Efficacy of pergolide for the management of equine pituitary pars intermedia dysfunction: A systematic review.
Authors: Tatum R C, McGowan C M, Ireland J L
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Pergolide Efficacy in PPID Management Pergolide, a dopamine agonist widely used to treat pituitary pars intermedia dysfunction (PPID) in aged horses, lacks robust clinical evidence despite decades of clinical application—a gap that prompted this systematic review of published literature between 1997 and 2020. Tatum, McGowan and Ireland screened 612 publications, ultimately including 28 studies (predominantly descriptive case series and uncontrolled field trials) that examined whether pergolide improved clinical signs or adrenocorticotrophic hormone (ACTH) concentrations. Across the included studies, over 75% of treated horses showed overall clinical improvement; however, individual clinical sign responses varied considerably, and plasma ACTH reductions occurred in only 44–74% of cases, with normalisation to reference intervals achieved in just 28–74%. The marked heterogeneity in study design, pergolide dosing protocols, diagnostic criteria and follow-up periods precluded meta-analysis, highlighting the weakness of the existing evidence base. Practitioners should recognise that whilst pergolide remains a reasonable treatment option for PPID, the variable endocrine and clinical responses observed across cases underscore the need for individualised monitoring and the importance of well-designed, controlled clinical trials to establish optimal dosing strategies and identify horses most likely to respond.
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Practical Takeaways
- •Pergolide demonstrates clinical efficacy in managing PPID in most cases, but individual response to treatment is variable and unpredictable
- •ACTH normalisation occurs in less than three-quarters of treated horses; biochemical response does not always accompany clinical improvement, so both parameters should be monitored
- •Limited high-quality evidence exists; practitioners should manage client expectations about efficacy and the need for individualised monitoring protocols including both clinical assessment and endocrine testing
Key Findings
- •Pergolide provided overall clinical improvement in >75% of cases across most included studies despite significant variation in study design and protocols
- •Plasma ACTH concentration reduction was reported in 44-74% of cases, with normalisation to reference intervals occurring in 28-74% of cases
- •Improvements in individual clinical signs varied widely across studies, and meta-analysis could not be performed due to marked between-study variations
- •Most included studies were descriptive case series, cohort studies, or non-randomised uncontrolled field trials with heterogeneous outcome measures