PPID (Yr 4)

Question 1

what does PPID stand for?

Answer 1

pituitary pars intermedia dysfunction

Question 2

what tiggers the function of the pars intermedia?

Answer 2

neurotransmitters (dopamine)

Question 3

what cells make up the pars intermedia?

Answer 3

melanotrophs

Question 4

what is the main neurotransmitter that acts on the melanotrophs of the pars intermedia?

Answer 4

dopamine

Question 5

what is the overall pathophysiological cause of PPID?

Answer 5

loss of dopamine inhibition on the pars intermedia

Question 6

what is the general effect of dopamine?

Answer 6

inhibitory

Question 7

what does loss of dopamine inhibition mean for the pars intermedia?

Answer 7

excess hormones being produced (ACTH)
hyperplasia or adenomatous change to pars intermedia

Question 8

what is the main hormone produced by the pars intermedia?

Answer 8

ACTH

Question 9

how old do horses develop PPID?

Answer 9

usually >15 years old (rarely less than 10)

Question 10

what is the only predisposing factor for PPID?

Answer 10

age (older than 15)

Question 11

what is the most specific clinical sign of PPID?

Answer 11

hypertrichosis (hirsutism) - delayed/abnormal shedding to thick curly coat

Question 12

what are the clinical signs of PPID?

Answer 12

hypertrichosis (hirsutism)
laminitis
weight loss/redistribution
wasted epaxial muscles and pot belly
bulging supraorbital fat pad
lethargy
sweating
PUPD

Question 13

why is important to confirm PPID with a diagnostic test?

Answer 13

treatment is lifelong/expensive
prognosis
monitor response to therapy
determine if insulin dysregulation is present (poses laminitis risk)

Question 14

what tests can be used to diagnose PPID?

Answer 14

basal ACTH
ACTH response to TRH (rarely used)

Question 15

what are the specific requirements when taking a blood sample for basal ACTH?

Answer 15

don’t do when stressed (after transport)
collect in purple EDTA tube
separate and chill within 3 hours

Question 16

what should be used for the interpretation of a PPID test if the horse has clear clinical signs and is older than 15?

Answer 16

use more sensitive lower values to rule in disease unless below the threshold

Question 17

what should be used for the interpretation of a PPID test if the horse has few clinical signs and isn’t the correct age?

Answer 17

use the upper values to rule PPID out

Question 18

what is the high threshold test used for in PPID?

Answer 18

high specificity (95%) to rule out disease unless above the threshold

Question 19

what is the lower threshold test used for in PPID?

Answer 19

high sensitivity (95%) to rule in disease unless above the threshold

Question 20

if the basal ACTH test comes back inconclusive, what should be done?

Answer 20

retest the horse at a later date, while treating any clinical signs such as laminitis

Question 21

what is the treatment for PPID?

Answer 21

pergolide

Question 22

when a horse is on treatment for PPID, what needs to be done?

Answer 22

baseline endocrine levels (ACTH, insulin, glucose) before starting treatment
document appetite, hair cot, water intake, BCS, laminitis, demeanour
monitor throughout treatment (especially in first month)

Question 23

what is the prognosis for PPID?

Answer 23

lifelong treatment but very successful and they can return to full athletic ability

Question 24

how is hypothyroidism tested for?

Answer 24

TRH stimulation then measure T3 and T4 four to five hours later