Unit 3 - PPID

Question 1

True or False: Equine PPID is one of the most common diseases of horses, ponies, and donkeys 15 years and older

Answer 1

True

Question 2

What is the average age of PPID?

Answer 2

19-21 but can range from 7-40

Question 3

What is PPID?

Answer 3

Hypertrophy, hyperplasia, or micro/macro-adenoma formation in the pituitary pars intermedia with an increased secretion of POMC peptides

Question 4

In the presence of dopamine, what do D2-type receptors do?

Answer 4

Inhibit POMC mRNA expression and PI POMC-derived hormone release

Question 5

What is critical to the pathology of PPID?

Answer 5

Loss of dopamine inhibition - the concentration of dopamine and its metabolites are decreased 8-fold as compared to age-matched controls

Question 6

Loss of dopamine inhibition is likely due to what condition in PPID?

Answer 6

Loss of functional periventricular dopaminergic neurons

Question 7

PPID is primarily a disease of what origin?

Answer 7

Hypothalamic origin rather than the consequences of a spontaneously forming pituitary adenoma

Question 8

What are the ACTH levels like in PPID patients? Cortisol?

Answer 8

Increased ACTH levels; variable cortisol concentrations

Question 9

What clinical signs are associated with PPID?

Answer 9

Hypertrichosis (hirsutism), muscle atrophy, regional fat accumulation, PU/PD, secondary infections, lethargy, infertility/persistent lactation, exercise intolerance, sweating dysregulation, neurologic, increased appetite, decreased responsiveness to painful stiimuli, and desmitis/tendonitis/tendon and suspensory ligament laxity

Question 10

What is considered to be the pathognomonic sign of PPID?

Answer 10

hirsutism

Question 11

What percentage of PPID cases have concurrent EMS?

Answer 11

30-40% of PPID cases have concurrent EMS

Question 12

What is the ante-mortem diagnosis of PPID?

Answer 12

Testing hypothalamic-pituitary-adrenal axis responsiveness or measurement of endogenous plasma concentrations of POMC-derived peptides (such as ATCH)

Question 13

What are the recommended diagnostic tests for PPID?

Answer 13

TRH stimulation test with ACTH measured (early PPID)

Basal ACTH concentration (Moderate to advanced PPID)

Question 14

What is the procedure for baseline ACTH?

Answer 14

Use glass or plastic tubes containing EDTA
Collect at any time of the day
Keep samples cool at all times
Centrifuge and separate plasma prior to shipping
Ship via overnight mail with ice packs
Samples can be frozen

Question 15

What is the procedure for TRH stimulation test?

Answer 15

Administer 0.5 mg of TRH intravenously. Blood samples are collected in tubes containing EDTA at 0 and 10 minutes after TRH administration

Question 16

When can a TRH stimulation test be done in regards to food?

Answer 16

Horses can be tested after hay is fed, but not within 12 hours after a grain meal.
Can be performed immediately before an OST but do not perform within 12 hours after an OST

Question 17

What clinical signs are associated with TRH stimulation?

Answer 17

coughing, flehmen response, and yawning

Question 18

When is TRH testing not recommended?

Answer 18

In the fall months (between August and October)

Question 19

If TRH testing is done in the fall months, what ACTH level can be used to exclude a diagnosis of PPID?

Answer 19

<110 pg/mL 10 minutes after TRH

Question 20

At what time of the year is baseline ACTH testing preferrable?

Answer 20

Autumn

Question 21

What was previously considered the ‘gold-standard’ ante-mortem test for PPID? The current one?

Answer 21

Previous - Overnight Dexamethasone Suppression Test

Current - ACTH measurement

Question 22

Horses with PPID fail to suppress serum cortisol concentration due to ACTH production from the ______ ________.

Answer 22

Pars intermedia

Question 23

True or False: DST should be avoided in the autumn.

Answer 23

True - this is due to falsw positives

Question 24

What result from the DST is suggestive of PPID?

Answer 24

If the second sample does not suppress below 1 microgram/dl

Question 25

When should resting insulin concentrations be done?

Answer 25

An assessment of insulin regulation should be performed in all horses suspected of having PPID

Question 26

What is the treatment of PPID aimed at?

Answer 26

Improving general health and reducing the risk of disease complications including laminitis and infections

Question 27

What are the appropriate management practices for PPID?

Answer 27

geriatric dietary program, attention to dental and hoof care, and an effective deworming strategy

Question 28

What diet is highly recommended in PPID patients?

Answer 28

Non-structural carbohydrate content

Question 29

How do pharmaceutical interventions for PPID function?

Answer 29

By decreasing the concentrations of circulating POMC peptides to reduce the risk of disease complications
Additional benefits - reduction in the hyperplastic PI size and reduction of adjacent tissue compression

Question 30

What is the preferred drug for treatment of PPID?

Answer 30

Pergolide

Question 31

How often should endocrine testing be done in patients on Pergolide for monitoring purposes?

Answer 31

Every 6-12 months

Question 32

If there is resistance to pergolide, what can be used as an adjunct therapy?

Answer 32

Cyproheptadine

Question 33

What is the initial response (first 30 days) to PPID treatment?

Answer 33

Improved attitude/performance
Increased activity
Improvement in PU/PD
Improved sweating
Decreases in basal ACTH and ACTH 10 minutes post TRH stimulation
Potentially improved glucose and insulin dynamics

Question 34

What is the long-term response to PPID treatment?

Answer 34

Improved hair coat shedding
Increased skeletal muscle along topline
Less pronounced rounding of the abdomen
Less likely to develop infections
Potentially fewer/milder episodes of laminitis

Question 35

How quickly will ACTH concentrations rise post a missed pergolide treatment?

Answer 35

within 48 hours

Question 36

There is a big ole handout at the end of the document that may be helpful to review before the exam.

Answer 36

that is all