Endocrine — Canine

A Na:K ratio below 27 with bradycardia despite hypovolemia in a young female dog suggests hypoadrenocorticism. The ACTH stimulation test showing low pre- and post-cortisol is the confirmatory gold standard. For spontaneous hyperadrenocorticism the LDDST is more sensitive than ACTH stimulation. The urine cortisol to creatinine ratio is only a rule-out screen, and the high-dose test differentiates pituitary from adrenal disease after diagnosis. In diabetic ketoacidosis, fluid deficit and perfusion are corrected first; insulin is started after initial volume restoration and potassium assessment because insulin drives potassium intracellularly and can worsen hypokalemia and hypovolemia. Low total T4 with elevated TSH plus compatible clinical signs confirms primary hypothyroidism. Euthyroid sick syndrome lowers T4 but TSH is typically normal and clinical signs of hypothyroidism are absent.