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Leptospirosis In Dogs

Leptospirosis, commonly referred to as “lepto,” is a disease caused by bacteria in the genus Leptospira that can wreak havoc on many body systems in various species of animals, including humans. Below we cover some basics about this bacterial disease and why protecting your dog against it is an easy choice for many families and their canine companions!

What Is Lepto?

The Leptospira bacterial group is composed of numerous strains of a spirochete-shaped organism (think fusilli pasta!). This group of bacteria especially thrives in warm, humid / wet climates. Because of this, cases are theoretically more likely to occur in the summer months or after flooding/heavy rainfall. However, cases have been documented year-round, especially with the warmer winters we have been having. It can be hardy and survive in the environment for weeks to months. Unfortunately, these bacteria are rendered even more troublesome in that it has zoonotic potential — meaning it can be passed between animals and people.

How Is It Transmitted?

Lepto is transmitted most commonly through urine of affected animals, but can also be passed through infected tissues, bites, a mother’s milk, and via the placenta from mother to unborn baby. Urine-contaminated water or soil then serve as a mode of exposure for the next human or animal by means of mucous membranes (think mouth/lips), open cuts/wounds, etc. It can be hardy and survive in this environment for weeks to months. Rodents, livestock, wild mammals, and even other dogs can serve as “spreaders” of this bacteria. Cats in theory can become infected but this is not well documented.

Signs And Systems Affected

In dogs, the incubation period from time of exposure to start of symptoms is thought to be roughly one week. The difficult part about this disease is that a number of different signs can be seen, many of which are vague or non-specific for this disease-process, which makes pinpointing it as the cause challenging at times. This disease can be mild and cause no outward signs at all, or could culminate in a possibly fatal presentation where kidneys, liver, lungs, eyes, and/or the blood and vascular systems are affected. One of the biggest long-term concerns in dogs significantly affected by leptospirosis that survive include potentially lasting kidney and/or liver effects.


Once a diagnosis is confirmed with specific testing, treatment typically involves appropriate antibiotic therapy and supportive care. Given the wide range of organ systems that can be affected and varied severities of disease possible with this bacterial infection, treatment must be tailored to each individual case. Unfortunately, some pets still perish from this disease even with aggressive hospitalization, dialysis, and treatment.

Prevention = Vaccination

Because of its ability to cause life-threatening illness, we often recommend vaccination against this bacteria based on your dog’s lifestyle. Dogs with an active, outdoorsy lifestyle are good candidates for this vaccine. Since this bacteria can be harbored by urine-contaminated soil and water from wildlife, even dogs with access to a backyard or rodent-infested city streets are theoretically at risk. There is no vaccine available for cats, so avoidance is best. Most commercially available vaccines against leptospirosis cover for the 4 most common strains (serovars) of this bacteria. Vaccination affords good protection against this significant disease if your dog is exposed and protection generally is thought to last ~12 months once the vaccine series is complete. Some of the newer vaccines have even been shown to reduce urinary shedding of this bacteria in exposed dogs that are vaccinated, meaning exposure of other household members may be reduced as well. Just like any vaccine, 100% protection is not possible, so one must also practice avoidance (such as discouraging your pet from drinking from standing bodies of water) whenever possible.

Let us know if you feel your dog’s lifestyle puts them at risk for exposure to lepto and we can discuss whether starting the vaccination series for this bacteria is the right choice for you and your furry friend!

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