There are several types of brain cancer in dogs. Interestingly enough, the type of cancer a dog may be prone to is influenced by the length of his snout. Cancerous tumours in the brain have several classic symptoms but this will depend on the location of the tumour. Your veterinarian can run several tests to look for clinical signs.
The most common types of brain cancer are pituitary cell tumours, gliomas and meningiomas. Brachycephalic (short-nosed) breeds like boxers, pugs and Boston terriers are more likely to get pituitary tumours and gliomas. Meningiomas are most common in long-nosed breeds like doberman pinschers, retrievers and greyhounds.
According to Gulf Coast Veterinary Specialists, brain cancer is also common in mixed breed dogs and slightly more common in male dogs. Typically, senior dogs aged ten or older are mostly likely to be diagnosed with brain cancer.
Forebrain Cancer Symptoms
According to the oncology centre at North Carolina State University Veterinary Teaching Hospital (NCSU), symptoms depend on where the tumour is located in the brain. Symptoms may manifest gradually or appear suddenly, and it's not uncommon for them to come and go as the disease progresses.
Tumours in the forebrain--responsible for thinking and processing sensory input-- include aberrant behaviour and personality changes, constant pacing, uncharacteristic clumsiness, blindness and changes in appetite or thirst. Seizures are a classic symptom of forebrain tumours and sudden onset of seizures in a middle-aged or older dog often indicates brain cancer.
Brainstem and Cerebellum Cancer Symptoms
Brainstem and cerebellum tumours primarily affect gross motor functioning. Most common are vestibular symptoms, where the dog begins to lose balance and coordination; very similar to the symptoms of a stroke. Other symptoms can cause difficulty in breathing and swallowing. Partial paralysis and loss of eyesight are also classic symptoms of brainstem and cerebellum tumours.
Note that the process of going blind may be very slow, and often difficult to detect until the dog's eyesight is significantly impaired. Dogs are very good at adjusting to changed circumstances and learn quickly to compensate. Any unusual behaviour or loss of functioning needs to be evaluated by your veterinarian.
X-rays will not reveal brain tumours: they are diagnosed by magnetic resonance imaging (MRI) or computed tomographic (CT) scans. Images typically show cloudy or blurred spots in the brain. Because these can be mistaken for fungal or bacterial infections, a fine needle biopsy is necessary to confirm the diagnosis. A small amount of fluid is removed from the suspect area and examined under a microscope for cancer cells.
Treatment and Prognosis
Brain cancer cannot be cured, but it can often be treated to give the dog added months or years of a comfortable, normal life. If it's possible to surgically remove the tumour without harming the brain, it may be removed. However, by the time brain cancer is diagnosed it has invariably invaded the brain, and removing the visible tumour slows, but does not halt, cancerous growth. Radiation can slow tumour growth. Chemotherapy is rarely used for brain tumours because the blood brain barrier blunts its effectiveness.
Another option is palliative therapy: keeping the dog as comfortable as possible by managing pain and other symptoms. Finally, some brain cancers quickly make some essential bodily functions, like breathing or eating, impossible and euthanasia is the kindest choice.