Canine intracranial primary neoplasia: 173 cases (1986-2003).

This study investigates the clinical and pathologic findings associated with 173 primary brain tumors in our hospital population of dogs that presented between the years 1986 and 2002. Of the 173 primary brain tumors, 78 (45%) were meningiomas, 29 (17%) were astrocytomas, 25 (14%) were oligodendrogliomas, 12 (7%) were choroid plexus tumors, and 7 (4%) were primary central nervous system lymphomas. Smaller numbers of glioblastomas (n = 5), primitive neuroectodermal tumors (n = 5), histiocytic sarcomas (n = 5), vascular hamartomas (n = 4), and unclassified gliomas (n = 3) were identified. One dog had both a meningioma and an astrocytoma. Most tumors were located within the telencephalon, and seizures were the most common clinical presenting complaint. Of 168 tumors for which a location in the brain was recorded at postmortem examination, 79 were found to involve more than 1 brain division. Other neoplasms unrelated to the primary brain tumor were identified on postmortem examination in 39 dogs (23%). Intrathoracic and intraabdominal neoplasms were present at necropsy in 13 and 24 cases, respectively. Based on the results of this study, thoracic radiographs and abdominal ultrasonography may be indicated to look for extracranial neoplasia prior to advanced imaging of the brain or intracranial surgery.