Last updated: April 28, 2026
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If your older horse isn’t shedding normally, is drinking more than usual, or just doesn’t look quite like himself anymore — don’t wait. 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.
Managing Cushing’s disease (PPID) in horses — the short version:
- What it is: PPID is a pituitary disorder that drives excess hormone production — progressive, not reversible, but manageable with the right approach
- Earliest sign: Delayed shedding in spring — coat still long after other horses have shed
- Diagnosis: Blood test — resting ACTH, or TRH stimulation test for borderline cases. Use seasonally adjusted reference ranges.
- Medication: Pergolide (Prascend) — FDA-approved, daily for life, dose adjusted by ACTH retesting
- Diet: NSC under 10% is the common target for horses with confirmed insulin dysregulation. Hay must be tested.
- Key rule: A horse can be on the right pergolide dose and still develop laminitis if diet isn’t controlled. Medication and NSC management must work together.
This guide is based on my 30+ years of hands-on experience owning and managing Thoroughbreds at Fair Grounds, Evangeline Downs, and Delta Downs (Louisiana Racing License #67012). I am not a licensed veterinarian. The management strategies shared here reflect practices used in my own barn and are provided for educational purposes only.
PPID, insulin dysregulation, and laminitis interact in ways that require individual assessment. Always consult with a licensed equine veterinarian before starting, stopping, or changing any medication or making major diet changes for a horse with Cushing’s disease.
Table of Contents
What Is PPID / Cushing’s Disease?
Cushing’s disease in horses — more accurately called PPID (Pituitary Pars Intermedia Dysfunction) — is a pituitary disorder. In a healthy horse, the brain keeps this gland regulated. With age, that control breaks down and hormone production increases — especially ACTH. The result is the symptoms owners recognize: abnormal coat changes, weight loss, and increased thirst. The underlying cause is gradual loss of dopamine-producing nerve cells that normally keep the pituitary in check.
The AAEP classifies PPID as one of the most common endocrine disorders in older horses:
- Common in older horses: Most cases diagnosed around 18–20 years of age
- Progressive but manageable: Not curable, but long-term control is achievable with treatment
- Key risk factor: Commonly linked with insulin dysregulation, which increases laminitis risk
- Early detection matters: Outcomes are significantly better before laminitis develops
Recognizing the Signs — Checklist and Staging
The goal is to catch PPID before secondary problems develop — especially laminitis. The Equine Endocrinology Group consensus guidelines emphasize that early-stage diagnosis — before laminitis — dramatically improves long-term outcomes.
- Delayed shedding in spring — coat still long after other horses have shed
- Increased drinking and urination — noticeably more water intake than normal
- Loss of topline muscle mass — hollowing behind the withers, weak hindquarters
- Potbelly appearance — despite normal or reduced food intake
- Fat deposits above the eyes, at the tailhead, or along the crest — distinctive “cresty neck” appearance
- Abnormal sweating — either excessive or reduced; wet patches in unusual places
- Recurring or unexplained laminitis — especially without a clear dietary trigger
- Lethargy or reduced performance — less interest in work, slower recovery
- Chronic infections — skin, foot, or dental infections that are slow to resolve
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.
| Stage | Common Signs | What Owners Often Think |
|---|---|---|
| Early (Stage 1) | Delayed coat shedding in spring; subtle muscle wasting over topline; slightly increased drinking | “Just getting older” / “Bad shedding year” |
| Moderate (Stage 2) | Obvious long, curly coat; potbelly; visible muscle loss over hindquarters; fat pads above eyes and at tailhead | “That coat is really unusual” / “She’s losing condition” |
| Advanced (Stage 3) | Recurring laminitis; chronic infections; weight loss despite adequate feed; lethargy | Damage is already advanced |
Getting a Diagnosis
If you suspect PPID, call your veterinarian. Diagnosis is confirmed with bloodwork — not observation. Most cases are confirmed quickly with a simple blood test.
