The clinical findings seen in dogs with hypoadrenocorticism are vague and nonspecific, and it takes a high index of suspicion to diagnose the disease. Lethargy, anorexia, vomiting, weakness, and waxing and waning disease that responds to therapy are often reported. Dogs are typically hyperkalemic, hyponatremic, azotemic, acidotic and do not have a stress leukogram. Definitive diagnosis is based on an inadequate adrenal reserve with a corticotropin-stimulation test. Treatment requires giving the appropriate mineralocorticoid and/or glucocorticoid replacement. An addisonian crisis is a medical emergency and requires immediate treatment. Aggressive therapy may not be needed in all cases, but lifelong maintenance with corticoid replacement therapy will be necessary. Desoxycorticosterone pivalate can be given at a dose of 2.2 mg/kg SC or IM at 1-month intervals. Electrolytes are monitored to determine duration of action and whether dosages need to be adjusted. Fludrocortisone is used at an initial dosage of 0.01 to 0.02 mg/kg/day and adjusted by increments. About 50% of dogs will need daily prednisone (0.2 mg/kg/day).

COMMENTARY: This paper, "Unmasking the Imposter," is aptly titled, because hypoadrenocorticism is often not the first on a diagnostic rule-out list. Diagnosing the disease early allows therapy to be instituted before a crisis situation develops.

Unmasking the imposter: Diagnosis and treatment of canine hypoadrenocorticism. Kintzer PP. ACVIM PROC, 2004, 459-461.