Leptospirosis is a disease caused by bacteria in the genus Leptospira; there are roughly 21 species, with more than 250 varieties (called serovars) that can cause disease. Because the organisms survive in surface waters (such as swamps, streams, and rivers) for extended periods, the disease is often waterborne. The disease affects virtually all mammals, including people, and has a broad range of effects, from mild, asymptomatic infections to multiple-organ failure and death.
Dogs contract leptospirosis by direct contact with infected urine or contaminated water sources, through bite wounds or otherwise damaged skin, by eating infected tissue, or exposure during birth. Once in the body, leptospires spread rapidly via the lymph system to the bloodstream and then to all tissues. If the animal mounts an immune response and survives, leptospires will be cleared from most organs and the bloodstream. However, the infection persists in sites hidden from the immune system; the most common hidden sites are the kidneys and reproductive tract. Persistence in these organs results in a carrier state; the infected animal may shed leptospires in the urine and genital secretions for months to years.
Infections may be without signs or cause various early signs. The most common pattern of leptospirosis in dogs is a sudden injury to the kidney. Signs may include lethargy, loss of appetite, vomiting, dehydration, and back pain from inflammation of the kidneys. It is also common to see changes in urination, ranging from increased volumes of urine to decreased or absent urine production. Sudden kidney failure can also lead to longterm kidney failure. Leptospirosis can also lead to sudden liver failure, with or without kidney disease. Affected dogs often exhibit jaundice (yellowing of the gums, skin, and whites of the eyes). Muscle pain, stiffness, weakness, trembling, or reluctance to move can be seen in dogs with leptospirosis. Less commonly, dogs can bleed abnormally, which appears as nosebleeds, abnormal bruising, or bloody stool or vomit. Some dogs may cough, have trouble breathing, or have inflammation within the eye. Additional signs reported in dogs with leptospirosis include vomiting, diarrhea, weight loss, fever, low body temperature, discharge from the eyes or nose, enlarged lymph nodes, and abnormal fluid accumulation in the body.
Specialized tests are available to identify the bacteria in the blood, urine, or tissue. Other tests evaluate the body's immune response to infection. Additional blood and urine tests, x-rays, and ultrasonography may also be necessary to indicate which organs are affected and what treatments are necessary.
Kidney failure and liver disease are treated with fluid treatment and other supportive measures to maintain normal fluid, electrolyte, and acid-base balance. Your veterinarian will likely recommend antibiotics to treat the cause of disease.
Commercial vaccines for dogs are available for the 4 of the most common subtypes of leptospirosis. Vaccinated dogs may still be susceptible to infections with other subtypes. Vaccination is recommended at yearly intervals. Dogs that have recently been exposed to leptospirosis may be treated with antibiotics given by mouth for 14 days to prevent infection.
Because leptospirosis can be transmitted to people, any caretakers should take appropriate precautions when handling known or suspected infected animals. Pay particular attention to avoiding exposure of skin or mucous membranes to urine or blood. Infected dogs should be allowed to urinate only in designated areas that can subsequently be cleaned and disinfected. The organisms are killed by all commonly used disinfectants. If your dog was recently diagnosed with leptospirosis, you should contact your physician with any health concerns. You should also wear gloves when cleaning up urine and should wash your hands after handling your dog, at least until antibiotic treatment is completed.
Also see professional content regarding leptospirosis.