Masses on the adrenal glands are a mystery to most people, including veterinarians. Fortunately, adrenal tumors can be diagnosed and treated, or at least medically managed, most of the time. Nonfunctional adrenal tumors rarely cause harm to, or symptoms in, the affected animal. When a veterinarian sees a dog showing signs consistent with abnormally high secretion of adrenal corticosteroid hormones, she will perform a thorough physical examination of the animal. She will also take a complete history from the dog’s owner about its health, vaccination status, access to potential toxins and access to unvaccinated animals, among a number of other things. The dog’s history and physical examination results will guide the next diagnostic steps.
Most veterinarians evaluating a dog showing non-specific signs that might suggest hyperadrenocorticism will recommend taking blood and urine samples for a complete blood count (CBC), a serum biochemistry panel and a urinalysis. Those results may or may not suggest an adrenal tumor. However, if there is a functional tumor on one or both of the adrenal glands, the test results usually will be abnormal.
Radiographs (X-rays) can be taken to look for any spread (metastasis) of malignant tumors. X-rays can also reveal abnormally sized or shaped abdominal organs and/or enlarged, shrunken or mineralized adrenal glands. An abdominal ultrasound can also help the doctor assess the size and structure of each adrenal gland in greater detail. The veterinarian will be looking for enlargement or irregularity of one of the adrenals and a shrunken or smaller contralateral gland, which would strongly suggest a functional adrenal tumor.
Once a functional tumor is identified, a number of diagnostic tests are available to determine whether mineralocorticoids, glucocorticoids or sex hormones are being secreted by the adrenal cortex. Abdominal computed tomography (CT scan), and/or magnetic resonance imaging (MRI), can be quite helpful to detect any local or remote tissue invasion or spread by a metastatic adrenal mass.
Some adrenal tumors can be biopsied or removed surgically as part of making a definitive diagnosis. The removed tissue will be submitted to a diagnostic laboratory, where it will be analyzed under a microscope. This is the most accurate way to determine whether the tumor is malignant or not.
While arriving at a definitive diagnosis of adrenal tumors can be somewhat time-consuming, almost all of these tumors ultimately can be identified and treated or at least medically managed. There is no easy way to distinguish functional adenomas from adenocarcinomas unless the affected adrenal glands are removed and analyzed by a pathology laboratory. Adenocarcinomas do tend to be a bit larger than adenomas, which sometimes can be detected using radiograph (X-ray) or ultrasound techniques.