Factors associated with survival, laminitis and insulin dysregulation in horses diagnosed with equine pituitary pars intermedia dysfunction.
Authors: Horn R, Bamford N J, Afonso T, Sutherland M, Buckerfield J, Tan R H H, Secombe C J, Stewart A J, Bertin F R
Journal: Equine veterinary journal
Summary
# Editorial Summary: PPID in Australian Horses—Latitude, Laminitis and Insulin Dysregulation Equine pituitary pars intermedia dysfunction (PPID) affects older horses worldwide, yet most clinical data comes from Northern hemisphere populations where the disease presents predictably with classic signs like hirsutism and weight loss. Horn and colleagues examined 274 horses and ponies across eight Australian sites to characterise how PPID manifests at different latitudes and identify risk factors for survival, laminitis and insulin dysregulation (ID). Diagnosis relied on endogenous ACTH measurement, dexamethasone suppression, TRH stimulation or post-mortem findings, with laminitis confirmed radiographically and ID assessed via fasting insulin, oral glucose tolerance or two-step insulin response testing. The study found that nearly 90% of diagnosed horses developed laminitis and 76.5% showed evidence of ID, with clinical presentation varying markedly by latitude—lower latitudes showed higher rates of anhidrosis and polyuria/polydipsia rather than the expected coat changes. Ponies, horses maintaining higher body condition scores and those receiving pergolide therapy had significantly better survival outcomes, suggesting that aggressive weight management and early dopamine agonist treatment are critical management strategies. Although limitations in uniform diagnostic protocols across referral and primary-care sites reduce statistical power, these findings highlight that PPID should prompt systematic screening for ID regardless of latitude, and that maintaining condition whilst treating the underlying endocrinopathy remains fundamental to improving long-term prognosis.
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Practical Takeaways
- •Insulin dysregulation should be routinely investigated in all equids diagnosed with PPID, as it was present in over three-quarters of cases tested
- •Maintaining adequate body condition and consistent pergolide administration are fundamental management strategies for improving survival in PPID cases
- •PPID clinical signs vary geographically; clinicians in lower-latitude regions should specifically monitor for anhidrosis and increased drinking/urination alongside traditional PPID presentations
Key Findings
- •Laminitis was diagnosed in 89.9% of PPID cases investigated, and insulin dysregulation in 76.5% of cases
- •Ponies, horses with higher body condition scores, and those receiving pergolide had better survival rates
- •Clinical presentation of PPID varied by latitude and climate, with anhidrosis and polyuria/polydipsia more common at lower latitudes