Metastatic tumors to the adrenal glands in domestic animals.

Although metastases to the adrenals are common in humans, they have not been thoroughly studied in animals. The purpose of this retrospective study was to document the types of malignant tumors that metastasize to canine, feline, equine, and bovine adrenals, and the rate at which they do so. The average rate of adrenal involvement in metastatic cancer was 112/534 (21.0%) in dogs, 12/81 (14.8%) in cats, 18/67 (26.9%) in horses, and 5/16 (31.3%) in cattle. In dogs, 26 different tumor types metastasized to the adrenals. Pulmonary, mammary, prostatic, gastric, and pancreatic carcinomas, and melanoma had the highest rates of metastasis to the adrenal glands in dogs. Hemangiosarcoma and melanoma had high rates of adrenal involvement in horses. In cats and cattle, relevant data were only available for lymphoma. Adrenal metastases usually occurred in the late stages of the disease. One dog had developed Addison's disease (hypoadrenocorticism) secondary to lymphoma. Metastatic lesions represented 126/472 (26.7%) of canine, 12/20 (60.0%) of feline, 21/80 (26.3%) of equine, and 5/9 (55.5%) of bovine adrenal neoplasms. This study shows that adrenal glands should be thoroughly examined during both clinical work-up and postmortems when disseminated neoplasia is suspected.