Adrenal Gland Cancer in Cats

The growth of a tumor, caused by an accumulation of cells that rapidly multiply in one location, can result in adrenal gland cancer. Adrenal gland cancer can affect both layers of the adrenal gland; the adrenal medulla or the adrenal cortex. However, adrenal cancer masses are aggressive in nature and can quickly spread to the cat’s spleen, kidneys, lungs or liver, due to the rich blood supply of these glands. Although quite rare in felines, adrenal gland cancer can be fatal and will quickly spread to surrounding organs if not timely addressed by a veterinary professional. 

The adrenal glands are paired, peanut-shaped glands buried in fat in front of each kidney. These glands function to regulate the synthesis of about 30 different hormones that are vital in maintaining bodily functions. Specifically, the adrenal glands control the sex hormones, help regulate the immune system, maintain a balance of carbohydrates, salt and water, as well as aid in blood pressure control for the feline. When a tumor forms in one or both of these adrenal glands, every bodily function that these glands regulate are compromised. 

The clinical signs of adrenal gland cancer in cats depends on the type of cancer as well as the location of the adrenal tumor. An abnormal growth of cells in the adrenal gland will cause the gland to secrete more hormones that what the body needs, therefore, clinical signs of this cancer will also depend on the hormone that is being produced in excess. Due to the amount of hormones that adrenal glands produce and the different functions stimulated by the release of said hormones, the symptoms of adrenal gland cancer in cats can occur intermittently. Common symptoms a cat owner may notice at home include: 

• Swelling of the limbs
• Racing heart rate
• High blood pressure
• Collapse 
• Trembling 
• Weakness
• Extended abdomen 
• Tiredness 
• Polyuria 
• Polydipsia 
• Hair loss (alopecia) 
• Panting 
• Anorexia 
• Muscle wasting 
• Thin skin

Types 

There are three main types of tumors that affect the adrenal glands in cats including: 

• Pheochromocytoma
• Adrenocortical carcinomas 
• Adrenocortical adenomas

Tumors of the adrenal glands can be either hyperplasia (non-cancerous), benign (non-spreading) or malignant (aggressively spreading). Pheochromocytomas tend to spread from the adrenal glands vein to the vena cava, whereas malignant tumors can spread to the kidneys, pancreas, and liver. 

The cause of adrenal gland cancer in cat remains unknown to veterinary medicine. However, in human medicine, adrenal cancer has been linked to genetic predispositions of a person’s DNA. Researchers have not found a genetic link to adrenal cancer in cats and are still looking for evidence of an underlying cause to this disease.

The diagnosis of adrenal gland cancer in cats will begin with a physical examination of the affected feline and a review of the cat’s medical history. The veterinarian may ask pet owners questions about current medications, diet and a time frame of the presenting symptoms. The veterinarian may then request specialized screening imaging such as an ultrasound or radiograph to confirm the presence of a tumor. However, the adrenal glands are small and not easily seen on an x-ray, therefore, advanced imaging techniques such as an MRI or CT are better diagnostic tools. Further testing may include a blood chemistry profile, cytology (examination of the cancerous nature of a tumor), endocrinologic testing, followed by imaging of the feline’s thorax and abdomen. 

Your veterinarian may prescribe beta blockers and amlodipine to combat associated symptoms of high blood pressure, as well as racing heart rate. 

Unlike other types of cancer, adrenal gland cancer does not respond well to chemotherapy. Adrenal gland cancer in cats can be treated by surgical removal of the tumor or managed medically. Surgical removal of the adrenal mass possess a risk of hemorrhage and handling the adrenal glands can cause a sudden release of adrenal hormones, causing anesthetic complications. Due to concerns in surgical removal, your veterinarian may refer your cat to a specialty clinic with intensive care accommodations.

Felines who have received treatment for their adrenal gland cancer without metastatic disease (spreading to other organs) have a positive prognosis and long-term survival. Due to the aggressive nature of this disease, up to 50 percent of these adrenal tumors spread to surrounding organs and 20 percent spread to the veins. In the case of metastatic adrenal gland cancer, the prognosis for the affected feline is rather grave.