Canine Pituitary and Adrenal Diseases & Pheochromocytoma Flashcards
What is the most common cause of Addison’s disease?
primary adrenal faliure due to immune destruction of the adrenal gland
- secondary pituitary failure is rare
What are 2 causes of iatrogenic Addison’s disease?
- prolonged use or high doses of Mitotate or Trilostane
- prolonged use of glucocorticoids causes adrenal atrophy and an abrupt stop without tapering does not allow time for the adrenal gland to adjust
What is the difference between typical and atypical hypoadrenocorticism?
TYPICAL = glucocorticoid AND aldosterone deficient results in hyponatremia and hyperkalemia, usually due to an abnormal adrenal cortex
ATYPICAL = glucocorticoid deficient with normal aldosterone results is normal Na/K, usually due to primary adrenal disease or a decreased in ACTH from the pituitary (aldosterone secreted in response to activation of RAAS, not ACTH)
What is the most common signalment in patients with Addison’s disease? What breeds are predisposed?
mean 4.5 y/o female dogs
- Bearded Collie
- Standard Poodle
- Nova Scotia DTR
- Portuguese Water Dog
- Great DAne
- Westies
- Basset Hounds
What are the most common signs associated with acute onset Addison’s disease?
- bradycardia
- melena
- hematochezia
due to shock to GI
What are the most signs associated with gradual onset Addison’s disease?
- GI: anorexia, vomiting, diarrhea
- lethargic, weak
- PU/PD —> hyponatremia
- collapse
(look like dogs with GI disease)
What are the 4 most common things seen on CBC in patients with Addison’s disease?
- lack of stress leukogram (no cortisol!) - neutrophilia without lymphopenia
- lymphocytosis
- eosinophilia
- mild non-regenerative anemia - GIT bleeding may cause it to become regenerative
What are the 10 most common findings on biochemistry in patients with Addison’s disease? What acid-base abnormality is seen?
- pre-renal azotemia
- hypercalcemia
- hyperkalemia
- hyperphosphatemia
- hypoalbuminemia
- hypochloremia
- hypocholesterolemia
- hypoglycemia - cortisol stimulates gluconeogenesis and glycogenolysis
- hyponatremia
- increased liver enzymes
metabolic acidosis
What is seen on UA in patients with Addison’s? Why is this significant?
< 1.030, minimally concentrated
not concentrated despite pre-renal azotemia (dehydration), due to increased water loss caused by hyponatremia
What imaging can be performed to diagnose Addison’s disease?
- ultrasound: thin adrenals
- thoracic radiographs: microardia, decreased caudal vena cava size due to hypoperfusion
What are 3 other manifestations of Addison’s disease?
- severe GI hemorrhage (cortisol required for health and growth of GI mucosa)
- megaesophagus
- hypoglycemia
What test is used to diagnose Addison’s? What is used for confirmation?
baseline cortisol - >2mg/dL = NOT Addison’s; <2mg/dL = COULD be Addison’s
ACTH stim - pre and post <1
What is recommended for Addison’s disease treatment?
- glucocorticoid replacement
- mineralocorticoid replacement
What 2 options are available for glucocorticoid replacement for Addison’s disease treatment?
- injectable Dexamethasone - doesn’t cross-react with assay, can be given to crashing patients before diagnosis, may be needed for patients that cannot take pills
- Prednisone - can cause false negatives of ACTH stim
What 2 options are available for mineralocorticoid replacement for Addison’s disease treatment?
- Fludrocortisone (Florinef) - daily, oral
- Desoxycortisoterone pivalate (DOCP) - monthly injectable