The ACTH Blood Test
Resting plasma ACTH is the standard first test. A blood sample is drawn and sent to a lab; elevated ACTH above the seasonally adjusted reference range strongly indicates PPID. ACTH naturally rises in all horses during autumn (Aug–Oct), so seasonal ranges matter — a horse that looks borderline in spring may test clearly positive in fall. Results should always be interpreted alongside clinical signs, since stress or improper sample handling can elevate ACTH.
The TRH Stimulation Test
When ACTH is borderline but signs are present, the TRH stimulation test is more sensitive for early PPID. A baseline ACTH is drawn, TRH is injected, and a second sample drawn 10 minutes later — an exaggerated response confirms PPID even at near-normal resting levels.
Medication: Prascend and 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 restores hormonal control and reduces ACTH production. It does not cure PPID, but it is highly effective at controlling clinical signs and normalizing ACTH.
| Factor | Details |
|---|---|
| Starting dose | Typically 0.5–1 mg/day; vet-determined based on weight and ACTH level. Some vets now recommend starting at 0.25 mg to reduce side effects. |
| Titration | Dose adjusted based on ACTH retest at 4–6 weeks; many horses stabilize at 1–2 mg/day |
| Early side effects | Reduced appetite in first 1–2 weeks (“pergolide veil”) — usually managed by starting at a lower dose and titrating up slowly |
| Monitoring | ACTH retested 4–6 weeks after any dose change; minimum annually, biannually for advanced cases |
| Seasonal adjustment | Many horses need a proactive dose increase in late summer/autumn (Aug–Oct) to compensate for the natural ACTH seasonal rise |
| Cost | Brand Prascend ~$45–65/month at 1 mg; compounded pergolide available at $20–35/month — see the Cost section for a full breakdown |
Compounded pergolide is widely used and significantly cheaper than Prascend. Both are effective, but compounded formulations can vary in stability and dosing accuracy depending on the compounding pharmacy — quality is not uniform.
Nutrition: The Most Critical Pillar
Diet determines whether a PPID horse develops laminitis. A horse can have normal ACTH on pergolide and still founder if diet isn’t controlled. In PPID horses with insulin dysregulation, nutrition is primary prevention — not supportive care.
Insulin Dysregulation: The Driver of Laminitis Risk
Many horses with PPID also develop insulin dysregulation (ID). High-NSC feed triggers excessive insulin, which disrupts hoof laminae function — leading to pain, inflammation, and structural failure.
The Central Target: NSC Under 10%
NSC (non-structural carbohydrates) is the combined sugar and starch in feed and forage.
| NSC Level | Status for PPID Horse |
|---|---|
| Under 10% | ✅ Safe — target for all PPID horses with confirmed insulin dysregulation |
| 10–12% | ⚠️ Caution — acceptable only for PPID horses without confirmed ID, with vet approval |
| Over 12% | ❌ High risk — avoid in all actively managed PPID horses |
Hay: Test Everything
Hay NSC varies by cutting, curing, and growing conditions — the same farm’s hay can shift from 7% to 13% between seasons. The only reliable method is testing. Hay testing costs $20–40 per sample through Equi-Analytical or your local extension office. Test every new batch. For more on choosing low-NSC hay for metabolic horses, see the horse hay feeding guide.
| Feed | Status | Notes |
|---|---|---|
| Sweet feed / corn / oats | ❌ Eliminate | High NSC — laminitis trigger regardless of pergolide status |
| Ration balancers (Enrich Plus, Crypto Aero) | ✅ First choice | Delivers protein, vitamins, minerals without caloric load; ideal for easy keepers |
| Triple Crown Low Starch | ✅ Safe | 4.7% starch — formulated specifically for insulin-resistant horses |
| Purina WellSolve L/S | ✅ Safe | Low-NSC senior feed option; useful for horses needing weight support |
| Beet pulp (unmolassed, soaked) | ✅ Safe | High fiber, low NSC energy source; excellent for senior horses with dental issues |
| Flaxseed / flax oil | ✅ Safe | Omega-3 source; anti-inflammatory; 1–2 oz oil or ground flax daily |
| Alfalfa (straight forage) | ⚠️ Caution | High protein supports weight; but NSC can be high — test before feeding; limit portion size |
Sample Daily Feeding 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
- 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 a management tool for PPID horses that are sound enough to work. Regular movement improves insulin sensitivity, supports muscle maintenance, aids digestive motility, and supports healthy weight. The rule: exercise is appropriate when the horse is not in an active laminitis episode and comfortable at the walk.
