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Leptospirosis in dogs
Last reviewed: 04.07.2025
Leptospirosis in dogs is caused by a bacterium called a spirochete, a thin, spiral-shaped organism. There are at least four types (or serovars) of leptospirosis bacteria that can infect dogs: canicola, icterohemorrhagiae, grippotyphosa, and pomona.
Leptospira is found in both wild and domesticated animals. The bacteria are spread through urine, often via water sources, and remain active in the soil for up to six months. Rats, pigs, raccoons, cattle, skunks, and opossums are considered the primary reservoir. As settlements move toward the outskirts, domestic animals are exposed to more wild life. This may be the reason for the increase in cases of leptospirosis.
Spirochetes enter a dog's body through a break in the skin or when the dog drinks contaminated water. Dogs that spend a lot of time in water are at increased risk of contracting leptospirosis, as are dogs that drink from puddles, spend a lot of time in yards with a lot of surface runoff, or are left wet for long periods of time after rain.
Most cases are mild and may not have any clinical signs. Symptoms appear 4-12 days after infection. Fever is present in the early stages. Other signs of the disease include loss of appetite for several days, vomiting, drowsiness, depression, muscle pain, and sometimes diarrhea or blood in the urine. Leptospirosis mainly affects the kidneys and/or liver.
In severe cases, the whites of the dog's eyes (sclera) turn yellow (jaundice). This indicates hepatitis, with destruction of liver cells. Blood clotting problems may occur, including sudden bleeding from the mouth and blood in the stool. If the dog is not treated, despite recovery, it can become a carrier and shed the bacteria in its urine for up to a year.
Serovars canicola and gripotyphosa most often cause kidney damage, and serovars pomona and icterohemorrhagiae most often cause liver damage. In young dogs, all serovars most often affect the liver.
The diagnosis can be suspected based on the dog's clinical symptoms. In addition, the results of kidney and liver function tests will be abnormal. Spirochetes can be detected in urine and blood using the immunofluorescence method (fluorescent staining of antibodies). Blood tests can be performed to confirm the analysis.
Treatment: Seriously ill dogs should be hospitalized to prevent further spread of the disease and to provide more intensive care. Antibiotic combinations such as penicillin and streptomycin are effective against leptospirosis, although doxycycline is now more commonly used. Enrofloxacin and ciprofloxacin are also sometimes used. Supportive care involves controlling vomiting and diarrhea, correcting dehydration with intravenous fluids, and providing nutritional support.
Prevention: There is no vaccine against leptospirosis.
Public health concerns: People can become infected with leptospirosis in the same way that dogs can, through water. It can also be spread through contact with infected urine, so if you have a dog in your home with leptospirosis, you should take appropriate precautions. Even an asymptomatic infected dog can spread the infection.
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