Leptospirosis in Dogs

Many dogs in our area love swimming at the Carmel Valley River, the beach and the lagoon, but a dangerous disease lurks in these areas – one that can sicken you as well as your dog. Leptospirosis is caused by a bacteria spread through soil, water, and the urine of infected animals. If not caught and treated early it can be deadly. Fortunately, vaccination can protect dogs from leptospirosis. Preventing your dog from drinking from puddles of standing water or from swimming in lakes, streams, or other bodies of water that may be contaminated also reduces his risk of exposure.

Leptospirosis is a potentially serious disease caused by the bacterium Leptospira. It affects dogs but can also infect a wide variety of domestic and wild animals, as well as humans.

The organism is most commonly spread through infected urine. The natural carriers of this bacterium can often live with it quite well, and shed the organism without clinical signs (opossum, rat, raccoon, armadillo, bobcat, fox, hedgehog, mouse, muskrat, shrew, squirrel, weasel, raccoon, skunk, vole, civet, deer, sea lion)… but it is the non-natural host that is infected that become gravely ill (e.g. humans, dogs).

The bacteria can survive for long periods of time in water and are frequently found in swamps, streams, lakes, and standing water. The bacteria also survive well in mud and moist soil, and localized outbreaks can occur after flooding or heavy rains.

Once a dog is infected, the leptospirosis organisms rapidly advance through the bloodstream leading to fever, joint pain, and general malaise. Because the organism settles in the kidneys and actually reproduces there, inflammation and even kidney failure may develop. Liver failure is another common consequence of infection.

Diagnosis (through multiple blood tests) and treatment (often hospitalization) can be challenging and the infection can often be fatal. It is important to watch for these early symptoms and signs and seek medical treatment immediately if concern for infection:

Weight loss


Inappetence (appetite loss)



Muscle and/or joint pain


Bloody urine

Excessive thirst


Excessive bleeding

There is no breed predilection for leptospirosis, but dogs in our rural area, hunting dogs and those with exposure to creeks, rivers, streams and the beach should all be routinely vaccinated to prevent infection.

In 2017, UC Davis School of Veterinarian published updated vaccination recommendations. Due to the increasing prevalence of leptospirosis in California it is now recommended that all dogs in California be vaccinated against this bacterial infection.