In recent years, the number of reports describing a combination of clinical signs in cattle comprising pyrexia, hindlimb and/or udder oedema and prefemoral lymphadenopathy, consistently associated with Mycoplasma wenyonii infection, has increased. However, infection does not always appear to result in these typical clinical signs, and the factors leading to their manifestation have still to be fully elucidated. This article analyses the available evidence and suggests some options for diagnosis and management.