Brain tumors are a relatively common neurological problem in dogs and cats and typically affect older pets.
Certain breeds are over-represented including the Boxer, Golden Retriever, and Boston Terrier.
Clinical signs depend on the location of the tumor but may include seizures, behavior changes, compulsive circling, weakness, wobbliness, blindness, and balance problems.
Types of Brain Tumors
Brain tumors may be thought of as primary brain tumors and secondary brain tumors. Primary brain tumors arise from cells that make up the brain and its lining. Secondary brain tumors arise elsewhere and spread to the brain (metastasis).
Primary brain tumors in dogs and cats may include meningiomas, glioma, choroid plexus tumors, ependymoma, pituitary tumors, and others.
Meningiomas are the most common type of primary brain tumor in dogs and cats. They arise from the meninges (covering of the brain). They are more common in long-nosed breeds of dogs, such as the Golden retriever. They tend to be slow-growing and compress the brain from the ‘outside’ in.
Gliomas arise from the supporting cells of the brain (glial cells) and include astrocytomas and oligodendrogliomas. They are more common in short-nosed breeds of dogs, including the Boxer and Boston terrier. They tend to grow on the ‘inside’ of the brain.
Diagnosis of Brain Tumors
Clinical signs depend on the location of the tumor but may include seizures, behavior changes, compulsive circling, weakness, wobbliness, blindness, and balance problems. There are other neurological diseases that can cause identical clinical signs, and therefore further tests are warranted. A computed tomography (CT) scan may show some types of brain tumors, but magnetic resonance imaging (MRI) is considered the best imaging modality when a brain tumor is suspected. A biopsy is necessary for a definitive diagnosis.
MRI of the brain of a dog showing a glioma.
High-field MRI of the brain showing a pituitary tumor (arrow) at the base of the brain.
Large mass in the brain of a cat. Surgery was performed to remove the tumor which was a meningioma.
Treatment of Brain Tumors
Treatments of brain tumors depend on the size, location, and suspected type of tumor. Treatment options may include surgery, radiation therapy, chemotherapy, or palliative medications.