Causes of Canine Brain Tumors
Since there are a number of different types of primary and secondary tumors that can affect the brain, there is no responsible or accurate way to describe the causes of brain tumors in general terms. In most cases, the causes of cancer remain uncertain. Heredity is thought to play a role in many tumors of the brain and other organs or tissues. Other things that have been suggested as causing or contributing to brain tumors in dogs include dietary, environmental, viral, bacterial, parasitic, chemical, immunologic and traumatic factors. Most brain tumors in dogs are solitary masses, although this is not always the case.
While the underlying reasons for brain tumors are poorly understood, what actually causes the observable effects of those tumors has been fairly well identified. Once a tumor develops in the brain, either from primary brain tissue or as a result of metastasis from a distant location, the normal brain tissue will be physically compromised, compressed and/or displaced. As a result, brain tissue in the surrounding areas may begin to die (this is called necrosis). The pressure of the blood and cerebral spinal fluid within the brain and skull can rise to extremely dangerous levels, to the point of causing brain hemorrhage (bleeding), herniation (bulging out at abnormal places, such as at the base of the skull) and/or excessive accumulation of fluid on, in or around the brain (hydrocephalus; cerebral edema). Obviously, when these conditions occur in the brain, the consequences can be devastating, irreversible and eventually fatal. At a minimum, masses in the brain can cause changes in a dog’s behavior, attitude and mentation.
There is no reported way to prevent brain tumors in domestic dogs. Cancer of any type, in any species, remains one of the most researched of all medical disorders.
The brains of domestic dogs are a more common site of primary tumors (tumors of brain tissue) than are the spinal cord or peripheral nerves, which are also parts of the nervous system. Tumors of the middle or inner ear are much less likely to metastasize to or invade brain tissue than are tumors of the nasal cavities.