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Leptospirosis - A disease that can infect both pets and their owners. 

Leptospirosis is a bacterial disease that affects both wild and domestic animals. It is also a zoonotic disease, meaning it can be spread to humans. Although rare in cats, we are seeing an increase in the number of cases of leptospirosis in dogs in Washington State.


Leptospirosis is caused by a group of closely related spirochete bacteria. Although there are many strains (also called serovars) around the world, there are a few that seem to be the most important to our domestic animals. L. Bratislava, L. Autumnalis, L. Canicola, and L. Icterohaemorrhagiae serovars were detected at close to three- folds increase in King County in 2010 as compared to 2009. While the overall numbers are still low, the general trend over the last few years is concerning.


Leptospira bacteria survive in warm, wet environments and are often found in ponds or other stagnant water sources, as well as wet soil and grass. Infection typically peaks during the summer and early fall. Many of the wildlife in this area can be natural carriers of leptospira bacteria, including raccoons, rats, mice, skunks, deer, coyotes and squirrels. Livestock can also be infected. Leptospira can be found in many body tissues and is shed in the urine. Animals swimming or drinking from ponds or other water sources that are contaminated by infected urine is thought to be a major means of contracting the disease. Animals can also contract leptospirosis through contact with broken or abraded skin, contact with contaminated food, bedding, and soil as well as by ingestion of infected tissues.


Once the bacteria get into the bloodstream they travel to many organs, including the liver, kidneys, eyes, and genital tract. As the immune system fights the infection it is cleared from most organs but can persist in the kidneys. Some animals show no clinical signs of disease but they may still be shedding leptospirosis in their urine. Other animals can become seriously ill. These are the pets that are most likely to suffer from acute kidney or liver damage. In acute cases, up to 90% of affected dogs suffered kidney failure and 10-20% had liver disease or had involvement of both the liver and the kidneys. Severe cases can be fatal. Symptoms of leptospirosis can be non- specific, especially in the beginning. Fever, depression, lack of appetite, vomiting, and muscle aches are the most commonly seen initial signs. Your veterinarian can diagnose leptospirosis with blood tests. Fortunately leptospirosis bacteria are killed with antibiotics that are readily available from your veterinarian. Many animals will also need hospitalization and supportive care during the first few days of treatment.


There are steps that you can take to protect your pets from leptosporisis. Limit access to potentially contaminated water sources. Do not feed wildlife, as this not only attracts them but also rodents that may carry leptospirosis. Dogs that hike, camp or hunt with their owners are most at risk. A vaccine is available that offers protection against 4 of the more common serovars, L. Grippotyphosa, L. Pomona, L. Canincola, and L. Icterohaemorrhagiae. There is some scientific evidence of cross protection for L. Autumnalis. The vaccine offers a shorter period of protection and will need to be repeated yearly after the initial two injection series.