What are the adrenal glands? And what is the adrenal cortex?The adrenal glands are a pair of glands located above each kidney. The adrenal glands have an outer cortex which is responsible for producing many chemicals (hormones) that influence certain organs and metabolic activities in the body. The inner part of the adrenal gland is called the medulla. The adrenal cortex is responsible for producing the hormone cortisol, the ‘stress’ hormone and is important in body metabolism.
What is an adrenal cortex tumor?An adrenal cortex tumor is an abnormal growth of cells in the adrenal cortex. It can be malignant (adenocarcinoma) or benign (adenoma), but in both cases can cause Cushing’s disease because the tumor can lead to an overproduction of certain body hormones.
What causes this type of tumor?The reason why a particular pet may develop this, or any tumor or cancer, is not straightforward. Very few tumors and cancers have a single known cause. Most seem to be caused by a complex mix of risk factors, some environmental and some genetic or hereditary.
In the case of adenocarcinomas, there are no known causes.
What are the signs of adrenal cortex tumors?Excess production of the adrenal hormones may cause pets to have such signs as increased drinking and urination, hair loss, and a ‘pot-bellied’ appearance. This is due to a condition called Cushing’s disease. Dogs with adrenal cortex tumors often lose their appetite and therefore they lose weight, become weak, listless, and lethargic. Other signs may include calcium deposits in the skin (calcinosis cutis) and muscle wasting. Many dogs only exhibit a few of these signs.
How is this cancer diagnosed?If your pet is exhibiting signs described above, your veterinarian may suspect an adrenal cortex tumor and further evaluation with bloodwork and abdominal ultrasound will help to confirm the diagnosis. Your veterinarian must determine if your pet’s signs are caused by an adrenal cortex tumor or if your pet has pituitary-dependent Cushing’s disease.
In some cases, a tumor (usually adenocarcinoma) will be present on only one of the adrenal glands. In pituitary-dependent disease, since both adrenal glands are stimulated by the pituitary gland, both adrenal glands are usually enlarged.
A CT scan may be recommended are depending on the treatment plan.
How does this cancer typically progress?In most cases, especially in dogs, these tumors are benign. The mass may continue to grow, and your pet may continue to exhibit signs described above. This will be detrimental to the long-term health of your pet. Benign tumors do not spread to other areas of the body.
In the malignant form, the tumor may invade the surrounding tissues and blood vessels. This can lead to severe complications including weakness, development of thrombi (blood clots) in vessels that cut off blood supply and make surgical removal more difficult and complicated. These tumors typically do not metastasize (spread to other locations in the body).
What are the treatments for these types of tumors?The most common treatment for benign forms of this disease is medical (drug) therapy. These therapies are directed at inhibiting the hormone pathways from the pituitary gland to the adrenal glands or against the adrenal gland tissue itself. Given that adenomas are more common than adenocarcinomas, this therapy is appropriate; however, if malignancy is suspected, surgery may be recommended instead of medical therapy.
Prior to surgery, staging (searching for potential spread to other locations in the body) is recommended for malignant tumors. This may include bloodwork, urinalysis, X-rays of the lungs, and possibly an abdominal ultrasound.
Is there anything else I should know?By far the most common tumors that affect pet’s adrenal glands are benign in nature. However, even benign tumors can cause health complications as a result of tumor growth. The sooner a diagnosis and treatment plan can be determined, the better outcome for your pet.

This client information sheet is based on material written by Christopher Pinard, DVM© Copyright 2018 LifeLearn Inc. Used and/or modified with permission under license.