Toy Poodle with brain inflammation managed long-term with imatinib

Abstract

A seven-year-old Toy Poodle was presented for progressive ataxia and seizure episodes. Magnetic resonance imaging revealed inflammatory lesions in the cerebrum and brainstem. Management with imatinib mesylate, prednisolone and hydroxyurea were initiated and resulted in complete resolution of the clinical signs. In regular magnetic resonance imaging scans, the overall appearance of the lesions deteriorated but improved again after an increase in the imatinib mesylate dose. The patient had not shown any neurological signs until death and survived for 1052 days after initial presentation. On histopathological examination, the patient was diagnosed with disseminated granulomatous meningoencephalitis involving the cerebrum and brainstem. Immunohistochemical staining was performed on the five types of tyrosine kinase (PDGFR-α, PDGFR-ß, VEGFR-2, c-Kit and c-Abl proteins), which constitute therapeutic targets for conventional multitargeted tyrosine kinase inhibitors. The immunohistochemical analysis revealed that all these tyrosine kinases were expressed in the brain samples. The present report describes the first case of the use of imatinib mesylate therapy for granulomatous meningoencephalitis in the dog. Therapy with imatinib mesylate plus glucocorticoids appears promising as a new therapeutic intervention in meningoencephalitis of unknown aetiology.