Leptospirosis is an infection of bacterial spirochetes, which dogs acquire when subspecies of the Leptospira interrogans penetrate the skin and spread through the body by way of the bloodstream. Two of of the most commonly seen members of this subspecies are the L. grippotyphosa and L. Pomonabacteria. Spirochetes are spiral, or corkscrew-shaped bacteria which infiltrate the system by burrowing into the skin.
Leptospires spread throughout the entire body, reproducing in the liver, kidneys, central nervous system, eyes, and reproductive system. Soon after initial infection, fever and bacterial infection of the blood develop, but these symptoms soon resolve with the reactive increase of antibodies, which clear the spirochetes from most of the system. The extent to which this bacteria affects the organs will depend on your dog’s immune system and its ability to eradicate the infection fully. Even then, Leptospira spirochetes can remain in the kidneys, reproducing there and infecting the urine. Infection of the liver or kidneys can be fatal for animals if the infection progresses, causing severe damage to these organs. Younger animals with less developed immune systems are at the highest risk for severe complications.
The Leptospira spirochete bacteria is zoonotic, meaning that it can be transmitted to humans and other animals. Children are most at risk of acquiring the bacteria from an infected pet.