Endocrine2- PPID

  1. What is the primary neuroregulatory input to the pars intermedia?
    paraventricular nucleus
  2. What is the pathophysiology of PPID?
    dopaminergic neurodegeneration of the paraventricular nucleus--> less dopamine, which is inhibitory to PI--> hyperplasia of PI and excess secretion of hormones
  3. Describe POMC metabolism in the pars intermedia.
    POMC is cleaved to ACTH and α-MSH (which is specific to the PI), endorphins also secreted from PI
  4. The pars intermedia has increased function in the _________, even in normal horses; the implication of this is...
    fall; test eACTH in fall in suspect PPID horses--> levels will be astronomically high--> easy to Dx PPID with seasonally-corrected reference interval
  5. Clinical signs of PPID.
    hypertrichosis** due to delayed shedding and retention of guard hairs, muscle atrophy/weight loss**, abnormal fat deposition, laminitis**, secondary infections**, PU/PD, insulin resistance, hyperhidrosis (sweating), docility (endorphins)
  6. Where is regional adiposity common in PPID horses?
    nuchal ligament, tail head, supraorbital fossae
  7. When is the peak incidence of laminitis in PPID horses vs non-PPID horses?
    • PPID: September
    • non-PPID: May
  8. What is an injury that should prompt you to test for PPID, even if it is the only complaint/sign?
    indolent corneal ulcer- won't heal
  9. What is the gold standard for diagnosing PPID?
    histopathology of the pars intermedia- not a very good test tho
  10. What is the recommendation for diagnosing PPID?
    use multiple diagnostic tests in any one clinical case, as even in very chronic disease, one frequently gives a negative/ambiguous result
  11. What are ante-mortem tests use to diagnose PPID, and what time of year is each usually given?
    eACTH (fall), 19hr dexamethasone suppression test (spring), TRH stimulation test
  12. Describe the dexamethasone suppression test as used in horses to diagnose PPID.
    Dex then measure cortisol 19 hours later; should suppress cortisol <1mg/mL (failure to suppress suggests PPID)
  13. Describe the TRH stimulation test.
    measure ACTH in plasma collected 10 and 30 min after TRH IV
  14. What is the treatment for PPID?
    Pergolide (Prascend)- dopaminergic agonist
Card Set
Endocrine2- PPID
vetmed endocrine2