Equine PPID

Question 1

describe the pathophysiology of PPID in horses

Answer 1

in the normal physiology: POMC is converted into ACTH and other production by melanotropes, the anterior pituitary (pars intermedia) and dopamine is responsible to inhibiting this breakdown

PPID: degeneration of dopaminergic neurons prevent inhibition of this mechanism, causing overproduction of ACTH and other stuff and hypertrophy of the melanocytes leading to pituitary enlargement

Question 2

Common signalment for PPID

Answer 2

older horses (18-23 yrs)

Question 3

Clinical signs of PPID

Answer 3

1. Hirsuitism/hypertrichosis: long curly coat - 100% of horses with this have PPID
2. weight loss with good appetite
3. regional adiposity
4. muscle atrophy due to excess cortisol/protein catabolism
5. laminitis or recurrent sole abscesses (due to high cortisol +/- hyperinsulinemia)
6. abnormal sweating (increased or decreased)
7. Chronic infections

Question 4

lab findings common with PPID

Answer 4

• hyperglycemia
• hyperinsulinemia
• hypertriglyceridemia
• high fecal egg count

Question 5

what diagnostic test can be used to dx PPID?

Answer 5

1. Basal ACTH
2. TRH stimulation (breaks down POMC)

Question 6

interpreting basal ACTH Testing

Answer 6

• dependent on time of the year
• horses well above the reference range have PPID
• horses in the equivocal grey zone may not- older horses with compatible clinical signs are likely to have PPID, young horses with few or no clinical signs do not

Question 7

Interpreting TRH Stim Test

Answer 7

• baseline ACTH and post- TRH admin ACTH levels measured
• dependent on time of year
• horses well above the reference range have PPID - - horses in the equivocal grey zone may not- older horses with compatible clinical signs are likely to have PPID, young horses with few or no clinical signs do not

Question 8

Treating PPID

Answer 8

• daily admin of dopamine agonist (pergolide)
• recheck ACTH in 30 days

Question 9

Managing PPID

Answer 9

frequent dental care
regular parasite tx
appropriate farrier care to prevent laminitis
weight loss
clip hair in summer