Cushing’s Disease (PPID) in Horses: Causes, Symptoms, Diagnosis & Management
PPID is the most common endocrine disorder in older horses. Here’s how it works, what to watch for, how ACTH/TRH testing is used (with seasonal interpretation), how treatment and daily management fit together—and how to hydrate smart with sugar-free support.
What is PPID?
Pituitary Pars Intermedia Dysfunction (PPID), often called equine Cushing’s disease, is a neuroendocrine condition of older horses. The dopamine-producing neurons that normally keep the pituitary’s pars intermedia in check begin to degenerate. With less dopamine, the pars intermedia becomes overactive, releasing excess hormones that drive many of the clinical signs riders notice.
PPID is distinct from EMS, but a single horse can have both. PPID increases laminitis risk and requires life-long management with veterinary oversight.
Common Signs & Red Flags
- Delayed or incomplete shedding; long, curly, or “shaggy” hair coat (hirsutism)
- Muscle loss/topline wasting; pot-bellied appearance or weight/condition changes
- Lethargy, reduced performance; increased drinking and urination
- Recurrent infections, skin issues, or hoof abscesses
- Increased risk of laminitis, especially during seasonal transitions
Heads-Up Some horses show only subtle early changes (slower shedding, “off” energy, foot sensitivity). Early testing helps you get ahead of the curve.
Diagnosis: ACTH & TRH Testing
Basal ACTH (with Seasonal Ranges)
Veterinarians commonly start with a plasma ACTH test. Interpretation should use seasonally adjusted reference ranges because ACTH rises naturally in late summer/fall. Results are assessed alongside clinical signs.
TRH Stimulation Test
In horses with suggestive signs but normal/equivocal ACTH, a TRH stimulation test can reveal early PPID. Your vet will time sampling precisely and interpret against season-appropriate cutoffs.
Pro Tip Testing conditions matter. Follow your vet’s pre-test instructions (e.g., fasting or feeding guidance) and recheck after therapy adjustments or seasonally to stay dialed-in.
Treatment & Monitoring
- Pergolide is the most commonly prescribed medication for PPID. Dosing is individualized and adjusted to effect under veterinary supervision.
- Vets often reassess ACTH/TRH 4–8 weeks after starting or adjusting therapy, then monitor at regular intervals along with clinical signs.
- Expect a team approach: veterinary care, farrier management, dentistry, parasite control, and nutrition all matter.
Safety Handle medications exactly as instructed. Do not crush tablets unless your vet provides specific guidance.
Daily Management: Diet, Hooves, Care
1) Diet & Body Condition
- Prioritize low-NSC forage. Many PPID horses also have insulin dysregulation—limit sugars/starches and monitor weight.
- Use a ration balancer/mineral to cover vitamins and minerals without calorie overload.
2) Hoof & Laminitis Prevention
- Keep a tight farrier schedule for balance/support and watch closely for heat, pulses, or shortness of stride.
3) Senior Wellness
- Stay current on dentistry, parasite control, and routine bloodwork. Note subtle changes in energy, coat, and feet.
Sugar-Free Hydration & Comfort
Hydration Without Sugar
PPID horses—especially those with insulin dysregulation—benefit from sugar-free electrolyte plans:
Hydro-Lyte™ supports hydration without added sugars, fitting senior and metabolic management.
Keep Work Comfortable
For day-to-day comfort during conditioning, choose sensation-free topical support:
PPID — FAQ
Is PPID curable?
PPID is a lifelong condition. The goal is control—reducing clinical signs and laminitis risk with medication and management.
How quickly will I see improvement after starting treatment?
Some horses show improvement in weeks; others need dose adjustments and seasonal tweaks. Vets often recheck labs 4–8 weeks after dose changes and monitor clinical progress across seasons.
Does every PPID horse need medication?
Medication decisions are individualized. Many horses benefit from pergolide, but your veterinarian will weigh signs, lab data, and overall risk to guide therapy.
What about clipping the coat?
Clipping can keep a horse cooler and more comfortable while medical therapy and seasonal shedding are managed.
Can PPID and EMS occur together?
Yes. Co-existing insulin dysregulation is common, so diet and hoof management remain core priorities even with medical treatment.
Educational note: This article is for general information and is not a substitute for veterinary diagnosis or treatment. Always consult your veterinarian for personalized advice.
