Imatinib Mesylate plus Hydroxyurea Chemotherapy for Cerebellar Meningioma in a Belgian Malinois Dog

An 8-year-old intact male Belgian Malinois, weighing 37.2 kg, was referred for evaluation due to right side facial paresis, ataxia and a 2-month history of decreased cognitive ability. Physical and neurological examinations revealed mild depression, left-sided head tilt, right-sided facial paresis and ataxia. A well-demarcated, broad-based cerebellar mass and hyperostosis were found on CT imaging of the brain. Based on these CT findings, a cerebellar meningioma was strongly suspected. Hydroxyurea and prednisolone were administered; after 4 weeks, there was reduction in mass size as compared to initial CT results. However, the mass size was found to have grown 6 weeks after hydroxyurea treatment. We then prescribed a combination of imatinib mesylate and hydroxyurea. Two weeks following combination treatment, the mass size had reduced significantly. The mass continuously decreased in size until the patient died during anesthesia. Cerebellar transitional meningioma was confirmed by histopathologic examination. To the author’s knowledge, this is the first reported case of imatinib mesylate plus hydroxyurea therapy for the treatment of meningioma in veterinary medicine.