| Adrenal Gland Tumors in Cats and Dogs |
| What are adrenal gland tumors? The adrenal glands are small glands buried in fat in the front of each kidney whose function is to regulate the synthesis of important hormones such as cortisol, aldosterone and epinephrine. These hormones interact with many other hormones and influence the function of many organs in the body. Adrenal glands are made up of two major parts, the cortex and the medulla, both of which can develop malignant disease. The adrenal glands are located just atop the kidney Source: www.marvistavet.com/assets/images/adrenal_dog.gif How common are adrenal gland tumors? Based on available data, it is estimated that approximately 0.17%-0.76% dogs (representing 1-2% of all dog tumors) and 0.03% cats (representing 0.2% of all cat tumors) develop primary adrenal gland tumors. Metastasis to the adrenal glands from other organs is uncommon but when it does occur, lymphoma seems to be the most common cancer to spread to adrenal glands. Other cancers that spread to this organ include melanoma, pulmonary carcinoma, histiocytic sarcoma, mammary carcinoma, and hemangiosarcoma. To read about adrenal gland cancer in ferrets, please click here (www. peteducation.com/article.cfm?cls=11&cat=1292&articleid=522) What are the symptoms and how are adrenal gland tumors diagnosed? Abnormalities in adrenal glands can be detected by advanced imaging techniques such as CT and MRI scans or abdominal ultrasounds. Further tests may involve endocrinologic testing, cytology, blood chemistry panel, and imaging of the abdomen and thorax (chest) to rule out cancer in other sites. Adrenocortical tumors Most adrenocortical tumors in dogs and cats are functional but produce increased levels of a hormone called glucocorticoid that lead to Cushing's syndrome. This condition causes changes in the blood glucose levels, electrolyte levels, blood pressure and increases the tendency for blood to clot, leading to an increase in pulmonary embolisms. Some dogs will have only one of the following symptoms, while others may have many:
Adrenal medullary tumors (pheochromocytomas) Adrenal medullary tumors are uncommon in dogs and rare in cats and can be distinguished form adrenocortical tumors by immunohistochemistry. These tumors produce increased levels of catecholamines and are typically diagnosed in older dogs. Their symptoms can be quite nonspecific:
Does cancer cause pain in pets? Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort. To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what cancer pain management options are available for your pet, please visit the Cancer Pain Management section. How important is nutritional support for pets with cancer? Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for example, some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation). Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times, quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please visit the Cancer Nutrition section. How are adrenal gland tumors treated? Treatment of adrenal gland tumors will depend on several factors and must be put in the context of all of the pet's medical problems and overall condition. The treatment options are either surgical removal of the tumor-stricken adrenal gland or administration of drugs to control the clinical symptoms caused by the tumor. The surgery is technically a very difficult one, with many potential complications during and after the procedure. After surgery, animals often need to be supplemented with steroids normally produced by the adrenal gland until the remaining adrenal gland begins to function again. Some pets will require supplementation for life. If surgery is not an option (eg for pets with inoperable tumors or who are very sick and/or old), the adrenal gland tumors can be treated by drugs such as Lysodren or ketoconazole. What are the risks associated with treatment? Risks associated with surgical treatment of adrenocortical tumors Urinary tract infections are extremely common in patients with Cushing's disease and these can lead to postsurgical complications if the stress of the surgery allows the infections to get out of hand. In addition, if only one adrenal gland is affected, the increased production of cortisols from this gland tends to make the other adrenal gland atrophy (waste away), so that it will not function well when the cancerous gland is removed. The greatest postsurgical risks for these tumors are sudden drops in plasma cortisol levels and pulmonary embolism. Other possible surgical complications are hemorrhage during surgery and postoperatively, electrolyte imbalances, pancreatitis from blood clots or manipulation of the pancreas during surgery. Risks associated with surgical treatment of pheochromocytomas Pheochromocytomas also cause disturbances in electrolyte levels, increases in blood pressure (sometimes life threatening with or without surgery) and increased tendency for blood clotting to occur. These tumors will release substances (catecholamines) when manipulated that make all of these problems significantly worse, making them an even greater surgical risk. The major complications with these tumors are severe spikes in blood pressure and pulmonary embolisms. The other complications include pancreatitis, hemorrhage and electrolyTe imbalances. Risks associated with drug treatment of adrenal gland tumors Complications during treatment with Lysodren can include the development of signs due to decreased cortisol production from the adrenal glands. These signs, which can be severe and life-threatening if they go unrecognized, include weakness, lethargy worse than that prior to treatment, loss of appetite, vomiting, diarrhea, and in severe cases, collapse or even shock. The main side effect of ketoconazole is the potential to cause injury to the liver. How do I find a qualified veterinary oncologist? To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your pet's cancer condition, please visit the "Locate a veterinary oncologist" section. Are there any clinical trials evaluating new treatments for adrenal gland tumors in cats and dogs? There are no available clinical trials investigating new treatments specifically for adrenal gland tumors in pets. However, there are several clinical trials available for cats and dogs with any tumor type for which your pet may qualify. To learn more these trials (which are partially or fully funded by the institutions), please visit the Dog Clinical Trials (any tumor type) or Cat Clinical Trials (any tumor type) section. To learn more about veterinary clinical trials in general, please visit the Pet Clinical Trials section. What is the prognosis for pets diagnosed with adrenal gland tumors? Patients without metastatic disease (spread to other organs) often enjoy long-term survival. Approximately 20% of adrenocortical tumors can invade surrounding veins, causing potentially life-threatening intra-abdominal or retroperitoneal (space behind the abdomen) bleeding. Up to 50% of adrenocortical tumors metastasize (spread) to other organs, namely to the liver and lungs. Other organs may include the kidneys, ovaries and thyroid gland. Up to 50% of dogs with pheochromocytomas develop concurrent malignancies. Sources: 1) Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007. 2) www.vetinfo4dogs.com/dadrenaltumor.html 3) www.vet2thepetrx.com/encycEntry.cfm?ENTRY=26&COLLECTION=EncycIllness&MODE=full |
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Last updated 2/19/2017
