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LA DX & TX II > Exam 2 - Equine Endocrine Disorders > Flashcards

Exam 2 - Equine Endocrine Disorders Flashcards

1
Q

what is PPID historically called?

A

equine cushings

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2
Q

PPID generally affects what animals?

A

> 15 years old - geriatric horses

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3
Q

T/F: there is no breed or sex predilection for PPID in horses

A

true

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4
Q

what is the general description on why PPID occurs?

A

loss of dopaminergic inhibitory control of pars intermedia melanotropes

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5
Q

what is the pathophysiology of PPID?

A

loss of dopaminergic inhibitory control in the pars intermedia -> hyperplasia & adenoma formation -> increased melanotrope production -> increased POMC (pro-opiomelanocortin) -> increased peptides, ACTH

body always thinks it is winter time - affects hair coat & fat stores, increase in hormones from august to october

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6
Q

what are some common clinical signs seen in horses with PPID?

A

pathognomic hypertrichosis (especially right behind the elbows in the beginning), loss of top line muscles (sway back), chronic laminitis, suspensory ligament breakdown, hair color changes/patchy shedding

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7
Q

what are some early clinical findings that are supportive of PPID?

A

strongly suggestive - regional hypertrichosis/delayed shedding

suggestive - loss of top line muscles, change in attitude/lethargy, abnormal sweating

possible comorbidities - infertility, tendon/ligament injury, desmitis, laminitis

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8
Q

what are some advanced clinical findings associated with PPID?

A

strongly suggestive - generalized hypertrichosis

suggestive - abnormal sweating, top line muscle atrophy, altered mentation, pu/pd, recurrent infection, rounded abdomen

possible comorbidities - recurrent corneal ulcers, infertility, laminitis, etc

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9
Q

what are some lab findings consistent with PPID?

A

hyperglycemia, hyperinsulinemia, hypertriglyceridemia, & higher fecal egg counts

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10
Q

why is diagnosing PPID sometimes a challenge?

A

no test is perfect

likely miss many horses in the early stages

seasonal effects - so only seen in august through october

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11
Q

how is endogenous ACTH used to diagnose PPID?

A

one EDTA tube - need to spin down samples within 4-8 hours

better to do in the fall - looking for a bigger spike in the horses with PPID because the seasonality of the disease

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12
Q

what components may complicate using an endogenous ACTH test when trying to diagnose PPID?

A

location/climate

season

stress

breed

sedation

type of analyzer used - current is immulite2000XPI which decreases ACTH values

this is why presence of clinical signs is key!!!

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13
Q

how do results of an endogenous ACTH test change with the seasons when trying to diagnose PPID?

A

in winter, (december-june, july, & november), the results to test positive are lower than august-october, so PPID is easier to identify in the fall because of insanely high results

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14
Q

what test are you going to use if you are suspicious of PPID in a geriatric horse with many severe or advanced clinical signs supporting the diagnosis?

A

baseline ACTH & look at insulin status of the animal

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15
Q

what test are you going to use if you are suspicious of PPID in a younger horse with few or mild clinical signs supporting the diagnosis?

A

TRH stimulation test

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16
Q

how is a TRH test done?

A

horse can’t have grain within 12 hours of the test but may have hay - blood is pulled & put in an EDTA tube for a baseline ACTH & then 1 mg (about 1 mL) of TRH is given IV & exactly TEN MINUTES LATER

pull a 2nd blood sample to measure their ACTH

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17
Q

what is the only reason you would use a TRH stimulation test from july to december?

A

only used to identify negative cases in these months due to many false positives

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18
Q

how does season change your interpretation of TRH results?

A

tests run from july-december for TRH tests are only used for identifying NEGATIVE cases of PPID because of the high prevalence of false positives during this time period

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19
Q

what tests are no longer recommended for diagnosing PPID?

A

dex suppression test - risk of laminitis

oral domperidone challenge, ACTH stim, & cortisol

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20
Q

how is an MRI used to diagnose PPID?

A

looks for enlarged pituitary gland - not common

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21
Q

when may the endogenous ACTH test be more sensitive?

A

august through october

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22
Q

what test may be the most sensitive & best for early detection of PPID?

A

TRH stimulation

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23
Q

what is the main side effect associated with pergolide?

A

anorexia

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24
Q

what dosing is used for pergolide?

A

2 mcg/kg PO SID - don’t exceed 4 mcg/kg

25
Q

what drug is used to treat PPID in horses? how is therapy of it used?

A

pergolide

assess clinical signs & endogenous ACTH 1-3 months after starting therapy & then every 6-12 months after

26
Q

what treatment is recommended for refractory cases of PPID?

A

ACVIM consult

cyproheptadine

cabergoline

27
Q

what diet is recommended for horses with PPID?

A

low starch, under 12%

higher fat - beet pulp or rice bran, NO MOLASSES

medium quality grass hay

may have to limit pasture access if concurrent insulin resistance or laminitis

28
Q

what management is recommended for horses with PPID?

A

routine dental care - every 6 months, oral exam & float

FEC monitoring/appropriate deworming

keep up to date on vaccines

good grooming

common sense bio-security

routine shoeing & trimming to prevent foot abscesses

baseline foot rads - check for laminitis

29
Q

what is included in the at risk population for PPID?

