Brain Tumors in Cats

What Are Brain Tumors in Cats?

Brain tumors are made up of abnormal cells that either develop within the brain (primary tumors) or originate elsewhere in the body and spread to the brain (secondary tumors).

Brain tumors can be benign (non-cancerous) or malignant (cancerous). A brain tumor looks like a mass within a section of the brain. As the tumor grows, it may either invade a cat’s brain or press against it, leading to increased intracranial pressure, inflammation, and damage to healthy brain tissue. 

Primary brain tumors are known to account for less than 2% of tumors in cats. However, the low incidence may mislead because many go undiagnosed. Diagnosis requires advanced imaging, which is often declined by pet parents due to cost. 

The most common brain tumor in cats is a benign tumor called a meningioma. Other common brain tumors in cats include gliomas, lymphosarcoma (lymphoma), choroid plexus papillomas, and pituitary tumors.

Brain tumors can be a medical emergency due to concerning symptoms, such as seizures, sudden blindness, or difficulty walking. If your cat is displaying any of these symptoms, take them to the nearest emergency hospital as soon as possible.

Symptoms of Brain Tumors in Cats

Symptoms of brain tumors can vary based on where the tumor is located within a cat’s brain, and may include:

• Lethargy

• Weight loss

• Change in personality

• Blindness

• Misaligned eyes (strabismus)

• Restlessness

• Weakness in all four limbs (tetraparesis)

• Vocalization

• Involuntary eye movements (nystagmus)

• Muscle spasms causing the head, neck, or back to arch backward (opisthotonus)

• Walking in circles

• Lack of coordination

• Loss of balance

• Difficulty swallowing

• Difficulty breathing

• Head tilt

• Seizures

• Head tremors

• Paralysis

• Coma

Causes of Brain Tumors in Cats

It’s unknown what causes brain tumors to develop in cats. There are some theories that certain factors—such as pH abnormalities (brain tissue becomes too acidic or too alkaline), metabolic imbalances (altered metabolism), or cerebral edema (swelling of the brain)—may play a role in the development of brain tumors, but these theories have yet to be proven. 

Cats over 10 years of age are more likely to have a brain tumor than younger cats.

One study showed an increase in meningiomas in domestic short-haired cats, while another study showed a higher incidence in Siamese cats. Some researchers also found a higher incidence of meningiomas in male cats. However, further studies are needed to confirm these results.

How Veterinarians Diagnose Brain Tumors in Cats

If your veterinarian suspects a brain tumor, they may use a combination of tests to reach an accurate diagnosis, including:

• Medical history—It’s important to let your veterinarian know about any symptoms your cat has been displaying at home.

• Physical exam—In addition to a thorough physical exam, your veterinarian will perform a focused neurologic exam. Any neurologic abnormalities they detect can help them localize the problem to a specific part of the brain. However, a normal neurologic exam does not rule out a brain tumor.

• Blood work and urinalysis—These routine tests will screen for diseases affecting the entire body and determine if a cat can safely undergo anesthesia and surgery.

• Advanced imaging—To accurately diagnose a brain tumor, an MRI or CT scan of the brain is required, which involves the cat being placed under general anesthesia. An MRI is preferred because it provides more detail.

• Biopsy—A CT-guided biopsy, which involves obtaining a small sample of the brain tumor with the aid of CT imaging, may be used to determine the type of tumor. 

Treatment of Brain Tumors in Cats

Treatment of a brain tumor varies based on the type of tumor, location, and whether cancer is found in other areas of the body as well.

Treatment options may include surgery ($4,000–$7,000), chemotherapy ($2,000–$4,000), and/or radiation ($6,000–$9,000). 

The entire tumor can sometimes be surgically removed, but this is often difficult because healthy brain tissue would also need to be removed for the operation to be successful. The more brain tissue that is surgically removed, the more likely it is that neurologic problems will occur after surgery. Some meningiomas can be successfully removed with surgery, which can extend a cat’s life by up to three years, but the tumor may also regrow. 

Chemotherapy can be administered in addition to surgery or as a solo treatment option.  Lymphoma is one type of brain tumor that typically improves with chemotherapy. 

Radiation therapy is often an alternative option to surgery, and it can sometimes improve a cat’s quality of life for months.  

When cats undergo surgery, chemotherapy, or radiation, they often require hospitalization.  The amount of time a cat is hospitalized depends on the type of treatment used.

Unfortunately, most brain tumors are not curable because they are not easily accessible.

Treatment is not pursued for most cats due to cost, poor prognosis, the age of the cat, and complications that can occur. Cats who do not receive treatment often die or are humanely euthanized shortly after diagnosis.

Medications that may be prescribed for cats with brain tumors include:

• Chemotherapy drugs, such as cyclophosphamide, prednisolone, and doxorubicin, for treatment of lymphoma

• Anticonvulsant medications, such as levetiracetam and zonisamide, to manage seizures

• Prednisone, for management of cerebral edema or as a palliative treatment option

• Mannitol, hypertonic saline, or furosemide, to manage edema and reduce intracranial pressure

Recovery and Management of Brain Tumors in Cats

Recovery from a brain tumor takes time and is dependent upon the success of treatment and how the cat responds.

If a cat undergoes surgery to remove a brain tumor, the following complications can occur from the surgery or anesthesia:

• Blindness

• Progression of neurologic symptoms

• Blood loss

• Acute kidney failure

After treatment, frequent neurologic exams and blood work will be recommended to monitor the cat’s recovery.

Frequent MRI or CT scans may be recommended to assess the size of the tumor and to screen for recurrence of a tumor after surgical removal. 

Cats may stay on anticonvulsant medications (like levetiracetam and zonisamide) long-term to reduce the risk for seizure activity.

If your cat has seizures, keeping a log of any seizure activity can be helpful in monitoring recovery. Make note of the day and time a seizure occurs, how long it lasts, and how long it takes for your cat to return to normal after the seizure. Make sure to follow up with your veterinarian when any new seizures occur.

Prevention of Brain Tumors in Cats

Currently, there is no way to prevent a brain tumor from developing in a cat. Routine wellness exams are very important, because a veterinarian may find abnormalities during the neurologic exam and recommend additional diagnostic tests.