The following case report describes the clinical and diagnostic procedure for suspected brucellosis infection in a dog. A 21 month old intact male Border Collie was presented with an enlarged right testicle and epididymis. The dog was imported to Switzerland from Germany at the age of three months, but was never abroad since then. Clinical and laboratory diagnostic investigation included bacteriology and histology. An initial serological evaluation by means of rapid slide agglutination test (RSAT) was negative. Repeated examination of the same serum by a chromatographic immunoassay (ICT) revealed a positive result. Brucella canis infection was confirmed by culture. The present case is intended to underline the importance of the suspected diagnosis of 'brucellosis' in the presence of reproductive tract problems in dogs. In addition, Brucella canis has zoonotic potential and it is imperative to comply with strict hygiene management.