Steroid responsive meningitis-arthritis in the dog is a frequently occurring disease in small animal practice. However, the etiology and pathogenesis are unknown. Immunopathologic events are suspected, since IgA seems to play a central role in pathogenesis. The influence of an infectious agent is possible. To classify the nature of such an agent, we tried to find in this study an oligoclonal T-cell proliferation using Southern blot technique. This could give a hint for an infection with a superantigen. In a first step a proliferation assay was performed, proving that staphylococcus enterotoxins A and B induce a strong lymphocyte proliferation in the dog in vitro. In one out of six dogs with steroid responsive meningitis-arthritis T-cell receptor rearrangement was detected after digestion of genomic DNA with two different restriction enzymes. Therefore a superantigen influence in this specific disease seems to be possible, but could not be proven finally using Southern blot techniques.