| Horse Status | Appropriate Exercise | Avoid |
|---|---|---|
| PPID, no laminitis, good muscle mass | Regular light to moderate work — 20–40 min, 4–5 days/week | Hard footing; very deep sand if joints are compromised |
| PPID, no laminitis, muscle wasting | Begin with daily handwalking 15–20 min; build to light riding over 8–12 weeks | Long sessions early; downhill work before hindquarter strength returns |
| PPID, recovered laminitis, vet-cleared | Handwalking on firm, level ground; gradual return to riding per vet timeline | Any work until vet-cleared; circles before straight-line comfort is established |
| Active laminitis episode | Stall rest; deep shavings; follow vet protocol | All exercise including turnout until episode resolves |
Hoof Care and Laminitis Prevention
Laminitis risk in PPID horses is driven mainly by metabolism, not mechanics — diet and insulin control determine the risk, hoof care supports the outcome. Elevated insulin alters normal function in the hoof laminae, weakening the attachment between the hoof wall and the coffin bone. For a full guide to preventing and managing laminitis in horses with metabolic disease, see the linked guide.
The Three Pillars of Laminitis Prevention
Effective prevention requires consistent management across three areas: NSC control through tested low-NSC diet and managed pasture access; medical management through correct pergolide dosing adjusted by ACTH retesting; and hoof support through consistent farrier care and baseline monitoring. Each one matters.
Hoof Care Protocol for PPID Horses
- Farrier every 6–8 weeks without exception — hoof imbalance increases mechanical stress on already-vulnerable laminae; do not stretch the interval
- Provide consistent, forgiving footing — deep shavings year-round, not just during active episodes; PPID horses with thin soles need cushioning as a baseline
- Plan proactively with your farrier — horses at higher risk may benefit from supportive trimming or therapeutic shoeing before problems develop
- Maintain a written laminitis action plan with your vet — contact number, initial steps, when to call vs. when to trailer. Speed of response in the first 24 hours changes outcomes.
- Reluctance to move, shortened stride, or the horse standing with front feet stretched forward to offload weight
- Increased digital pulse or heat in the hooves — especially the front feet — compared to your established baseline
- Sudden stiffness, especially when turning
- Marked appetite loss after starting pergolide — mild reduction is common in the first week; complete refusal is not
- Rapid or unexplained weight loss, or recurring infections that don’t resolve normally
Managing the Whole Horse: Arthritis, Weight, and Dental Health
PPID rarely travels alone in older horses — the same aging processes affect joints, muscle mass, body weight, and dentition.
Equine arthritis and joint pain are common in horses aged 18–25, which is also peak PPID age. Cortisol elevation from PPID can mask pain signals — horses may be more uncomfortable than they appear. For an overview of managing arthritis alongside PPID, 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. See the guide on why horses lose weight and how to address it — the causes covered there 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.
Seasonal Management: Spring Pasture and Autumn Rise
Spring — The Highest-Risk Period
Spring grass can reach 25–35% NSC. That level drives insulin spikes in sensitive horses — high-NSC intake → exaggerated insulin release → lamellar disruption → laminitis.
NSC is not constant throughout the day. It accumulates during sunlight and peaks mid-to-late afternoon. Cool nights followed by sunny days spike levels further. Managing spring risk means accounting for that daily variability, not just limiting total hours.
