Leptospirosis

Pathogenesis

Dogs can become infected through contact with urine from infected animals or through contact with contaminated water, soil or bedding.

The organism penetrates mucosal surfaces and wet skin to enter the blood. One of two outcomes will occur depending on the status of the host’s immunity.

If the host has an adequate immune response, no infection will occur and the leptospires will be eliminated. If the host has limited or inadequate immune response, infection and disease will occur. This disease process may be subclinical or may result in clinical illness with varying degrees of severity. Organ dysfunction and failure are possible outcomes. A carrier state, characterized by shedding of leptospires in the urine, may develop.

Urine shedding begins around day four of the disease and may continue long after symptoms have subsided. While shedding leptospires, dogs pose a zoonotic threat.