Pheochromocytoma in Cats

 

A pheochromocytoma is a type of adrenal gland tumor which causes the gland to make too much of some of the hormones. This can cause an increase in heart rate, blood pressure, and breathing rate. These symptoms are intermittent (not present all of the time) because the hormones that cause them are not made all of the time or are made in low amounts.

 

Pheochromocytomas are rare in cats. When they do occur it is usually with older cats. Because this tumor affects an endocrine gland that functions to spread hormones, pheochromocytomas commonly spread to organs that are near them and can rapidly metastasize to other areas of the body.

 

Symptoms and Types

 

• Weakness
• Shaking
• Collapse
• Lack of appetite (anorexia)
• Lack of energy (lethargy)
• Lack of interest in usual activities (depression)
• Vomiting
• Panting
• Rapid breathing (tachypnea)
• Increased urination (polyuria)
• Increased thirst (polydipsia)
• Diarrhea
• Weight loss
• Pacing
• Seizures
• Bloated abdomen
• Symptoms may seem to come and go
• Occasionally no symptoms will be present

 

Causes

 

Pheochromocytoma is labeled idiopathic, since there is no known cause for this condition.

 

Diagnosis

 

Your veterinarian will need a thorough medical history and time-line of your cat's behavior, health and onset of symptoms. Your veterinarian will palpate your cat's belly to see if a mass can be felt or if there is extra fluid is present. A rapid heart rate (tachycardia) is sometimes found during the physical examination, but sometimes, there will not be anything that appears to be abnormal during the examination. Standard blood work, including a complete blood count, biochemical profile and urinalysis will be ordered. These will indicate how well your cat's internal organs are working and whether there are any infections present. Your veterinarian may also order a special blood test which will indicate whether the adrenal gland is functioning normally. Your cat's blood pressure will be taken, and in some cases, the blood pressure will be very high, indicating hypertension.

 

 

If your cat's heart rate is very high, or its heart seems to have an abnormal rhythm, your veterinarian may order an electrocardiogram (ECG) to check the electrical capability of the heart. Your veterinarian will also order x-rays and/or ultrasound images of your cat's abdomen and thorax (chest). If there are abnormalities of the internal organs, they may show up on an x-ray or ultrasound image. Further diagnostic tests may include a computed tomography (CT) scan or magnetic resonance image (MRI). These imaging tools are higher sensitivity tests, which can give a more detailed picture of your cat's internal organs. To confirm a final diagnosis, your veterinarian will need to take a biopsy of the adrenal gland for laboratory analysis.

 

It is common for cats with a pheochromocytoma to have more than one medical problem, and treatment will be approached according to which condition is most critical.

 

Treatment

 

Surgery is the chosen treatment for a pheochromocytoma. If your cat has high blood pressure or a very high heart rate, these conditions will be treated with medication and stabilized before surgery can be performed. If the blood pressure or heart rate are dangerously high, your cat may need to be in intensive care before surgery can be performed. Some cats need to be placed on medication to control blood pressure and heart rate for several weeks before surgery can be performed.

 

During surgery, the affected adrenal gland will be removed. Because the adrenal gland is near some very large blood vessels, surgery can be challenging. If, during surgery, it is found that other organs are being affected by the tumor, they will need to be removed as well, either in part or in their entirety, depending on the organ. After surgery, your cat will be kept in the hospital intensive care unit until it is stable. Problems during and after surgery are common. Your veterinarian will monitor for bleeding, high or low blood pressure, abnormal heart rhythm, difficulty breathing, or post-operative infections. Unfortunately, some cats do not make it through recovery because of these problems, especially if they have other medical problems. Your veterinarian will help you to decide the best course of action based on the diagnosis and expectations for recovery.

 

Living and Management

 

Once your cat's tumor has been removed and it is able to return home with you, it will take a little time for your cat to return to a normal life with normal activity. Your cat's life expectancy will be based on whether there are other health conditions concurrent with the pheochromocytoma. Some cats will continue to live for three or more years, while others have shorter expectancies.