07/17/2026
Leptospirosis is an infectious disease caused by a type of bacteria called Leptospira. The disease causes severe damage to the kidney, liver, and other organs, and may be fatal in severe cases. Bacteria are passed in the urine of infected animals and can survive in the environment for long periods in warm, stagnant water or moist soil. Dogs can get the infection from other animals, including skunks, raccoons, opossums, rats, wolves, and other dogs.
Cats can become infected through eating rodents, and may develop disease (Leptospirosis), but it is considered rare.
Leptospirosis was once more common in rural, wooded areas, but it is now commonly found in urban settings.
Leptospira bacteria are carried mainly by rats and other rodents but can be carried by almost any mammal, including people. Infected or recovered carrier dogs may act as a source of the infection. Leptospira bacteria is shed in the urine of infected animals that then contaminates soil or water. In wet conditions, the bacteria reproduce, resulting in higher numbers of infective organisms. Infection most commonly occurs when contaminated water or soil contacts an animal’s mucus membranes (i.e., gums) or damaged or diseased skin.
For instance, if a dog were to walk in contaminated mud, they may become infected through their skin if they have any skin lesions on or around their feet. Infection can also occur animal-to-animal through bite wounds, by ingestion of an infected animal (predation), sexual transmission, and transmission in utero from mother to babies. The incubation period (from infection to onset of clinical signs) is usually four to twelve days.
The most common clinical signs associated with leptospirosis are those caused by acute (sudden) kidney injury and liver dysfunction, although the bacteria can also affect other organs and functions, such as the lungs, and may cause uncontrolled bleeding, which can lead to many different clinical signs. Common signs of leptospirosis include reduced or no appetite, lethargy, and high fever.
Signs of acute kidney injury include:
vomiting, diarrhea
increased drinking, increased urination
abdominal pain
absence of urination
Signs of liver dysfunction include:
vomiting, diarrhea
icterus or jaundice (yellowing of the gums and the whites of the eyes or skin)
Signs of other affected systems:
abnormal thickening/hardening of the skin (calcinosis cutis)
abortion
bloody urine, f***s, vomit, or sneezing
coughing blood
edema causing swelling of the limbs
elevated/increased/rapid breathing
fluid around the lungs (pleural effusion) or in the abdomen (ascites)
pain, stiffness, or reluctance to move
redness and/or discomfort (squinting) in the eyes
small hemorrhages or bruises in the mouth, on the skin, or in the whites of the eyes
The leptospirosis vaccine is recommended as a routine vaccination for dogs. Annual re-vaccination is recommended to maintain the best immunity.
