Meningiomas are a kind of brain tumor that affects dogs and arise from the meninges (the covering surrounding the brain). The incidence of brain tumors in dogs is 14.5 per 100,000. Between 40 to 60 percent of all brain tumors in dogs are meningiomas.
There does not seem to be a sex predisposition for brain tumors. Meningiomas occur in older dogs greater than 8 years old. Golden Retrievers, mixed breeds, Labrador Retrievers and boxers have the highest incidence of brain tumors although a causal effect has not been established.
Meningiomas are usually microscopically benign but due to their location adjacent to vital structure of the brain, they may be biologically devastating. Meningiomas are very slow growing tumors that compress the brain rather than invade brain tissue.
Because they are slow growing, the brain may be able to compensate (adjust to their presence). Symptoms most often associated with brain tumors are personality changes such as not playing, altered appetite, sleeping and hiding; seizures; weakness in the limbs; uncoordinated walking; or abnormal eye/facial symmetry.
Meningiomas may be quite large before they cause symptoms. Symptoms of meningiomas depend mainly on their size and their location in the brain. Symptoms are due to damage to vital brain areas and by pressure on the brain as the meningioma grows within the limited space in the skull. Symptoms may be caused by swelling and edema, which is a build-up of fluid around the tumor.
Symptoms may also be due to hydrocephalus (water on the brain), which occurs when the tumor blocks the flow of cerebrospinal fluid and causes it to build up in the ventricles. If a meningioma grows very slowly, its symptoms may appear so gradually that they are overlooked for a long time.