Overview

Leptospirosis is an infectious bacterial disease caused by pathogenic serovars of Leptospira bacteria. More than 200 leptospiral serovars have been identified.^1,2 Only a small number of these serovars have proven to be significant for dogs. Four serovars commonly implicated in canine leptospirosis include L. canicola, L. grippotyphosa, L. icterohaemorrhagiae, and L. pomona.^1,2

Leptospira serovars are maintained in nature by numerous reservoir or maintenance hosts (ie, subclinically infected domestic and wild animals that persistently excrete leptospires in their urine and contaminate the environment).^1,2 In addition, some animals that serve as incidental hosts develop severe disease and shed bacteria for shorter periods.¹

Excreted leptospires can survive for months in water or warm, wet soil.¹ Disease transmission occurs when leptospires persisting in the environment enter the body of a new host animal (or human) via oral, nasal, or ocular mucosa or through skin that has been abraded or softened by prolonged exposure to water.^1,2

References:

1. Greene CE, Sykes JE, Brown CA, Hartmann K. Leptospirosis. In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 3^rd ed. St. Louis, MO: Saunders/Elsevier; 2006:402−417.
   
   
2. Sherding RG. Systemic bacterial infectious diseases. In: Birchard SJ, Sherding RG, eds. Saunders Manual of Small Animal Practice. 3^rd ed. St. Louis, MO: Saunders; 2006:191−203.