Leptospirosis is a disease is caused by spiral shaped bacteria called leptospires. It occurs worldwide and can affect humans as well as many wild and domestic animals, including dogs and cats. Dogs become infected by leptospires when abraded skin comes into contact with the urine of an infected host.  The bacteria can enter the body through skin or mucous membranes (eyes, nose, or mouth), especially if the skin is broken from a cut or scratch. Drinking contaminated water can also cause infection.  The organisms quickly spread through the bloodstream leading to fever, joint pain, and general malaise which can last up to a week. The organism settles in the kidneys and begins to reproduce, leading to further inflammation and then kidney failure. Depending on the type of leptospire involved, other organ failure (especially liver) can be expected as well.  The clinical signs of leptospirosis vary and are nonspecific.   Sometimes pets do not have any symptoms.

Leptospirosis bacteria multiply rapidly after entering the body. The time between exposure to the bacteria and development of disease is usually 5 to 14 days, but can be as short as a few days or as long as 30 days or more..   Signs of the disease can begin as soon as two days after exposure or as long as 26 days after contact with infected urine, but generally occur within one-to-two weeks.

Common clinical signs reported in dogs include:

  • fever,
  • vomiting,
  • abdominal pain,
  • lethargy,
  • diarrhea,
  • refusal to eat,
  • severe weakness,
  • depression,
  • stiffness,
  • severe muscle pain,
  • inability to have puppies.


Leptospirosis primarily affect the kidneys and liver.  Generally younger animals are more seriously affected than older animals. Make no mistake, leptospirosis is a life-threatening disease.   In extremely acute cases, a dog may suddenly go into shock and succumb.”

If your pet has become infected, it most likely came into contact with leptospires in the environment or infected animals. Your pet may have been drinking, swimming, or walking through contaminated water. Because of increased building and development into areas that were previously rural, pets may be exposed to more wildlife, such as raccoons, skunks, squirrels, opossums, or deer that are infected with leptospirosis. Dogs also may pass the disease to each other, but this happens very rarely.

In severe cases the whites of the dog's eyes turn yellow (jaundice).  This is an indication of hepatitis with destruction of liver cells.  Coagulation problems can ensure, with spontaneous bleeding from the mouth, and the presence of blood in the stools.

Once diagnosed, lepto can be treated with common antibiotics such as penicillin, tetracycline, and erythromycin. In advanced cases, therapies to deal with any liver or kidney involvement will also be necessary, but veterinarians are unlikely to suspect lepto in the early stages of the disease because the symptoms are variable and lepto caused by previously implicated strains has gone off the screen as a threat in most of the nation. Initial suspicions are often aroused by blood tests that show liver or kidney involvement, and the disease is confirmed by finding the bacteria in a urine sample or in a liver or kidney biopsy.

A dog that has recovered from disease caused by one strain of leptospirosis will be protected from disease caused by that strain in the future, but that protection does not cross species. Therefore, the dog will remain susceptible to other forms of the disease. Vaccines to protect against the disease must attack each specific strain in order to be effective. To confuse matters even more, vaccinated dogs can have mild cases of the disease that show few or no symptoms and can shed the bacteria in their urine, thus spreading the infectious agent.

Canine leptospirosis is widespread in the United States. However, the incidence varies with the environment and is less common in confined dogs.


*  some information collected from the Dog Owner's home veterinary handbook


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