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6630 NE 181st St.
Kenmore, WA 98028


With the nice weather approaching, many of us are enthusiastically planning our outdoor summer activities with the dogs. This usually includes some hiking and camping trips, making it a good time to review a potential pathogen many of us don’t think about-Leptospirosis. It is a disease caused by Leptospira (Lepto) bacteria found in livestock and wildlife including deer, raccoons, opossums, skunks, rats, and other rodents. These animals shed the bacteria via their urine into water sources where they reside.

Leptospirosis is prevalent in rural, suburban, and urban areas. The bacteria can be present in any stagnant surface water, moist soil, and recreational water sources like lakes and ponds. Natural disasters like floods may present an additional risk for exposure to Lepto.

Dogs become infected with Lepto by drinking, swimming, or walking in contaminated water. Most people are aware of the risk of getting Giardia from stagnant water but not Lepto! The bacteria enters the bloodstream through a cut in the skin, or through the mucous membranes of the eyes, ears, or nose. Once the dog becomes infected, it is highly contagious and can be transmitted to other dogs via urine. Exposure risk increases during the summer and early fall months and after periods of high rainfall.

Cats appear to have a natural resistance to infection by Leptospirosis.

The U.S. Centers for Disease Control and Prevention (CDC) estimates there are up to 200 human cases of Lepto per year contracted from dogs, other species, or their habitats. Leptospirosis is considered one of the most common zoonotic diseases worldwide. It is rarely fatal in humans but it causes serious illness.

Leptospira cause “flu-like symptoms in dogs. These include:

  • Fever
  • Dehydration
  • Loss of Appetite
  • Weakness
  • Vomiting
  • Depression
  • Diarrhea
  • Lethargy

As the disease progresses, you can either see extreme thirst and urination from kidney failure or jaundice (yellow cast in the gums & whites of the eyes) from liver failure. Severe cases may be fatal.

Diagnosis of this disease can be very challenging because the clinical signs look like many other diseases. Definitive diagnosis requires paired serum titers and urine tests that can be expensive. An accurate history, exam, and early diagnosis are crucial to the prognosis. Most cases are subclinical or chronic. Acute, severe cases require aggressive treatment with intravenous fluids, antibiotics, lengthy and expensive hospital stays.

The key to keeping your dog from getting Leptospirosis is prevention. I recommend the following measures.

  • Vaccinate Your Dog Regularly with a Quality Vaccine
    • This brings me to the hot topic of vaccination: What kind of vaccine, frequency of vaccination, and which vaccines are needed? That is a discussion you need to have with your regular veterinarian. My general philosophy is you need to tailor the vaccination protocol for the individual. Not “one size fits all”. For the purpose of this discussion, if you have dogs participating in the outdoors, I would recommend vaccinating them regularly with a high quality four way Lepto vaccine (ZOETIS/MERIAL). There are four main serotypes of Leptospira causing disease in dogs. Some of the cheaper vaccines only have one serotype included in them.
  • Avoid Stagnant Water that May Be Contaminated with Bacteria
  • Practice Good Sanitation—Wash Your Hands if Exposed to Dog Urine

In summary, due to all the rain in the PNW Leptospirosis is not an uncommon disease and is a potential public health concern. It is very a preventable disease if you follow a few simple recommendations. Have fun with your dogs this summer in the great outdoors!

For additional info regarding Leptospirosis, see the CDC information page.

Mike Bellinghausen is a D.V.M. and owner of Kenmore Veterinary Hospital. He has been practicing for about 30 years. His specialty areas of focus are orthopedic surgery, cardiology, and oncology. He and his dogs, Molly and Jazzy, enjoy agility.