Brain tumors in dogs

A tumor in the brain? Yes, our dogs can also get brain tumors. Brain tumors in dogs are not that rare, accounting for about 2-4.5% of the dog population. Theoretically, they can occur at any age. Since these tumors cannot be seen from the outside, they can only be detected by clinical signs and abnormalities. It is therefore all the more important to interpret clinical signs correctly and have them clarified by a veterinarian in good time.

What exactly are brain tumors?

The origin of these tumors is often the meninges, in which case we speak of so-called meningiomas. However, they can also originate from the nerve cells themselves, this is the case with astrocytomas and gliomas. In general, we distinguish between intraaxial circumferential proliferations, when the tumors originate from the brain tissue, and into extraaxial masses when they do not originate from brain tissue. Tumors of the pituitary gland (hypophysis), so-called pituitary adenomas or pituitary carcinomas are also relatively common. However, other tumors such as histiocytic sarcomas, lymphomas or plasmocytomas are also possible in this localization.

How do I know that my dog may have a brain tumor?

The clinical symptoms of a brain tumor vary and depend mainly on the location. Tumors in the cerebrum, for example, typically cause epileptic seizures. A tumor in the brainstem or cerebellum may cause gait abnormalities. A pituitary adenoma may be active, in which case patients show typical symptoms of disturbed hormone balance, for example hyperadrenocorticism or Cushings syndrome. Typical then are increased drinking in combination with increased urination, loss of muscle and poor coat quality. However, the adenoma may also be inactive. In that case, patients often present with fatigue (apathy), decreased appetite, or, in advanced stages, blindness.

A definitive diagnosis by sampling (biopsy) is not standard practice in veterinary medicine today. Therefore, the diagnosis is usually made on the basis of diagnostic imaging. In the vast majority of cases, the imaging of choice is magnetic resonance imaging (MRI), which shows the tumor and brain with clear contrast.

Brain tumors: benign or malignant?

About half of the patients are diagnosed with a benign brain tumor, for example a meningioma or an adenoma of the pituitary gland. Unfortunately, however, meningioma can also show infiltrative growth in many cases and tends to come back after surgery, i.e., recur. Metastases are generally uncommon in brain tumors. Staging for these tumors nevertheless includes a chest x-ray and, if necessary, an abdominal ultrasound or a whole-body computed tomography scan. A brain tumor is always a problematic disease because it presses on the brain tissue in a space-occupying manner and, if the patient is left untreated, usually leads to death after a few months.

How can brain tumors be treated?

Depending on the location, brain tumors can be surgically removed, but it should not be forgotten that the majority of brain tumors show infiltrative growth. This infiltration is not treated by surgery, so the tumor cannot be completely removed in many cases. In these cases, it is a matter of time before the remaining cells form a new mass. Additionally, brain surgeries are very challenging and have a high risk of complications. In contrast, radiotherapy is nowadays technically very feasible and safe in these localizations. The infiltrative part of the tumor is treated as well, patients show rapid clinical improvement in most cases, and published radiotherapy protocols rarely have significant side effects. At Equinox Healthcare, brain tumors are irradiated with 20 sessions or, alternatively, 10 sessions. In these cases, radiation therapy takes place daily for four or two weeks.

In order for a brain tumor to be irradiated, a computed tomography scan is necessary as a planning CT. In this process, a special positioning aid with a bite block, a bite impression and a vacuum mattress is produced. Based on the sectional images, an individual radiation plan is created in a special computer-based planning system. This procedure makes it possible to irradiate the tumor with a high dose while sparing the surrounding normal tissue.

For accurate and precise irradiation of brain tumors, we use individual positioning aids such as vacuum mattresses, bite blocks and bite impressions. Plastic masks are only used in exceptional cases at EQUINOX HEALTHCARE, as they rarely improve accuracy. Plus

Bite block and vacuum mattress for the positioning of a dog

In which breeds do brain tumors occur particularly frequently?

There is no clear breed or sex predisposition for a brain tumor. Intraaxial tumors are more common in short-nosed, so-called brachycephalic breeds than in other dog breeds.

What is the prognosis for the treatment of brain tumors?

The earlier a brain tumor is diagnosed, the better the chances for long tumor control. With radiation therapy, it is possible to control tumors for an average of two years with a very good quality of life. The tumors do not necessarily have to disappear. A reduction in size or stable disease often leads to the disappearance of symptoms.