Brain Tumors in Dogs: Symptoms, Diagnoses and Treatment

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    What Are Brain Tumors?

    A brain tumor in dogs is simply a mass on the brain. The two types of brain tumors are primary and secondary:

    Primary Brain Tumors

    Primary brain tumors are tumors that arise from the brain’s tissues or the membranes that surround it (meninges). 

    Secondary Brain Tumors

    Secondary brain tumors, often known as “metastases,” are tumors that have migrated from another section of the body to the brain (i.e., metastasized). Secondary brain cancers can also develop from surrounding tissues, such as the cranial nerves.

    What Causes Brain Tumors in Dogs?

    It’s not really fully known or understood exactly what causes brain tumors but there are some environmental and genetic factors that may play a part.

    Environmental Factors

    Examples include:

    • Viral
    • Dietary
    • Chemical
    • Immune system
    • Traumatic

    Genetic Factors

    Certain breeds are more likely to develop cancer including:

    • French Bulldogs
    • Boxers
    • Doberman Pinschers
    • English Bulldogs
    • Boston Terriers

    What are the Risk Factors for Brain Tumors?

    The breed of a dog can play a role in the possibility of being predisposed to brain tumors. Breeds including the Boxer, Golden Retriever, Doberman Pinscher, Scottish Terrier, and Old English Sheepdog tend to be more prone to brain tumors than others.


    Breeds of dogs with long, narrow heads such as border collies are more likely to develop meningioma tumors. Meningiomas are cancerous tumors that arise from the membranes that surround the brain. Pituitary gland cancers and glial cell tumors, which arise from the structural cells of the neurological system, are more common in pugs and other short-nosed breeds. While brain tumors can affect dogs of any age, the majority of dogs that get them are over the age of five.

    What are Symptoms of Brain Tumors in Dogs?

    Brain tumors in dogs and cats can manifest themselves in a number of ways, depending on which area of the brain is afflicted, and these locations can determine the symptoms. Common symptoms of brain tumors include:

    • Seizures
    • Unusual behavior
    • Loss of vision
    • Increased or decreased water and food intake
    • Head and neck pain
    • Nausea 
    • Unsteady 
    • Weight loss/gain
    • Persistent cough

    How are Brain Tumors Diagnosed?

    x ray of a dog's brain tumor
    Photo Credit: Fitzpatrick Referrals

    The only way to definitively diagnose brain tumors in dogs is to take a tissue sample. Radiographs (x-rays) or ultrasonography of other anatomical locations can be utilized to find or rule out initial cancers that have progressed to the brain. The suggested diagnostics for verifying the diagnosis of primary or secondary brain cancers are magnetic resonance imaging (MRI) or computed tomography (CT) of the brain. Blood, urine or spinal fluid samples may also be taken to assess organ function as well as to possibly determine the cause of the seizures.

    What is the Treatment for Brain Tumors?

    Treatment for brain tumors in dogs is very similar to that of treatment in humans. Surgery, radiation therapy, and chemotherapy are the three main treatment choices for dogs who have been diagnosed with brain tumors. The main goals of these treatments are to eliminate or shrink the tumor, as well as to minimize side effects such as fluid build-up in the brain These treatments can be performed alone or in combination with each other.


    Surgery is used to try and completely remove the tumor and is the ideal treatment if the tumor CAN be fully removed. Surgery also allows the veterinarian to take a sample of the mass and determine its type, making it possible to provide a more precise forecast of the patient’s prognosis. Not all brain tumors in dogs and cats can be surgically removed; the feasibility relies on their location in the brain. Tumors on the surface of the brain are more likely to respond to surgery. The surgeon would have to cut through a big section of healthy brain tissue to reach a tumor deep within the brain, which might have disastrous consequences for the patient’s recovery.

    Photo Credit: PennVet

    Radiation Therapy

    Photo Credit: Colorado State University

    Radiation treatment can alleviate symptoms dramatically and quickly. In most cases, the advantages of this medication greatly exceed the hazards. Although adverse effects from radiation therapy are uncommon in animals, they can include nausea, mouth ulcers, ear infections, and, in rare cases, blindness. Unfortunately, radiation seldom entirely eliminates the tumor, and the typical duration between remission and recurrence is 8 to 14 months.


    Chemotherapy medication is a common treatment for cancer but because the brain is a relatively protected place and most medications cannot reach it, there are limited chemotherapeutic alternatives for brain tumors in dogs. This treatment, on the other hand, could be able to assist a patient with a brain tumor minimize some of the symptoms they’re experiencing.

    Photo Credit: CAVE Veterinary Specialists

    What is the Prognosis for Brain Tumors?

    The prognosis of brain tumors in dogs can be dependent on the treatment route or if the dog owner decides not to treat. Unfortunately, due to the outlandish cost, it’s not always possible to treat dogs for cancer and it’s the most common route. Some dogs are treated without the tumor type being determined. But as CT-guided biopsies become more common, there is more research being done on the prognosis and life expectancy of dogs with cancer including with different treatments and if they are not treated at all.

    Brain tumors are uniquely difficult due to their location and the brain tissue that they affect. They first emerge in the brain cavity’s limited space. The cranial cavity, which encloses and protects the brain, is formed by the bones of the skull. While it is vital to conserve a delicate structure like the brain in this way, it also means that there is no room for anything else within the cavity, and when a tumor grows, it compresses the brain around it. Second, because brain tissue can not regenerate, removing normal brain tissue around a tumor may have adverse outcomes.

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