Managing Cushing’s Disease (PPID) in Horses: A Complete Guide

Last updated: March 31, 2026

By: Miles HenryFact Checked

If your older horse isn’t shedding normally, is drinking more than usual, or just doesn’t look quite like himself anymore, you’re right to pay attention. Those subtle changes are often the first signs of PPID—and the owners who catch them early are the ones whose horses are still going strong years later. One of those horses was a 22-year-old Quarter Horse named Rosie, diagnosed three years ago and still on trail rides today because her owner acted early.

After 30-plus years owning and racing Thoroughbreds at the Fair Grounds, Evangeline Downs, and Delta Downs—along with a lifetime with pleasure horses and working Quarter Horses—I’ve watched PPID go from something rarely discussed to one of the most common diagnoses in older horses today.

This guide breaks down exactly how to manage it—from diagnosis and medication to low-NSC feeding and laminitis prevention—so you can catch it early and keep your horse going strong.

What Is PPID / Cushing’s Disease?

Cushing’s disease in horses—more accurately called PPID—starts in a small part of the brain called the pituitary gland. It’s not the same condition seen in dogs or humans, and that matters because horses develop it differently and require different treatment.

In a healthy horse, the brain keeps this gland under control. As horses age, that control weakens, and the gland begins producing too many hormones—especially ACTH. This hormone imbalance leads to the symptoms owners recognize, including abnormal coat changes, weight loss, and increased thirst. This breakdown is linked to the gradual loss of dopamine-producing nerve cells that normally keep the pituitary in check.

According to the American Association of Equine Practitioners (AAEP), PPID is one of the most commonly diagnosed endocrine disorders in older horses. Here are the key facts every owner should know:

Recognizing the Signs — Checklist and Staging

One of the most important things you can do for an older horse is recognize PPID before it has caused secondary damage — specifically before laminitis sets in. The Equine Endocrinology Group, which publishes the clinical consensus guidelines most equine vets follow, emphasizes that early-stage diagnosis — before laminitis — dramatically improves long-term outcomes. The challenge is that early signs are easy to dismiss as normal aging.

The single most important early signal is a coat that doesn’t shed normally in spring. If your horse still has significant winter coat in June in a warm climate — or in July anywhere — that is worth a vet call. By the time the classic potbelly-and-long-coat picture is obvious, the horse has likely had PPID for years.

Getting a Diagnosis

If you suspect PPID, your next step is to call your veterinarian. Diagnosis is confirmed through blood testing — not guesswork. Several conditions can look similar, including hypothyroidism, equine metabolic syndrome, and chronic liver disease. Most cases are confirmed quickly with a simple blood test.

The ACTH Blood Test

Resting plasma ACTH is the test most vets run first and is the standard starting point for diagnosis. A blood sample is drawn and sent to a lab. Elevated ACTH — above the lab’s seasonally adjusted reference range — strongly indicates PPID. Results usually arrive within a few days.

One important nuance: ACTH levels rise naturally in all horses during the autumn (August through October). Because of this, reference ranges change by season. A horse tested in September will naturally read higher than the same horse in March.

Make sure your vet is using seasonally adjusted ranges. Some horses that look borderline in the spring test clearly positive in autumn.

The TRH Stimulation Test

For horses with clinical signs but borderline ACTH results, the TRH (thyrotropin-releasing hormone) stimulation test is more sensitive for early or borderline cases. A baseline ACTH is drawn, TRH is injected, and a second ACTH is drawn 10 minutes later. An exaggerated response confirms PPID even when resting ACTH is near the reference range. This test is particularly useful for catching early-stage cases before clinical signs become obvious.

Medication: Prascend / Pergolide

The standard treatment for PPID is pergolide mesylate, sold under the brand name Prascend — the only FDA-approved equine formulation. Pergolide is a dopamine agonist that replaces the function of the depleted dopaminergic neurons and suppresses the overproduction of ACTH from the pituitary. It does not cure PPID, but in the majority of horses it significantly reduces clinical signs, normalizes ACTH, and when combined with proper nutrition, dramatically reduces laminitis frequency.

Compounded pergolide is widely used and significantly cheaper than Prascend. Both are effective, but compounded formulations vary in potency. If your horse’s ACTH stays elevated on compounded pergolide at a dose that previously worked, switching to brand Prascend for a period is worth discussing with your vet.

Nutrition — The Most Critical Pillar

Medication controls the hormonal dysfunction. Diet is what keeps the consequences — particularly laminitis — from materializing even when medication is working. For a PPID horse with insulin dysregulation, a single high-starch meal can trigger a laminitis episode regardless of how well the pergolide is working. Diet is not optional support; it is front-line management.

For a deeper foundation on equine feeding principles, see the complete horse nutrition guide. For strategies specific to the aging horse, including dental-friendly feed options and managing weight loss, see the feeding guide for senior horses.

