fatal secondary issues, especially laminitis. With early diagnosis, proper feeding, and medication, horses with Cushing’s often live full, high-quality lives.