Canine · Endocrine and metabolic · Internal medicine
Canine hypoadrenocorticism
Young to middle-aged female dog with waxing and waning illness, hyperkalemia, hyponatremia, and a bradycardic shock state that responds dramatically to fluids.
Immune-mediated destruction of the adrenal cortex removes both cortisol and aldosterone in the typical form. Classic findings are a sodium to potassium ratio below 27, absent stress leukogram in a sick dog, azotemia with inadequately concentrated urine, and sometimes hypoglycemia and hypercalcemia. Confirmation is an ACTH stimulation test showing a flat, low cortisol response; endogenous ACTH distinguishes primary from secondary disease. Crisis therapy is aggressive isotonic crystalloid plus dexamethasone, which does not interfere with cortisol assay. Long-term management uses desoxycorticosterone pivalate for mineralocorticoid support plus physiologic prednisone, with owner instruction to increase the glucocorticoid dose during stress.