What Are the Early Signs of Cushing’s Disease (PPID) in Horses?

Cushing’s disease in horses — properly called Pituitary Pars Intermedia Dysfunction (PPID) — often develops quietly. Long before the classic long, curly hair coat appears, subtle changes in muscle tone, energy, immunity, and hoof health can signal a problem. Recognizing these early signs allows veterinarians to diagnose PPID sooner, begin treatment earlier, and dramatically reduce the risk of complications like laminitis.

At Countryside Equine Hospital, early detection is the goal — because PPID is far easier to manage before it disrupts a horse’s quality of life.

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

PPID is caused by a slow-growing, benign tumor in the pituitary gland, located at the base of the brain. This tumor disrupts normal hormone regulation and leads to excessive production of cortisol.

Cortisol affects nearly every tissue in the body, which is why PPID doesn’t present as one obvious symptom — it shows up as a pattern of small changes over time.

Importantly, PPID:

• Develops gradually
• Worsens with age
• Cannot be cured, but can be very well managed

Early Signs of PPID Most Horse Owners Miss

Many horses with PPID look “off” long before they look “sick.” These early changes are easy to overlook or chalk up to aging.

Common early signs include:

• Muscle loss along the topline, especially through the back and hindquarters
• A pot-bellied appearance despite normal or reduced feed
• Difficulty maintaining weight or muscle
• Lethargy or decreased stamina
• Subtle personality changes — quieter, duller, less engaged

These changes are often mistaken for “just getting older,” which delays diagnosis.

Why the Hair Coat Is a Late Sign — Not an Early One

One of the most persistent myths about Cushing’s disease is that you’ll know a horse has it because of a long, shaggy hair coat.

In reality, delayed shedding and abnormal hair growth usually occur late in the disease process.

“One of the biggest misconceptions I hear is, ‘My horse can’t have Cushing’s because he doesn’t have the long hair coat.’ That’s actually one of the last symptoms to appear.”
— Dr. Zoe Latimer, DVM

By the time the hair coat changes are obvious, PPID has often been affecting the horse internally for months or even years.

This is why Countryside emphasizes looking for earlier, subtler indicators rather than waiting for obvious outward signs.

Immune System Changes: A Major Early Clue

Elevated cortisol suppresses the immune system, and this often shows up early in PPID cases.

Watch for:

• Recurrent skin infections or “rain rot”
• Chronic scratches or flaky skin
• Dental infections or sinus drainage
• Difficulty clearing parasite loads
• Wounds that heal slowly or not at all

Eye injuries, particularly corneal ulcers that fail to heal like they should, are another common red flag.

When a horse suddenly struggles to fight off things it used to handle easily, PPID should be on the diagnostic radar.

Hoof Changes and the Link to Laminitis

Laminitis is one of the most serious complications associated with PPID.

Early hoof-related signs may include:

• White line stretching and toe pain
• Increased sensitivity on hard ground
• Difficulty maintaining previously healthy feet
• Farrier noting changes in hoof quality

Farriers are often the first to notice these changes, making vet–farrier communication critical in early detection.

How PPID Is Diagnosed: Why TRH Testing Matters

Testing is the only way to confirm PPID.

Common diagnostic options include:

• Baseline ACTH testing
• TRH stimulation testing (preferred for early cases)

TRH stimulation testing allows veterinarians to detect PPID before ACTH levels are dramatically elevated, making it especially valuable for horses in the early or subclinical stages of disease.

At Countryside, this proactive approach helps veterinarians work to identify PPID before laminitis or major systemic effects occur.

What Happens After Diagnosis?

While PPID cannot be cured, it can be extremely well managed.

Treatment typically includes:

• Daily administration of FDA-approved pergolide (Prascend)
• Careful dosing and consistency
• Follow-up testing after approximately six weeks
• Ongoing monitoring over the horse’s lifetime

When managed early and correctly, many horses:

• Regain muscle tone
• Improve immune function
• Have fewer infections
• Regain energy and brightness
• Live comfortable, active lives well into their senior years

Quality of Life: What Owners Can Expect

One of the most reassuring aspects of early PPID diagnosis is how much quality of life can improve with treatment.

Owners often report:

• A brighter attitude
• Increased energy
• Better body condition
• Fewer recurring health issues

PPID management is about restoring comfort, function, and enjoyment for both horse and owner.

When Should a Horse Be Tested for Cushing’s Disease?

Testing should be considered when:

• A horse is 12–15 years or older
• Subtle muscle or weight changes appear
• Immune-related issues become frequent
• Hoof quality changes without explanation
• Energy or demeanor declines

Testing can be done at any time of year. It is important to trust your veterinarian to interpret test results appropriately, as seasonal hormone fluctuations can affect the detection and diagnosis of PPID.

How This Fits Into the Bigger Picture

PPID often overlaps with:

• Insulin resistance
• Equine Metabolic Syndrome

That’s why diagnosing one metabolic condition often leads veterinarians to screen for others. Early detection allows for comprehensive management, not reactive care.

Commonly Asked Questions

What are the earliest signs of Cushing’s disease in horses?
Early signs include muscle loss, lethargy, immune system issues, poor wound healing, subtle hoof changes, and changes in body condition.

Is a long hair coat always present with PPID?
No. Abnormal hair growth is typically a late-stage sign and should not be relied on for early detection.

How is PPID diagnosed in horses?
PPID is diagnosed through blood testing, with TRH stimulation testing commonly used to identify early cases.

Can horses live a normal life with Cushing’s disease?
Yes. With early diagnosis and proper management, many horses live long, comfortable, and active lives.

When is the best time of year to test for PPID?
Spring is one of the most effective times to test due to seasonal hormone changes that make PPID easier to detect.

If you found this article helpful and want to experience compassionate, diagnostically-driven equine care, Countryside Equine Hospital is the place for you. Locally owned and privately operated, we’ve been proudly serving our local community since 1991. With integrity at the heart of our care, we deliver progressive medicine and exceptional service

Do you have an equine medical question or concern? We’re here for your horse day and night, offering 24/7/365 emergency care when it matters most. Give us a call at (770) 787‑4711 or visit us at 3395 Maughon Road, Covington, GA  30014. You can also learn more  and request an  appointment on our website at countrysideeq.com.

Published By

Dr. Rachel Akin