Hyperadrenocorticism

Question 1

What are the three types of hyperadrenocorticism?

Answer 1

(Pituitary dependent, adrenal dependent, and iatrogenic)

Question 2

What changes in the liver values do you expect to see on a chem of a dog with suspected Cushing’s disease?

Answer 2

(ALT can be normal to increased; ALP must be increased (since it has a cortisol isoenzyme, if ALP is not increased that will push Cushing’s lower on your differential list))

Question 3

Do you expect a Cushingoid dog to have a dilute or concentrated (choose one) USG?

Answer 3

(Dilute, typically less than <1.020)

Question 4

What is the purpose of the urine cortisol:creatinine ratio test?

Answer 4

(To rule out HAC → this test can tell you ‘this dog does not have HAC’ but it cannot tell you ‘this dog has HAC’ (so it is highly sensitive but unspecific))

Question 5

If Cushing’s is high on your differential list (as in the dog has clinical signs that make you suspicious of HAC), which of the HAC screening tests would you reach for?

Answer 5

(Low dose dexamethasone suppression test/LDDST or the ACTH stimulation test)

Question 6

How do you tell the difference between pituitary or adrenal-dependent HAC via ultrasound?

Answer 6

(With pituitary-dependent, adrenal glands will be symmetrical; with adrenal-dependent, one adrenal gland will have a mass and the other will be small)

Question 7

What HAC screening test can be used to potentially differentiate between pituitary and adrenal-dependent HAC?

Answer 7

(LDDST, the presentation of the curve can possibly differentiate between PDH and ADH but not always)

Question 8

What additional test can be used to differentiate between PDH and ADH, besides ultrasound and a LDDST?

Answer 8

(Endogenous ACTH/eACTH concentration → if within or above the reference range it indicates PDH, if it is lower than the reference range it indicates ADH)

Question 9

What drug is used to treat both pituitary and adrenal-dependent HAC, when surgery is not an option?

Answer 9

(Trilostane → suppresses cortisol production in the adrenal gland)

Question 10

If you are presented with a patient with a lack of suppression curve from a LDDST, what two further diagnostics would facilitate differentiation between pituitary or adrenal dependent cushings?

Answer 10

(Endogenous ACTH and abdominal ultrasound)

Question 11

What value do you expect to see on an endogenous ACTH test if your patient is pituitary dependent?

Answer 11

(A value normal or higher than the reference interval)

Question 12

What value do you expect to see on an endogenous ACTH test if your patient is adrenal dependent?

Answer 12

(A value less than the reference interval bc the cortisol produced by the adrenals is telling the pituitary to stop making ACTH)

Question 13

What LDDST curve pattern are you looking for if you are looking for pituitary dependent cushings?

Answer 13

(A partial suppression curve which means at some point either the 4-hour, 8-hour or both values went below the 50% of the 0-hour value line but was still above the reference range)

Question 14

What is the recommended starting dose and frequency of trilostane?

Answer 14

(1-2 mg/kg q12, give with food)

Question 15

What is the monitoring test of choice for cushings being treated medically?

Answer 15

(ACTH stim test)

Question 16

What is the goal in medical treatment of cushings?

Answer 16

(A post-ACTH cortisol value of 1.5-5.5 mcg/dL with control of clinical signs)

Question 17

Give the three gold standard times ACTH stim tests should be run in a patient newly placed on trilostane and what you are looking for at each visit.

Answer 17

(2 weeks after diagnosis to make sure you are not making the dog addisonian, 4 weeks after diagnosis to make sure the animal is controlled (which means no clinical signs), and 2 weeks after any dose changes are made to again check for control of the dz)

Question 18

Is the LDDST sensitive or specific and why does that matter?

Answer 18

(The LDDST is sensitive which means it has very few false negatives so you can trust ‘negative = animal doesn’t have cushings’, it is not specific so it can have false positives so that is why you should only run it on animals with clinical signs)