Insulin Dysregulation: The Hidden Risk Factor

Many horses with PPID also develop insulin dysregulation (ID) — and understanding this connection is what separates owners who prevent laminitis from those who treat it repeatedly without understanding why it keeps happening.

Insulin dysregulation means the horse produces an excessive insulin response to sugar intake, even when blood glucose is normal. The result: a PPID horse eats a high-NSC meal, insulin spikes far higher than it should, and that spike causes vasoconstriction in the hoof’s laminar blood vessels — cutting off circulation to the sensitive structures that keep the coffin bone attached to the hoof wall. That is laminitis. And it can happen even when the horse’s ACTH is well-controlled on pergolide.

This is the reason a horse can be on the right medication at the right dose and still develop laminitis. The medication addresses the hormone problem; diet addresses the insulin problem. Both pillars must be in place simultaneously. Pergolide without NSC control is an incomplete protocol.

The Central Target: NSC Under 10%

NSC — non-structural carbohydrates — is the sum of sugar and starch in forage and feed. High-NSC intake spikes blood insulin in PPID horses with insulin dysregulation, triggering the blood vessel spasm in the hoof laminae that causes laminitis. The target is straightforward:

Hay: Test Everything

Hay is the foundation of the PPID diet — and the source of the most common dietary mistake. NSC content cannot be estimated by appearance or species alone. Timothy hay that looks identical side by side can test at 6% NSC or 14% NSC depending on when it was cut, how it was cured, and the soil conditions it grew in. The only way to know is to test it.

Hay testing costs $20–40 per sample through services like Equi-Analytical or your local extension office. That $30 test prevents $5,000–$10,000 in laminitis treatment. Test every new batch — not once a season. For more on how to choose low-NSC hay for horses with metabolic conditions, including what to look for on a hay analysis report, see the full guide.

Sample Daily Feeding Schedule — 1,100-lb PPID Horse

Sample Daily Schedule — 1,100-lb PPID Horse

• 6:00 AM 3 lbs tested low-NSC timothy hay (<8% NSC)
• 6:15 AM 1–2 lbs ration balancer + 1 oz flaxseed oil + daily Prascend tablet (hidden in small amount of soaked beet pulp)
• 12:00 PM 3 lbs timothy hay + fresh water check + salt block access
• 4:00 PM 3 lbs timothy hay
• 6:30 PM 3 lbs timothy hay + 1 lb soaked beet pulp (if weight support needed) + 1 oz flaxseed oil

Exercise for Cushing’s Horses

Exercise is not optional for PPID horses that can tolerate it — it is a management tool. Regular movement improves insulin sensitivity, supports muscle maintenance (which PPID actively degrades), aids digestive motility, and supports a healthier weight. The risk is exercising through a laminitis episode, which causes serious and often permanent damage. The rule: exercise is appropriate when the horse is not in an active laminitis episode and is comfortable moving at the walk. For specific conditioning approaches for horses over 15, see the exercise and conditioning guide for senior horses.

Hoof Care and Laminitis Prevention

Laminitis is the most serious and most preventable complication of PPID. The mechanism: elevated insulin causes vasoconstriction in the hoof’s laminar blood vessels, depriving the sensitive laminae of blood, causing them to weaken and separate from the hoof wall. In severe cases this leads to rotation or sinking of the coffin bone — conditions that end performance careers and often end horses’ lives.

Prevention is almost entirely diet-based (NSC control and pasture management) combined with medication keeping ACTH normalized. But active hoof care plays an essential supporting role. For a full guide to preventing laminitis in horses with metabolic disease, including founder recovery protocols, see the linked guide.

Managing the Whole Horse: Arthritis, Weight, and Dental Health

PPID rarely travels alone in older horses. The same aging processes that affect the pituitary also affect joints, muscle mass, body weight, and dentition. Managing PPID well means managing the whole horse — not just the one diagnosis.

Equine arthritis and joint pain are common in horses aged 18–25, which is also peak PPID age. The combination of arthritis pain and laminitis pain can make lameness assessment genuinely difficult — and cortisol elevation from PPID can mask some pain signals, meaning horses may be more uncomfortable than they appear. For an overview of managing arthritis in older horses, including when NSAIDs are appropriate and how to structure a joint support program, see the equine arthritis guide for horse owners and the guide to NSAIDs in horses.

Body weight can go either direction. Some PPID horses are obese — PPID combined with insulin dysregulation produces a horse that gains weight despite apparently normal intake and deposits fat at the cresty neck, tailhead, and above the eyes. Others are severely underweight — muscle wasting from elevated cortisol, combined with dental issues and poor nutrient absorption, creates a horse that can’t hold condition. Both need different dietary approaches but the same NSC discipline. For detailed guidance on why horses lose weight and how to address it, the causes covered in that article frequently overlap with PPID complications.