- Dry lot or restricted turnout — the most reliable way to control NSC intake
- Grazing muzzle if turnout is necessary — reduces intake by 50–80%, but does not eliminate risk; effectiveness varies by horse
- Early morning turnout only — NSC peaks mid-afternoon
- Hay fed before any turnout — pre-loading the gut moderates the insulin response to grass intake
- Do not rely on limited turnout alone — exposure, not duration, drives risk
Autumn — The ACTH Seasonal Rise
All horses rise in ACTH from August through October. In PPID horses, that rise is stronger and often breaks previous control — the most common point of treatment failure in otherwise well-managed cases. Horses who appeared stable all summer may redevelop delayed shedding, lethargy, muscle loss, or increased laminitis risk starting in late August. If you wait for visible symptoms in autumn, you are already behind the hormonal shift.
- Retest ACTH in early–mid September using seasonally adjusted reference ranges — do not use spring ranges for autumn results
- Adjust pergolide dose based on results, not clinical signs alone — waiting for symptoms means the horse has already lost hormonal control
- For horses with prior autumn instability: consider a proactive dose increase in late July or early August; retest in September to confirm
- Do not assume a previously effective dose remains adequate — the seasonal rise regularly breaks through doses that worked all summer
- 1. Feed — This Is Where Laminitis Starts (or Doesn’t): Sugar and starch drive the problem. Keep total NSC under 10% if the horse has insulin issues; test every load of hay; cut out grain and sweet feed completely. You can have a horse perfectly dosed on pergolide and still founder him with the wrong hay.
- 2. Laminitis — It’s an Insulin Problem, Not Just a Cushing’s Problem: High-NSC feed → insulin spike → laminae weaken → horse founders. Biggest triggers: spring grass, fall regrowth, and untested hay. Good trimming helps, but it doesn’t stop metabolic laminitis.
- 3. Spring — This Is Where Most Horses Get in Trouble: Best option is dry lot during the flush. If they go out: grazing muzzle, early morning only, hay fed first. A short turnout on rich spring grass can be enough — it’s not about how long.
- 4. Autumn — Where Good Programs Quietly Fall Apart: Test ACTH in September. Adjust pergolide based on results, not how the horse looks. The horse can look fine in August and be out of control hormonally by September.
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.
| Expense | Typical Cost | Frequency |
|---|---|---|
| Prascend (brand, 1 mg/day) | $45–65/month | Ongoing — daily for life |
| Compounded pergolide (1 mg/day) | $20–35/month | Ongoing — daily for life |
| ACTH blood test | $40–80 per test | Minimum 2x/year (spring + autumn) |
| Hay NSC testing (Equi-Analytical) | $20–40 per sample | Every new batch — typically 4–8x/year |
| Farrier visits (every 6–8 weeks) | $60–150 per visit | 6–8x/year; more if therapeutic shoeing needed |
| Ration balancer / supplements | $40–80/month | Ongoing |
| Single laminitis episode (vet + farrier + stall rest) | $2,000–10,000+ | Preventable with proper management |
FAQs About Cushing’s Disease in Horses
What is the life expectancy of a horse with Cushing’s disease?
With proper management — medication, tested low-NSC diet, regular monitoring, and proactive hoof care — most horses diagnosed with PPID live many comfortable years after diagnosis. Quality of life is the more relevant measure than life expectancy. Horses managed well from Stage 1 frequently remain in light work for 5–8 years after diagnosis. Horses not diagnosed until advanced Stage 3 or that have sustained significant laminitis damage have a more difficult prognosis — which is why early detection matters so much.
Can a horse recover from Cushing’s disease?
PPID is not reversible — the pituitary dysfunction is progressive and does not resolve. What is achievable is controlling it well enough that the horse lives comfortably and secondary complications (laminitis, infection, weight loss) are minimized or prevented. ‘Recovery’ in the practical sense means a well-managed PPID horse that looks, behaves, and performs similarly to before diagnosis — and many horses get there.
What is the best hay for a horse with Cushing’s disease?
