Cushing Syndrome Complications in Horses

Managing the serious secondary conditions that arise from equine Cushing disease (PPID) and preserving quality of life in affected horses.

Key Facts

Pituitary pars intermedia dysfunction (PPID) affects an estimated 15–30% of horses over 15 years
Elevated ACTH in PPID horses dramatically increases laminitis risk — the leading welfare-critical complication
Hypertrichosis (failure to shed a thick coat) is often the first sign owners notice
Pergolide mesylate treatment reduces ACTH concentrations and laminitis episodes by 50–70%
PPID horses have impaired immune function and are more susceptible to dental disease and parasites
Muscle wasting (topline loss) reflects protein catabolism driven by chronic elevated cortisol

Welfare Considerations

PPID creates a cascade of welfare harms: the laminitic episodes that follow uncontrolled ACTH spikes cause severe and often refractory pain; the inability to thermoregulate because of the retained coat causes heat stress; and chronic infection from immunosuppression compounds suffering. Early diagnosis via blood ACTH testing before obvious clinical signs allows pergolide treatment to begin before the first laminitic crisis. Welfare-conscious management includes seasonal coat clipping, dental checks every six months and targeted small-redworm faecal egg count monitoring. Palliative end-of-life decisions should be considered promptly when laminitis becomes unmanageable.

What You Can Do

Test ACTH levels annually from age 15 and biannually during the autumn seasonal rise (August–October)
Start pergolide as soon as PPID is confirmed — do not wait for obvious symptoms to worsen
Clip hypertrichotic horses in spring and summer to prevent dangerous heat stress
Feed a forage-based, low-sugar diet and avoid lush pasture to reduce laminitis trigger
Maintain regular six-monthly dental checks as PPID causes accelerated tooth loss
Work with a vet and farrier team experienced in laminitis to manage hoof mechanics proactively