Dental health is often the unacknowledged limiting factor in PPID diet management. A horse that can’t chew hay effectively can’t get adequate forage regardless of how well you source it. Annual dental exams are baseline for any horse over 15. For horses with significant dental compromise, soaked hay cubes, beet pulp, and commercial senior feeds replace long-stem forage as the fiber source — these products are designed for exactly this situation.

Seasonal Management: Spring Pasture and Summer Heat

Spring — The Highest-Risk Period

Spring grass — actively growing, driven by warming temperatures and long days — is the single highest-NSC forage a horse encounters. NSC in spring pasture commonly reaches 25–35%. For a PPID horse with any insulin dysregulation, unmanaged spring pasture access is a laminitis setup. The risk period generally runs from late February through June depending on your climate.

Autumn — The ACTH Seasonal Rise

August through October brings a natural rise in ACTH in all horses — a seasonal phenomenon not related to disease severity. In PPID horses, this rise is exaggerated and can break through previously adequate medication control. Horses who were well-managed all spring and summer may begin showing signs again — muscle wasting, coat changes, elevated laminitis risk — starting in late August. Anticipate this with your vet: many PPID horses benefit from a proactive dose increase in late July or early August. Retest ACTH in September to confirm.

What Doesn’t Work — and Why

Waiting to see if it gets worse before medicating is one of the most common and costly mistakes. PPID is progressive. The time to medicate is when ACTH is confirmed elevated — not when the horse has already had a laminitis episode.

Managing with diet alone without medication addresses the consequences but not the cause. Horses managed on diet alone without pergolide typically continue to deteriorate and face higher risk for severe laminitis episodes.

Assuming “senior feed” means low-NSC is a widespread misunderstanding. Many commercial senior feeds contain enough starch and sugar to be problematic for PPID horses with insulin dysregulation. “Senior” means formulated for aging digestive systems — it does not mean metabolically safe. Check the guaranteed analysis; anything over 12% combined NSC requires scrutiny.

Herbal supplements as primary treatment — Chasteberry (Vitex agnus-castus) has been studied as a natural dopamine agonist. Evidence for meaningful ACTH reduction is weak, and it is not a substitute for pergolide in a confirmed PPID diagnosis. It may have a minor supportive role but should never replace veterinary treatment.

Restricting hay to control weight frequently backfires. Forage restriction in overweight PPID horses causes hindgut dysfunction, ulcers, and metabolic stress. The answer is low-NSC hay fed at adequate quantities, not hay restriction.

What Does It Cost to Manage a Horse with Cushing’s Disease?

Cost is one of the first practical questions owners ask after a PPID diagnosis, and it deserves a direct answer. Managing equine Cushing’s disease is not cheap, but it is predictable — and the biggest costs are avoidable if you manage proactively. One laminitis episode costs more than a full year of proper PPID management.

A year of well-managed PPID — brand Prascend, twice-yearly ACTH testing, regular hay testing, and consistent farrier care — runs approximately $1,500–2,500 annually depending on medication choice and hay volume. One preventable laminitis episode costs more than that. Proactive management is also the cheaper approach.

Common Questions About Cushing’s Disease (PPID) in Horses

Conclusion

PPID is a diagnosis — not a life sentence. The horses that struggle are the ones caught late, managed inconsistently, or managed with diet alone without medication — or medication alone without diet. The ones that thrive are the ones where the owner did the work: got the ACTH test, started pergolide at the right dose, tested the hay, managed spring pasture, and stayed in contact with their vet.

Rosie — the 22-year-old Quarter Horse that sparked this guide — is still going. Trail rides, quiet turnout, a coat that sheds on time now. Her owner did three things right in the first 30 days after diagnosis, and everything else followed from that foundation.

If Your Horse Was Just Diagnosed — Start Here

• 01. Schedule an ACTH test and medication conversation with your vet — confirm the diagnosis, get the pergolide dose right, and build the monitoring schedule.
• 02. Test your hay for NSC content — every new load, not once a season. This $20–40 investment is the single most important dietary step you can take.
• 03. Audit your horse’s current diet for hidden sugars and starches — review every feed label, pull anything over 12% NSC, and replace grain-based feeds with a ration balancer and tested forage.

Is your horse dealing with a late-shedding coat, recurring laminitis, or unexplained weight changes? Drop a comment below — I’d love to hear your story and share what’s worked in my barn.

About the Author: Miles Henry (William Bradley) is a lifelong horseman and Louisiana-licensed racehorse owner (License #67012). He has spent decades hands-on with Thoroughbreds and Quarter Horses at tracks including Fair Grounds, Evangeline Downs, and Delta Downs, with a focus on equine health management and the practical intersection of barn experience and current veterinary science.