Feline Hyperadrenocorticism Flashcards
What’s the prognosis of feline HAC compared to the dog?
worse
What’s the most common form of feline HAC?
85% = PDH, the remainder = ADH (adrenal dependent hyperadrenocorticism)
What are some common dermatological changes with feline HAC?
- skin hyperfragility – watch for tears!
- skin infections (bacterial, fungal)
- symmetrical, truncal & abdominal alopecia, non pruritic
- Calcinosis cutis = NOT a thing in cats
What are some metabolic changes noted in feline HAC?
- PU/PD/PP: due to glucocorticoid diabetogenic effects
- concomitant CKD (not a thing in dogs)
- if not diabetic or have CKD, then NO PU/PD
- can have weight loss (minor) or weight gain
What are some PE changes for feline HAC?
- poor haircoat
- pendulous abdomen
- generalized muscle wasting
- weight gain
What are some concurrent illness that cats with HAC can also have?
- diabetes mellitus. Typically insulin resistant
- frequent, resistant/ hard to resolve infections - a combination of immunosuppression, skin fragility, and concurrent illness
- CKD - no causation between CKD and HAC. Cats with USG < 1.020 likely have concurrent CKD
- Pancreatitis
- Hypertension
What is the most common blood work abnormalities noted for feline HAC?
about 80% = hyperglycemic, even those that don’t have overt diabetes mellitus
What biochemistry changes are noted with feline HAC?
- hyperglycemia
- hypercholesterolemia (poor controlled diabetes and increased lipolysis)
- increased BUN (>50%)
- increased BUN and creatinine (>25%)
- cats don’t get steroid induced ALP, so only a mild increase in noted (likely from diabetes, such for ALT increase)
What are some CBC changes noted with cats with HAC?
Occur in consistently
- lymphopenia
- neutrophilia
- eosinophilia
Is USG > 1.020 possible for feline HAC?
yes, the non-diabetic ones can still concentrate urine
Overall how does the blood work abnormalities for cat differ from the dog with HAC?
- cat bloodwork = less profound vs the dog
- but, cat’s PE is more dramatic
What’s the utility of abdominal x-rays for cats with HAC?
always need to correlate imaging findings with c/s as presence of mass does NOT equal function’
- increased abdominal enhances abdominal imaging
- but only a small number of cats have visible adrenal mass
- survey rads (chest and abdomen) can help to identify concurrent illness, which may influence treatment/ prognosis
- adrenal mineralization can be an incidental old-age finding in cats
What’s the utility of AUS for cats with HAC?
- experienced ultrasonographer can identify the adrenal glands in healthy cats
- challenge in differentiating between hyperplastic vs normal
- malignant ones tend to have vascular invasion
- if an adrenal mass is noted, should check the liver and spleen for metastasis
What’s the utility of CT/MRI for cats with HAC?
- useful in the diagnosis of adrenal hyperplasia, adrenal tumour, and pituitary tumour
- can assess for vascular invasion, which can help with adrenalectomy planning
- correlation of pituitary tumour size and presence of neurological signs is not clear
Is basal cortisol test effective for feline HAC?
No, basal cortisol value is not useful for assessment of adrenal function in cats
What’s the diagnostic value of ACTH stim test for cats with HAC?
- sensitivity = 56-80%
- DDX = feline hyperthyroidism (for increased post ACTH stim cortisol)
- cats tend to have less dramatic response compared to the dog
- peak timing and magnitude is variable
- typically test 60 & 90min post ACTH
What’s the diagnostic value of dexamethasone suppression test for cats with HAC?
- the “low dose” for cat = “high dose” for dogs
- it’s a good initial screening tool to rule in HAC
- could possibly aid in ADH vs PDH (PDH will suppress at 8h)
- if the cat suppresses with low dose but has clinical signs consistent with HAC, can try a “dog low dose” (0.01mg/kg vs 0.1mg/kg)
What’s the diagnostic value of UCCR for cats with HAC?
- it’s a good screening (sensitivity) but has poor specificity (ex. feline hyperthyroidism also can have increased UCCR)
What’s the treatment for ADH in cats?
Adrenalectomy
- will need imaging to assess for possible invasion into major blood vessels or kidneys
- post-op hypoadrenocorticism = common
- will need fludrocortisone supplementation long term; prednisolone can usually be tapered overtime
- will help with glycemic control/ insulin dose
What are the surgical options for PDH in cats?
- trans-sphenoidal hypophysectomy & bilateral adrenalectomy
- will require lifelong supplementation (fludrocortisone and prednisolone) and treatment for diabetes insipidus
What’s the utility of trilostane for cats with HAC?
Trilostane = competitive inhibition of 3-beta hydroxysteroid dehydrogenase
- can be effective, though no PK studies done
- manufacturer does NOT recommend its use in patients with hepatic or renal compromise
- side effects: lethargy, anorexia, hyponatremia, hyperkalemia
- no published data on monitoring
- initially though ACTH stim, but it is unreliable
- best to base on history and PE findings
What are some other medical therapy options for feline HAC?
Mitotane
- well tolerated by cats
- however, frequently ineffective at controlling c/s
Metyrapone
- inhibits 11 beta-hydroxylase, used in conversion to cortisol
- it’s at least transiently effective
Ketoconazole
- ineffective in cats
- can inhibit steroid production in dogs and people
What’s the role of radiation therapy in PDH cats?
- can resolve neurological and (some) endocrine signs
- improve glycemic control in acromegaly, unsure about HAC
What’s the prognosis of feline hyperadrenocorticism?
poor if untreated or unresponsive to treatment
- die of severe infection, or uncontrollable diabetes mellitus
With appropriate treatment, can have good to excellent outcome.
