Animals can become infected with leptospirosis through direct and indirect transmission.
“Animals become infected with leptospirosis through direct contact with infected urine, ingestion of infected tissues or exposure from animal bites. Indirect transmission occurs through contact with contaminated water, soil, bedding or food. Most cases of leptospirosis occur in late summer and early fall, especially after heavy rains or flooding. Exposure to stagnant water contaminated by wildlife urine appears to be a major source of infection for dogs.”
-Johnny D. Hoskins, DVM, PhD, DACVIM