Brain Tumors in Dogs

What is a brain tumor?

Brain tumors are generally classified as either primary or secondary.

Primary brain tumors originate from brain tissues or membranes covering the brain (meninges). Secondary brain tumors (metastases) have spread to the brain from a tumor in another part of the body (i.e., metastasized). 

Secondary brain tumors may also arise from nearby structures, such as the cranial nerves (high-functioning nerves that arise from the brain). Brain tumors are generally diagnosed by MRI or CT scan.

Are certain dog breeds predisposed to brain tumors?

Some dog breeds appear more likely to develop brain tumors than others. Breeds that seem especially include boxers, Bernese mountain dogs, golden retrievers, Doberman pinschers, Scottish terriers, miniature schnauzers, Boston terriers, Bouvier de Flandres, Newfoundland dogs, dalmatians, rottweilers, Welsh corgis, Labrador retrievers, Shetland sheepdogs, and Old English sheepdogs.

Collies and other dogs with long, narrow heads and noses are more likely to develop a specific type of brain tumor known as a meningioma. Meningiomas are benign tumors originating from the membranes covering the brain. French bulldogs and other short-nosed breeds are more likely to develop pituitary gland tumors and glial cell tumors, which originate from the structural cells of the nervous system. While brain tumors can occur in dogs of any age, most dogs who develop brain tumors are over the age of 5.

What causes brain tumors in dogs?

The definitive cause of canine brain tumors is unknown, although dietary, environmental, genetic, chemical, viral, traumatic, and immune system factors may be involved.

What are the signs of a brain tumor?

The most common sign of a brain tumor in a dog is seizures. Any time a new onset of seizures is observed in a dog 5 years of age or older, a brain tumor must be considered a possibility. Additional signs of a brain tumor may include:

• Abnormal behavior/mental activity
• Abnormal vision
• Circling
• A wobbly gait
• Head tilt
• Hypersensitivity to neck pain

How are brain tumors treated?

The treatments required will depend on the type of tumor diagnosed. There are three ways of treating brain tumors in dogs:

• Neurosurgery, performed by an experienced, board-certified veterinary surgeon.
• Radiation therapy, administered alone or in combination with other treatments.
• Chemotherapy medication, which may shrink the tumor and improve clinical signs.

Steroids may be used to decrease fluid buildup or to slow the growth of a brain tumor. Some dogs with brain tumors will have dramatic improvement in clinical signs for weeks or months with steroid treatment. In addition, medications to control seizures may be prescribed.

What follow-up is recommended for a dog with a brain tumor?

Follow-up care usually includes periodic examinations with or without additional imaging. If the dog develops difficulty swallowing due to increased pressure in the skull from the tumor, there is a risk of accidentally inhaling food and/or water and developing aspiration pneumonia.

The prognosis for a dog with a brain tumor is generally guarded (uncertain) to poor. Several studies suggest the prognosis for a dog with a primary brain tumor may be improved significantly by surgical removal of the tumor, radiation therapy, and/or chemotherapy.