PPID

Question 1

PPID is a slowly progressive age-related degenerative disease of what structures?

Answer 1

(Hypothalamic dopaminergic neurons)

Question 2

So we know that PPID is associated with degeneration of the hypothalamic dopaminergic neurons, why does that matter?

Answer 2

(Bc those dopaminergic neurons inhibit the breakdown of POMC (broken down into ACTH most notably) in the pars intermedia, if they go away so does that inhibition)

Question 3

What are some of the clinical abnormalities associated with PPID?

Answer 3

(Hypertrichosis, delayed shedding/hair-coat changes, muscle wasting, laminitis, lethargy, abnormal sweating, PU/PD, tendon/ligament laxity, regional adiposity, recurrent infections/delayed healing, and infertility/abnormal lactation)

Question 4

What PPID test would you reach for in a younger horse with a few signs of PPID?

Answer 4

(TRH stim test)

Question 5

What PPID test would you reach for in an older horse with many signs of PPID?

Answer 5

(Baseline ACTH test; if results not consistent with PPID then reach for a TRH stim test)

Question 6

Describe the procedure for a TRH stim test.

Answer 6

(Make sure grain has not been fed or an oral sugar test performed in the past 12 hours, administer TRH (0.5 mg for <250 kgs and 1.0 mg for > 250 kgs) then immediately collect a blood sample (0 minutes), then collect a 10 minute sample)

Question 7

During what seasons does ACTH tend to be physiologically higher in horses with or without PPID?

Answer 7

(Fall and winter)

Question 8

Why is pergolide the drug of choice for treatment of PPID?

Answer 8

(It is a dopamine agonist so it inhibits the pars intermedia like the degenerate neurons were doing)

Question 9

You are rechecking a horse you diagnosed with PPID 1 month after starting them on 1 mg Prascend, their clinical signs are controlled but their baseline ACTH is still in the PPID likely range, what should you do next?

Answer 9

(Can increase dose or leave it be, suggested to consult with endocrinologist)