Unit 3 - PPID Flashcards
True or False: Equine PPID is one of the most common diseases of horses, ponies, and donkeys 15 years and older
True
What is the average age of PPID?
19-21 but can range from 7-40
What is PPID?
Hypertrophy, hyperplasia, or micro/macro-adenoma formation in the pituitary pars intermedia with an increased secretion of POMC peptides
In the presence of dopamine, what do D2-type receptors do?
Inhibit POMC mRNA expression and PI POMC-derived hormone release
What is critical to the pathology of PPID?
Loss of dopamine inhibition - the concentration of dopamine and its metabolites are decreased 8-fold as compared to age-matched controls
Loss of dopamine inhibition is likely due to what condition in PPID?
Loss of functional periventricular dopaminergic neurons
PPID is primarily a disease of what origin?
Hypothalamic origin rather than the consequences of a spontaneously forming pituitary adenoma
What are the ACTH levels like in PPID patients? Cortisol?
Increased ACTH levels; variable cortisol concentrations
What clinical signs are associated with PPID?
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
What is considered to be the pathognomonic sign of PPID?
hirsutism
What percentage of PPID cases have concurrent EMS?
30-40% of PPID cases have concurrent EMS
What is the ante-mortem diagnosis of PPID?
Testing hypothalamic-pituitary-adrenal axis responsiveness or measurement of endogenous plasma concentrations of POMC-derived peptides (such as ATCH)
What are the recommended diagnostic tests for PPID?
TRH stimulation test with ACTH measured (early PPID)
Basal ACTH concentration (Moderate to advanced PPID)
What is the procedure for baseline ACTH?
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
What is the procedure for TRH stimulation test?
Administer 0.5 mg of TRH intravenously. Blood samples are collected in tubes containing EDTA at 0 and 10 minutes after TRH administration
When can a TRH stimulation test be done in regards to food?
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
What clinical signs are associated with TRH stimulation?
coughing, flehmen response, and yawning
When is TRH testing not recommended?
In the fall months (between August and October)
If TRH testing is done in the fall months, what ACTH level can be used to exclude a diagnosis of PPID?
<110 pg/mL 10 minutes after TRH
At what time of the year is baseline ACTH testing preferrable?
Autumn
What was previously considered the ‘gold-standard’ ante-mortem test for PPID? The current one?
Previous - Overnight Dexamethasone Suppression Test
Current - ACTH measurement
Horses with PPID fail to suppress serum cortisol concentration due to ACTH production from the ______ ________.
Pars intermedia
True or False: DST should be avoided in the autumn.
True - this is due to falsw positives
What result from the DST is suggestive of PPID?
If the second sample does not suppress below 1 microgram/dl
When should resting insulin concentrations be done?
An assessment of insulin regulation should be performed in all horses suspected of having PPID
What is the treatment of PPID aimed at?
Improving general health and reducing the risk of disease complications including laminitis and infections
What are the appropriate management practices for PPID?
geriatric dietary program, attention to dental and hoof care, and an effective deworming strategy
What diet is highly recommended in PPID patients?
Non-structural carbohydrate content
How do pharmaceutical interventions for PPID function?
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
What is the preferred drug for treatment of PPID?
Pergolide
How often should endocrine testing be done in patients on Pergolide for monitoring purposes?
Every 6-12 months
If there is resistance to pergolide, what can be used as an adjunct therapy?
Cyproheptadine
What is the initial response (first 30 days) to PPID treatment?
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
What is the long-term response to PPID treatment?
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
How quickly will ACTH concentrations rise post a missed pergolide treatment?
within 48 hours
There is a big ole handout at the end of the document that may be helpful to review before the exam.
that is all
