Adrenal Biopsy in Cats

An adrenal biopsy is a surgical procedure used for diagnostic purposes. It is a common practice used throughout the medical community, often paired with diagnostic imaging. Because of this, it is generally performed by a veterinarian with interventional radiology training. An adrenal biopsy is used to identify the composition of abnormal masses or lesions located on either of the two adrenal glands. It is a relatively safe procedure that is performed if diagnostic imaging alone has been unable to identify the type of growth present. This procedure may end the diagnostic process and help formulate the proper treatment plan for the cat. 

Before a cat undergoes an adrenal biopsy, first the masses on the glands need to be detected and located. The first indication of an adrenal abnormality may show up on a routine complete blood count test (CBC). If hormone levels are unusual, an ACTH stimulation test will then be performed to see how the gland reacts. If both of these tests have rendered results that are not average, the cat will need diagnostic imaging. This is usually done with an ultrasound, but may be completed using a CT scan or an MRI if available. 

If diagnostic imaging proves to be unsuccessful at determining the type of growth that exists on the adrenal gland, the next step will be for the veterinarian to determine if the tumor location allows a safe path for a biopsy to be completed. If the benefit to the cat outweighs the potential risk of complications, a date will be booked for the procedure to be performed. The cat will require general anesthesia for the biopsy. A needle will be guided (often with the assistance of an ultrasonic image) through the tumor, avoiding the diaphragm at all costs. Once tumor tissues have been collected, they will be sent to a lab for histopathological examination. The entire process from start to finish may span as many as five visits to the vet.

An adrenal biopsy is found to be successful at collecting proper tissue over 90% of the time. Examination of the tissue will provide a specific diagnosis as high as 99% of the time. If a successful biopsy has been completed, there should be no need for a second biopsy. If the procedure has been deemed unsafe, a detailed CT scan or MRI can prove to be extremely effective at gauging the type of growth that exists in a less invasive manner. Sometimes the excision of the entire tumor will be paired with the biopsy so as to not make duplicate incisions if they can be avoided.

After the procedure has been performed, the cat should be closely monitored for two to four hours. During this period, the cat's vitals should be measured and extra care should be taken to ensure its breathing is normal. A follow-up appointment may be needed shortly after the biopsy has been completed. If the procedure had complications, more care may be required.

A full recovery is to be expected for the majority of cats who have undergone an adrenal biopsy. Diagnosis from the biopsy may lead to further treatments. If cancer is found, these treatments may be extensive, ongoing and costly. Recovery is not a guarantee, even with early detection.

As the vast majority of adrenal growths require removal, identifying the type of growth prior to surgery does not have a definite link to higher survival rates. In most cases, an excision or complete adrenalectomy will need to be performed. This will also reduce the cost by about half of the price it would be to perform the two procedures separately. Surgery costs involving general anesthesia may range from $300-$700. Non-aggressive growths may respond to Mitotane administration, which is less invasive than a biopsy or surgery, but will be needed at high doses to impact tumor size. If the growths are deemed harmless to the cat through diagnostic imaging, a biopsy may be avoided completely. Diagnostic imaging may range greatly in price, from $250-$1,000 depending on the type.

While an adrenal biopsy is a commonplace procedure, there are some risks associated with the treatment. Complications such as hemorrhage, pneumothorax, needle tract seeding and extreme pain may arise. Rate of complication occurrence is relatively low, happening in approximately 4% of instances. Severe complications requiring further treatment are even more rare, arising in about 1% of biopsies. Though it is unlikely, cats with aggressive forms of cancer may experience the cancer cells spreading to other parts of the body after a biopsy. The benefit of an adrenal biopsy is that a specific diagnosis of the type of adrenal growth is very likely to be found. 

As adrenal biopsies are only needed in cats who have developed adrenal growths, preventing these growths would end the need for a biopsy completely. This is not an easy feat, however, as the exact cause of adrenal tumors is vastly unknown. Genetics definitely come into play, so it may be best for cats that have adrenal gland issues that they not be allowed to mate. Cats who have relatives that have been diagnosed with adrenal issues are more likely to develop similar problems. Aging may also be a factor in abnormal cell growth, although there is no prevention for this natural occurrence. 

Overall contributors to cancer development in cats have been identified, and many of them affect the owners of the cat as well. Smoking indoors has been proven to cause cancer in both cats and humans. If you live in an environment with high exposure to toxins, you and your pets will also be at a heightened risk. A sedentary lifestyle may add to the risk of your cat getting cancer. By increasing play times, you both can become more active. Be sure to feed your cat a diet that is low in fat, as to not make its condition worse.