An overview and recent insights into Pituitary Pars Intermedia Dysfunction (PPID), or Equine Cushing’s – one of the most common diseases of the endocrine system that can affect horses, as well as Equine Metabolic Syndrome (EMS), a disorder associated with an inability to regulate blood insulin levels. Dr Cristina Rosales BVSc (Hons) MVS MVSc (Clinical) FANZCVS (Eq Med). Equine Medicine Specialist – Scope Equine: Internal Medicine Services.