Leptospirosis is a multi-organ disease of dogs, livestock and many other animals, as well as people. Various animals serve as reservoirs, including the mouse, rat, raccoon, opossum and deer. Leptospirosis is caused by different types of leptospiral bacteria. These are shed in the urine of infected animals and are transmitted by contact with water that is contaminated by the urine. Leptospiral bacteria spread to the blood and other tissues, where they reproduce and cause inflammation that damages many parts of the body, including the kidneys, liver, spleen, brain and central nervous system.

This disease is becoming more common in many parts of the United States, especially in California and areas of high-water environments. In dogs, fever, shivering and decreased appetite are the first signs that occur. Vomiting and dehydration follow. Coughing and inflammation of the eyes may also occur. Progressive deterioration in kidney function may result in decreased or no urine production. Jaundice may arise from liver damage.

Diagnostic tests for leptospirosis are often inconclusive. They include tests for liver and kidney failures. There is also a test that can detect leptospira DNA. Severely affected animals need hospitalization and intensive care. Intravenous fluids may be needed to correct dehydration. Antibiotics to kill the leptospira bacteria are started as soon as possible to reduce some of the serious and possibly fatal complications of the disease, such as liver and kidney failure. Antibiotics such as penicillin and doxycycline are always instituted. These antibiotics are given for three to four weeks. During treatment, infected animals should be isolated to prevent accidental contact with other animals. The infection may be transmitted to other animals and to humans by contact with infected urine. There is useful information about leptospirosis in pets at the Centers for Disease Control and Prevention website.

Intensive monitoring is often needed for hospitalized animals. Following recovery, laboratory tests are usually repeated to evaluate liver and kidney function. In may be necessary to disinfect areas of the animal’s environment with diluted bleach. Vaccinations are available to combat leptospirosis in dogs. Most dogs respond well to therapy with antibiotics and recover. Long-term liver or kidney disease may occur, however, even with appropriate treatment.


Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.

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