While there isn't a preventative method or even a clear-cut definition as to the causes of brain tumors in dogs, we can use the causes for human brain tumors as a template. While some may be a bit extreme, Reviva Brain Reviews the general assumption is that brain tumors in humans are caused by the following: genetics, radiation exposure, serious head injuries, pesticides, cancer-causing solvents, electromagnetic fields, and possibly even nitrosamines (found in processed meats). The theories are so broad that some feel that brain tumors could be the result of any number or combination of diet, environment, genetic, chemical or immune system factors.
