Adrenal disease (Cushings) Flashcards
(43 cards)
List the 4 types of hyperadrenocorticism
Pituitary dependent
Adrenal dependent
Iatrogenic
(ectopic ACTH)
Describe signalment of canine hyperadrenocorticism
middle aged to old dogs
more females than males
List the clinical signs of cushings
PU/PD
polyphagia
Muscle wasting and weakness (pot-belly, panting)
Skin thinning, calcinosis cutis, pigmentation, bruising
Symmetrical hair loss
Reproductive dysfunction
List radiographic finding with cushings
Good contrast
Hepatomegaly
Pot-bellied appearance
Calcinosis cutis
Distended bladder
what do you expect to see on haem with cushings
Stress leukogram:
- Neutrophilia (mature)
- Lymphopaenia
- Monocytosis
- Absolute eosinopaenia
what do you expect to see on biochem with cushings
increased ALP
increased ALT activity
hyperglycaemia
elevated phosphorous
increased cholesterol
mildly abnormal bile acids
what do you expect to see on urinalysis with cushings
Urine specific gravity <1.030 despite often mild dehydration
Mild glucosuria in some cases
Proteinuria in some cases
positive urine culture- due to reduced immune function
List the 4 diagnostic tests for cushings
Low-dose dexamethasone
ACTH response
Urinary cortisol:creatinine ratio
Steroid induced alkaline phosphatase
Describe what happens in pituitary dependent hyperadrenocorticism
the pituitary gland doesn’t respond to the negative feedback stimulated by high cortisol levels
adrenal glands hypertrophy and cortisol levels increase
Describe what happens in adrenal dependent hyperadrenocorticism
excess cortisol produced by the adrenal glands
negative feedback causes reduced GnRH
contralateral adrenal gland atrophies
when should we do cushings test
in a dog that has appropriate clinical signs and some supporting lab results
when should we not do cushings tests and why
in dogs with no supportive clinical signs and lab findings
or
in an ill dog, as we may get false +ves
List 2 tests which we can use to differentiate between pituitary and adrenal hyperadrenocorticism
dexamethasone supression
endogenous ACTH
What is seen if dexamethasone test performed on normal dog
in normal dog= causes suppression of pituitary secretions- cortisol is supressed at 3-8 hours
what happens in a dog with pituitary cushings in the dexamethasone test
There isn’t effective -ve feedback - therefore cortisol only midly reduces at 3 hr mark then back to an increased level at 8 hour mark
what happens with a dog with adrenal cushings in the dexamethsone test
no response in the cortisol level
Describe the ACTH response test
give injection of ACTH, this should cause an increase in cortisol
if the cortisol increases too much, then this indicates hyperadrenocorticism is present
occasionally adrenal tumours can cause a flatline or midrange result
what can cause a low response on the ACTH stim test
exogenous steroid administration
why is the urinary cortisol:creatinine test not often used
it is very prone to stress false positives
Which cushings test is the most sensitive
low dose dexamethaone test
and the UCCR
which cushings test is the most specific (most confidence in positive result)
ACTH stim test
How do we diagnose HAC if we have DM
use non DM clinical signs- hair loss, thin skin, bruising, high insulin requirement
If an animal has HAC and DM which do we treat first
DM
Describe how high dose dexamethasone differentiate adrenal and pituitary HAC
in high dose dex, a suppression of over 50% rules out adrenal source