A

horses > 10 years old

ponies/horses with previous episodes of laminitis

horses already diagnosed with EMS

30
Q

what should be included in annual wellness checks for geriatric horses/ponies as far as screening for PPID?

A

physical exam, routine bloodwork, PPID testing, & test for insulin resistance

31
Q

what are some risk factors for EMS?

A

middle aged animals

breeds/genetics - ponies, spanish breeds, gaited breeds, morgans, minis, warmbloods, & donkeys

environment/diet - high NSCs & obesity

32
Q

T/F: not every horse with PPID has insulin dysregulation but every horse with EMS does have insulin dysregulation

A

true

33
Q

what components are included in equine metabolic syndrome?

A

hyperinsulinemia!

hyperinsulinemia associated laminitis!

insulin dysregulation!

obesity!

altered adipokines

hypertriglyceridemia

hypertension

PPID

34
Q

why is insulin deficiency a big deal for horses with EMS?

A

in normal animal - insulin is released after a meal to stimulate glucose uptake & stored as glycogen

helps with amino acid uptake, protein synthesis, & fat storage

deficiency - lipolysis (increased free fatty acids, cholesterol, & phospholipids) & protein catabolism

35
Q

why would a horse develop high insulin post-prandial?

A
  1. inappropriately high insulin response to glucose
  2. altered incretin
36
Q

what 3 categories of insulin dysregulation are seen in EMS?

A
  1. basal - resting hyperinsulinemia
  2. post-prandial hyperinsulinemia
  3. tissue insulin resistance
37
Q

why would a horse have basal hyperinsulinemia?

A
  1. increased production
  2. delayed clearance
38
Q

why would a horse have insulin resistance?

A
  1. tissue response failure
  2. chronic insulinemia results in down-regulation of receptors
39
Q

can we see insulin dysregulation without EMS?

A

yes - PPID

horses that are systemically ill, pregnancy, significant stress, & starvation

40
Q

T/F: horses with EMS have a higher risk of developing laminitis

A

true

41
Q

what is the first clinical sign commonly seen in EMS?

A

usually present with laminitis - either acute or chronic (and probably fat)

obesity - regional adiposity, cresty neck, easy keeper, & preputial/mammary enlargement

42
Q

what is seen on the hoof wall? what does this make you suspicious of?

A

divergent growth rings (subclinical or chronic)

EMS

43
Q

what is the preferred test for diagnosing EMS in horses?

A

oral sugar dynamic test

44
Q

how is EMS diagnosed?

A

history & clinical signs

screening tests done stall side - basal insulin & glucose

dynamic tests - preferred is oral sugar test

45
Q

how are screening tests for baseline insulin & glucose done on a horse?

A

can have hay/pasture but no grain for 4 hours prior - blood put into EDTA tube

46
Q

if you get a normal baseline insulin test in a horse, do you rule out EMS?

A

no - more testing

47
Q

what are baseline insulin & glucose tests good for?

A

pre-screening tests, laminitis risks, & ruling out diabetes mellitus

48
Q

what does an oral sugar test evaluate? how is an oral sugar test done?

A

post-prandial insulin response

fast horse for 3-8 hours & then given 0.14 or 0.45ml/kg of karo syrup

collect blood at 60 and/or 90 minutes - measure insulin & glucose

49
Q

what does an insulin tolerance test evaluate? how is it done?

A

insulin sensitivity

non-fasting (can eat whatever)

collect blood at time 0

administer 0.10 IU/kg regular insulin

collect blood at 30 minutes & measure glucose & then immediately feed hay/small amount of grain immediately

50
Q

what insulin tolerance test result is consistent with insulin resistance?

A

<50% decrease in BG from baseline

51
Q

how are horses with EMS managed?

A

diet, exercise, hoof care, medications, & prevention!!!!!

52
Q

how is the diet for a horse with EMS managed?

A

restrict grazing & NSC, <10% NSC, soak hay for 10 minutes, muzzle or slow feeder

nutrient analysis

ration balancer

weight loss calculations - 1.25-1.5% bwt in DM of current weight & reassess bwt & BCS every 30 days

53
Q

________ is CRITICAL for management of a horse with EMS

A

exercise - weight loss & insulin sensitivity

54
Q

how much exercise is recommended for a horse with EMS?

A

at least 30 minutes 3x a week of moderate work - 5x a week is recommended for non-lame horses

55
Q

what is the point of using thyro-l in a horse with EMS? how is it used?

A

use it to stimulate the metabolic rate - improves weight loss & insulin sensitivity

initial dose 0.1mg/kg once daily (48mg/1000lb) & taper once at ideal body weight in 3-6 months - must concurrently decrease food intake & pasture access

56
Q

what is the purpose of using metformin in horses with EMS? how is it used?

A

for persistent hyperinsulinemia - unsure of how it works & not great bioavailability

30mg/kg PO up to TID given 1 hour before feeding or turnout

57
Q

what is the mechanism of action of pergolide?

A

dopamine agonist

58
Q

what is the most appropriate diagnostic tests for the picture of the 24 year old horse?

a. endogenous ACTH + resting insulin
b. dex suppression test
c. endogenous ACTH + OST
d. TRH stimulation test

A

c. endogenous ACTH + OST

test for PPID & concurrent insulin dysregulation/resistance

LA DX & TX II (44 decks)

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