Addison's Disease Secondary to Bilateral Adrenal Gland Metastatic Mammary Carcinoma in a Dog.

A 12 yr old intact female Siberian husky was referred with a 2 wk history of progressive weakness, paraparesis, anorexia, and panting. A 4 cm diameter grade 3 mammary solid carcinoma involving the fifth right mammary gland had been removed 2 days prior to the current visit. While hospitalized, the dog was diagnosed with Addison's disease based on electrolyte disturbances and low serum cortisol levels following adrenocorticotropic hormone stimulation test. An abdominal ultrasound revealed adrenal glands at the upper limit of normal size. Despite treatment, the dog deteriorated and died 4 days after presentation. A postmortem examination revealed a neoplastic infiltrate of epithelial malignant cells in both adrenal glands, popliteal lymph nodes, vertebral bodies, and paralumbar musculature, compatible with metastasis from mammary carcinoma. To our knowledge, this is the first reported case of Addison's disease secondary to metastatic mammary carcinoma in a dog.