Brain Tumors in Dogs
What is a brain tumor?
Brain tumors are generally classified as either primary or secondary. Primary brain tumors in dogs originate from the tissues of the brain or the membranes covering the brain (meninges). Secondary brain tumors are also called “metastases” as they typically originate from cells that have traveled to the brain from a tumor in another part of the body (i.e., metastasized). Another example of a secondary brain tumor is one arising from the cranial nerves, which are the high-functioning nerves that arise from the brain.
Brain tumors are generally diagnosed by MRI or CT scan.
Is there a genetic or breed predisposition involved in the development of brain tumors in dogs?
The dog breeds that seem to be disposed to developing brain tumors in general include the Boxer, Golden Retriever, Doberman Pinscher, Scottish Terrier, and Old English Sheepdog.
Meningiomas are benign tumors originating from the membranes covering the brain, and they most commonly occur in breeds of dog with long, narrow heads and noses like the Collie.
Glial cell tumors originate from the structural cells of the nervous system. These, along with tumors of the pituitary gland, most commonly occur in short-nosed breeds like the Chinese Pug.
While brain tumors can occur in dogs of any age, most dogs who develop brain tumors are over the age of 5.
What are the signs of a brain tumor?
The most commonly observed clinical sign of a brain tumor in a dog is seizures. This is particularly true if the dog is 5 years of age or older when the first seizure occurs. Additional signs of a brain tumor may include:
- Abnormal behavior/mental activity
- Abnormal vision
- A wobbly gate
- Head tilt
- Hypersensitivity to neck pain
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.
How are brain tumors treated?
The treatment(s) that should be used will depend on the type of tumor that is diagnosed. There are three ways of treating brain tumors in dogs:
- Neurosurgery, which would only be performed by an experienced, board-certified veterinary surgeon.
- Radiation therapy, which might be used alone or in combination with other treatments. An experienced radiation therapist would be required.
- 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 sort of follow-up is generally recommended for a dog with a brain tumor?
In general, follow-up would include periodic examinations with or without additional imaging. If the dog develops difficulty swallowing due to increased pressure in the skull from a tumor, there is a risk for accidentally inhaling food and/or water and developing aspiration pneumonia.
The prognosis for a dog with a brain tumor is generally guarded to poor. Several studies suggest that 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.
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