Leptospirosis is a widespread bacterial zoonosis that is estimated to cause significant illness in over one million people throughout the world every year.1 Infection is routinely identified in dogs and is a leading cause of acute kidney injury (AKI) in this species in many parts of the U.S.2,3 Leptospira are thin, motile spirochetes (Figure 1); numerous species (≈20), both pathogenic and saprophytic, have been described. Classification of these organisms is complex, as the various species contain numerous serogroups, each of which contain immunologically related serovars. Infection and clinical disease in dogs are associated with at least nine serogroups, with varying geographical prevalence. Cats appear to be inherently resistant to leptospirosis, and clinical disease is rarely reported.4 However, recent evidence suggests cats may be a significant source of environmental contamination.5
