Steroid responsive meningitis-arteriitis (SRMA) is an immunemediated disorder commonly recognised in dogs in small animal practice. Two different forms of SRMA may occur. The typical, acute form of SRMA is characterised by cervical rigidity, pain, pyrexia and a polymorphonuclear pleocytosis of the cerebrospinal fluid (CSF). In a less common, chronic form of SRMA, additional neurological deficits consistent with a spinal cord or a multi-focal neurological disorder may be present, often accompanied by a mononuclear CSF pleocytosis. The prognosis for young dogs in the acute stage of SRMA is relatively good with early and aggressive anti-inflammatory or immunosuppressive therapy. In more protracted, relapsing cases of SRMA the prognosis is guarded, and therapy requires more aggressive, long term immunosuppression. The complete etiopathogenesis of SRMA is unknown; however, an aberrant immune response directed against the central nervous system (CNS) is most likely. Neutrophilic pleocytosis in SRMA seems to be facilitated by chemotactic factors in the CSF and upregulation of integrins and metalloproteinases that disrupt the blood brain barrier. Upregulation of IgA, induced by a Th2 immune response, also plays a central role in the pathogenesis of SRMA.