PPID (Cushing's Disease)

• What is PPID?

  PPID (Pituitary Pars Intermedia Dysfunction), formerly known as Cushing's Disease, is a hormonal disorder believed to result from age-related changes in the pituitary gland. It's most common in older horses but has been seen in horses as young as five, and it's one of the most common hormonal conditions we see in equine practice. An estimated 21% of horses over age 15 are affected. Because PPID is progressive, catching it earlier gives us more room to manage it well.

  What are the early signs of PPID?

  Early signs can be subtle and are easy to miss. They include:

  • Being prone to infections (skin infections, fevers, cellulitis/lymphangitis — generalized poor immunity)

  • Change in behaviour

  • Inability to maintain weight or muscle, particularly along the topline

  • Lethargy or reduced performance

  • A shaggy or slow-to-shed coat

  • Infertility

  • Fat deposits along the neck crest and elsewhere

  Advanced signs are usually obvious. The subtle, early ones are exactly why testing matters.

• How is PPID diagnosed?

  PPID is confirmed through an ACTH blood test. It's a straightforward on-farm blood draw, and results tell us whether a horse's hormone levels fall outside the normal range for their age and the season. Blood is sent to the lab and within 5-10 days we have results. 

• Why does the time of year matter for testing?

  In the fall, horses with PPID show an exaggerated seasonal rise in ACTH compared to healthy horses. Using seasonally adjusted reference ranges, this makes early or subclinical disease easier to detect in the fall than at other times of year — fall testing can improve the sensitivity and overall accuracy of basal ACTH testing.

  Fall is also a useful time to test more broadly: horses may be carrying extra condition after summer pasture, and knowing metabolic status before exposure to higher-risk fall grass can help us prepare and manage them appropriately, particularly if corticosteroid joint injections are part of their treatment plan.

• Can insulin testing tell us anything more?

  Yes. An insulin test can be added alongside ACTH testing for a more complete assessment of metabolic health, and can identify insulin dysregulation that may not otherwise be apparent. This is worth discussing with us if your horse is carrying extra condition or has a history of laminitis.

• Should my horse be tested?

  If your horse is showing one or more of the early signs above, or if you've simply noticed changes that don't feel like "just getting older," testing is the way to know rather than guess. Reach out and we can talk through whether testing makes sense for your horse.

• How do I get my horse tested?

  Contact us at info@inglemereequine.com and we'll help you figure out next steps.

• Further reading

  For owners who'd like to go deeper, the Equine Endocrinology Group (EEG) publishes consensus recommendations used by veterinarians across the industry:

  EEG Recommendations: PPID (Cushing's Disease)

  EEG Recommendations: EMS and Insulin Dysregulation

• Can metabolic issues affect my horse in ways I wouldn't expect?

  Yes. PPID (Cushing's) can present with a wide variety of clinical signs beyond the classic ones including recurrent and chronic skin infections, cellulitis,  chronic abscesses, chronic pastern dermatitis, difficulty maintaining weight and muscle conditioning, fevers of unknown origin, sinus infections, and laminitis.

  • Insulin resistance can also show up in ways that aren't always expected including horses that are underweight rather than overweight, along with skin issues and increased itchiness related to chronically elevated glucose levels. Chronic pastern dermatitis is also seen in these metabolic patients as well as intermittent and hard to define subtle lameness secondary to foot pain.

    Staying on top of your horse's baseline metabolic status is one of the more effective ways to prevent secondary issues and reduce the likelihood of an emergency down the line.