Tested low-NSC hay — timothy, orchard grass, or bermudagrass that tests under 10% NSC. Grass species matters less than the actual test result. Late-cut, mature hay is generally lower in NSC than early-cut, leafy hay — but only a test confirms it. Soak hay for 60 minutes in cold water to reduce NSC by 20–30% if a batch tests borderline. For more on hay selection, see the horse hay feeding guide.
How often should I test ACTH in a horse with PPID?
At minimum: test at diagnosis, retest 4–6 weeks after starting or adjusting medication, and test annually (or biannually for advanced cases). Many vets recommend testing in both spring (March–April) and autumn (August–October) to catch the seasonal ACTH rise and adjust medication proactively. Any time clinical signs worsen, an unscheduled ACTH test is warranted.
Should a horse with Cushing’s be on pergolide for life?
Yes. PPID is a progressive disease and the pituitary dysfunction does not resolve. Stopping pergolide results in return of elevated ACTH and recurrence of clinical signs. Dose may be adjusted upward over years as the disease progresses, but discontinuation is not the goal of treatment.
What triggers laminitis in horses with Cushing’s disease?
In PPID horses, laminitis is triggered by insulin dysregulation — not elevated ACTH directly. High-NSC intake (spring pasture, grain, untested hay) causes an abnormal insulin spike, which disrupts normal function in the hoof laminae, altering blood flow and weakening the lamellar attachment. This is why a horse can be on the correct dose of pergolide and still develop laminitis if diet isn’t controlled. Both medication and NSC-controlled diet must be in place simultaneously.
Is PPID the same as insulin resistance in horses?
No — but the two commonly occur together. PPID is a pituitary gland dysfunction causing hormone imbalance. Insulin dysregulation (ID) is a metabolic condition where the horse produces an exaggerated insulin response to sugar intake. PPID can cause or worsen insulin dysregulation, but a horse can have one without the other. Both require separate testing to confirm: ACTH testing for PPID, and an oral sugar test (OST) or basal insulin test for insulin dysregulation. Managing both conditions is the standard of care for most PPID horses.
Can a horse with Cushing’s eat grass?
Yes, but not unmanaged spring pasture, and not unlimited access at any time of year if the horse has confirmed insulin dysregulation. Managed grass access — dawn/dusk turnout on mature summer grass, with a grazing muzzle, after feeding hay first — is achievable for many PPID horses in lower-risk seasons. Spring and autumn require stricter control or dry lot management. Every horse is different; the horse’s insulin status and laminitis history determine how much pasture restriction is necessary.
- 1. Feed — Control Sugar and Starch: Most laminitis starts here. Keep NSC under 10% for horses with insulin issues. Test every batch of hay. No grain. No sweet feed.
- 2. Medication — Dose Based on Testing, Not Appearance: Pergolide works, but only at the right dose. Retest after changes and at least twice a year. A horse can look fine and still be out of range.
- 3. Spring — This Is the Highest-Risk Window: Fresh grass drives insulin spikes. Limit or eliminate pasture during the flush. If turnout is necessary: muzzle, early morning, hay first.
- 4. Autumn — Stay Ahead of the Hormone Shift: Test ACTH in September using seasonal ranges. Adjust pergolide before symptoms show. Waiting means you’re already behind.
Related guides in the senior horse series:
About Miles Henry
Racehorse Owner & Author | 30+ Years in Thoroughbred Racing
Miles Henry (legal name: William Bradley) is a professional horseman based in Folsom, Louisiana. He holds Louisiana Racing License #67012 and has spent over three decades managing Thoroughbreds at premier tracks including Fair Grounds, Delta Downs, and Evangeline Downs.
Expertise & Hands-On Experience: Beyond the track, Miles has decades of experience in specialized equine care, covering everything from hoof health and nutrition to training protocols for Quarter Horses, Friesians, and Paints. Every guide on Horse Racing Sense is rooted in this “boots-on-the-ground” perspective.
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