Teach an old dog new tricks: Meningoencephalitis of unknown origin (MUO) in Australian shepherd dogs

Abstract

AbstractMeningoencephalitis of unknown origin is mostly considered a disease of young small dogs and terrier breeds, while older dogs presenting with clinical signs of deteriorating encephalopathy are more commonly diagnosed with intracranial neoplasia. In this case series, three Australian shepherd dogs, 7, 10 and 11 years old, were diagnosed with meningoencephalitis of unknown origin; with serial magnetic resonance imaging in two dogs and postmortem examination in one dog. Follow‐up magnetic resonance imaging examination after 4 months showed complete resolution of magnetic resonance imaging abnormalities in one dog treated with prednisolone. The other dog had a recurrence of clinical signs and multifocal de novo lesions noted in magnetic resonance imaging done at 23 months after diagnosis and tapering of prednisolone. In older dogs, a diagnosis of intracranial neoplasia should not be assumed based on clinical signs of deteriorating encephalopathy alone, and meningoencephalitis of unknown origin should be on the differential list. Older dogs diagnosed with meningoencephalitis of unknown origin can have good outcomes with immunomodulatory therapy.