Adrenal Tumors: Treatment Options

This article discusses potential options for treating adrenal tumors in dogs. Please note, this content is for informational purposes only and does not replace the advice, diagnosis, or treatment of a veterinary professional. We strongly recommend that you contact your veterinarian with any questions or concerns you may have regarding your pet’s medical condition.

Common Treatments

In most cases, treatment for adrenal tumors consists of either surgical removal of the affected gland (adrenalectomy) or medication to control symptoms caused by the tumor. A less common treatment is radiation therapy to shrink the tumor’s size. For malignant tumors, Palladia tablets or chemotherapy could also be treatment options. You can read more about each of these treatments below.

Adrenalectomy: What to Know

An adrenalectomy is a serious and complex surgery. Although it can have a good outcome, removing an adrenal gland is risky. This is because the glands are located next to several major blood vessels, including the vena cava (largest vein in the abdomen), the aorta, and the arteries to the kidneys, an incredibly challenging area to operate in. It’s particularly difficult when the adrenal tumor is large or has invaded blood vessels or other organs.

Dogs who undergo an adrenalectomy are at risk of serious complications both during and after the surgery. The most common, major complications include kidney failure, pancreatitis, hemorrhage, and blood clots to the lungs. The chance of bleeding is higher in dogs with tumors that have invaded the vena cava; the extent of such invasion may not be known prior to the time of surgery.

Adrenalectomy should only be performed by a highly trained and experienced surgeon and at a veterinary hospital capable of rigorously monitoring blood pressure, oxygen, heart activity, and other vital signs. The facility should also be capable of providing intense post-operative care and monitoring.

Following surgery, the veterinarian should conduct an ACTH stimulation test to check whether the remaining adrenal gland is functioning normally. Months or years of cortisol overproduction from the tumor on the removed gland can sometimes cause the normal gland to stop producing cortisol of its own. If the ACTH test shows cortisol is low, the dog will need to take steroid medication until the remaining gland functions normally again, which can take up to six months or longer. It’s essential for the steroid to be given daily, in order to prevent severe and life-threatening cortisol deficiency.

Types of Adrenalectomies

There are two types of adrenalectomies: an open adrenalectomy and a laparoscopic adrenalectomy. For an open adrenalectomy, the surgeon removes the adrenal gland through a large incision along the midline of the dog’s abdomen. This is the preferrable method for large or invasive tumors.

For dogs that have small or medium sized adrenal tumors not invading the vena cava, a laparoscopic adrenalectomy is a potential option. For this procedure, the surgeon makes small incisions in the abdomen and then withdraws the adrenal through one of the small incisions. This type of adrenalectomy is associated with a decreased risk of complications and a shorter recovery time, compared to open adrenalectomy.

Medical Management

For dogs who are not candidates for surgery or whose owners would like a much less invasive approach, medical management may be an option, depending on the type of tumor and other individual factors. These medications are normally given to reduce symptoms, rather than as a cure.

Symptoms of Cushing’s disease, from cortisol-secreting tumors, can usually be controlled with a prescription drug called Vetoryl (trilostane). The active ingredient in Vetoryl is an enzyme inhibitor called trilostane, which blocks the excessive production of cortisol by the adrenal glands.

Lysodren (mitotane) can also be used to treat Cushing’s, but it is prescribed much less commonly than Vetoryl. This drug reduces cortisol levels by eroding the cortisol-producing layers of the adrenal glands. Since some adrenal tumors are resistant to Lysodren, dogs with Cushing’s caused by an adrenal tumor often need a higher dose than dogs with pituitary-dependent Cushing’s disease.

Stereotactic Radiation: A New Approach

Stereotactic Radiation Therapy (SRT) is a type of cancer treatment for humans that has recently made its way into veterinary medicine. The good news is that it can be used for adrenal tumors, including those that are large or tangled with blood vessels. SRT often involves 1-3 sessions of high dose, targeted radiation with the goal of shrinking the tumor. This radiation damages tumor cells while leaving surrounding tissue unharmed.

As with all medical treatments, there are potential side effects to be aware of when your dog is undergoing SRT. Based on animal studies, gastrointestinal issues are common with this treatment and can be severe. There is also potential for altered hormone production—such as changes in cortisol levels— months after treatment. Adrenal insufficiency is a possible late effect and may require hormone monitoring or replacement therapy in some cases.

Palladia (toceranib phosphate)

Palladia is an anticancer medication approved by the FDA for treating mast cells tumors in dogs; however, veterinarians also use it for other types, such as adrenal tumors. It works by cutting off the tumor’s blood supply, which can slow growth or reduce its size. This drug is normally used for pheochromocytomas and other high-risk tumors of the adrenal gland, such as those that are malignant or have metastasized. Palladia comes in tablet form, which pet owners give at home. Dogs on Palladia need to be closely monitored for side effects, which can be serious.

Chemotherapy

For dogs with malignant adrenal tumors, chemotherapy might be an option. The goal of chemotherapy is to stop or slow the growth of rapidly dividing cancer cells, which can prolong the dog’s life. Unlike human medicine, veterinary chemotherapy doses are generally lower and have less side effects.

If you would like more details about any of the treatments discussed in this article, please contact your veterinarian.

References

Adrenal Treatment, by Mar Vista Animal Medical Center

Laparoscopic Adrenalectomy in Dogs, by Arizona Veterinary Center

Adrenal Masses or Tumors, by Veterinary Specialty Center (Illinois)

Adrenal Gland Tumors, by Animal Surgery Center of Michigan

Stereotactic Radiation Therapy for Dogs, by Abby Crownshaw, DVM

Palladia for Dogs, by Julie Ann Hass, DVM