Leptospirosis in Dogs


What is Leptospirosis?

Leptospirosis is a bacterial infection that dogs can get when the Leptospira bacteria penetrate the skin and spread through the body via the bloodstream. Leptospira bacteria are usually found in warm, humid areas and in stagnant water. Wild animals such as skunks, foxes and raccoons can also be carriers of the bacteria. The bacteria is shed and spread by the urine of infected animals. Dogs can become infected through exposure to contaminated water (by ingestion or contact through broken skin), exposure to urine from an infected animal (contaminated food or bedding, etc) or through bite wounds. It is important to know that the Leptospira bacteria is zoonotic, meaning that it can be transmitted to humans and other animals.


What are the symptoms of Leptospirosis in dogs?

The bacteria spreads throughout the entire body, reproducing in the liver, kidneys, central nervous system, eyes, and reproductive system. The extent to which this bacteria affects the organs will depend on your dog’s immune system. If a dog contracts Leptospirosis the initial symptoms noticed are usually a sudden fever and an over all not feeling well. If your dog’s immune system is able to react quickly and effectively, these symptoms will resolve. Dog’s with a persisting infection will continue to be sick, showing signs such as:

  • Sore muscles, reluctance to move, weakness

  • Depression

  • Lack of appetite

  • Increased thirst and urination, may be indicative of chronic renal (kidney) failure, progressing to inability to urinate

  • Rapid dehydration

  • Vomiting, possibly with blood

  • Diarrhea – with or without blood in stool

  • Bloody vaginal discharge

  • Petechiae on the gums

  • Yellow skin and/or whites of eyes – anemic symptoms

  • Mild swelling of the lymph nodes


Even if your dog’s immune system clears the bacteria from most of the body, the bacteria can remain in the kidneys, infecting the urine. Kidney disease leading to kidney failure can also occur if the bacteria is not cleared from the kidneys properly.

How is Leptospirosis diagnosed?

Blood tests including a complete blood cell count, chemistry screen and urinalysis will be recommended. These tests will provide important information in regards to organ function and overall health. Dogs with Leptospirosis will show some abnormalities such as increased white blood cells, decreased platelets, elevated kidney and/or liver enzymes, dilute urine and other evidence of kidney damage.

If a specific diagnosis of Leptospirosis is needed, there are two tests available. The PCR test can be done on blood or urine (urine is the preferred specimen). This test is readily available and the turn around time is quick. This test needs to be done in the early stages of the disease or else the bacteria may not be detected, leading to a false negative. The second test is the Microscopic Agglutination Test. This test checks for the presence of antibodies against Leptospira in the blood. If the levels are high, the infection is confirmed.

How is Leptospirosis prevented and treated in dogs?

Dogs with a less severe infection are able to be treated as out patients with a long course of antibiotics. Antibiotic therapy is usually a 4-6 week treatment.

Dogs with a severe and quick onset of infection should be hospitalized for treatment, which can include:

  • IV fluid therapy: to replace the fluid losses from any dehydration

  • Antibiotic therapy:  to treat the bacterial infection

  • Anti-emetics: to control nausea and vomiting

  • Gastric tube: may be needed if your dog is unable to keep food down of an extended period of time

  • Blood transfusion: if your dog has a very severe infection and has been severely hemorrhaging

Dogs that have recovered but are still carrying Leptospira bacteria in their kidneys are considered carrier animals, and will continue to shed the bacteria in their urine with out showing active signs of infection.

A vaccination for the prevention of Leptospirosis is available, but is not routinely used in areas where risk is low. If you are wanting your dog vaccinated for Leptospirosis the vaccine may be hard to come by if you are not in a high risk area. Your veterinarian can advise you on the availability and usefulness of this vaccine. In Canada, the majority of the reported cases of Leptospirosis have been in Ontario.


Leptospirosis is a zoonotic disease, which means it is transmissible to other animals as well as humans. If your dog is being treated for Leptospirosis, special care is needed during treatment. Your pet should be kept separated from other pets and kids in the house. Any areas where your dog has urinated, defecated or vomited needs to be cleaned and disinfected thoroughly. Gloves should be worn when handling your pet and cleaning up after them.

Dogs, Medical InformationKari