Leptospirosis is a bacterial disease of dogs and other mammals that primarily affects the liver or kidneys. The bacteria (Leptospira) that cause Leptospirosis, commonly called Lepto, can be found worldwide in soil and water. There are many species and serovars (strains) of Leptospira, some of which cause disease in dogs. Leptospirosis in cats is very rare and is not associated with clinical disease, but it is considered zoonotic, which means it can be spread from animals to people.
According to the Center for Disease Control, CDC, infection in people can cause flu-like symptoms and can cause liver or kidney disease. In the United States, most cases of human Leptospirosis result from recreational activities involving water. Infection resulting from contact with an infected pet is much less common, but it is possible. Those in the veterinary field, veterinarians, and staff are the group at the greatest when they handle infected dogs.
How common is Leptospirosis?
Leptospirosis is uncommon in areas where widespread vaccination of dogs is routine. Outbreaks of the disease are still seen from time to time because vaccines protect only against the four most prevalent serovars of Leptospira. Leptospirosis is more common in rural, wooded areas and areas with warm climates and high annual rainfall, but it can occur anywhere. Here in Wisconsin, we see Lepto cases in dogs, most commonly in the Spring and Fall, the wettest times of the year.
Common risk factors for Leptospirosis in dogs residing in the United States include exposure to or drinking from rivers, lakes or streams; roaming on rural properties (because of exposure to potentially infected wildlife, farm animals, or water sources); exposure to wild animal or farm animal species, even if in the backyard; and contact with rodents or other dogs. In the US, with most frequent cases are seen in the South, Midwest, East Coast, and Appalachian regions.
How are dogs infected?
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.
Dogs can become infected and develop Leptospirosis if their mucous membranes (or skin with any wound, such as a cut or scrape) come into contact with infected urine, urine-contaminated soil, water, food or bedding; through a bite from an infected animal; by eating infected tissues or carcasses; and rarely, through breeding. It can also be passed through the placenta from the mother dog to the puppies.
Signs of Leptospirosis
The symptoms of Leptospirosis in dogs vary, and with the strain, they are infected with. Some infected dogs do not show any signs of illness; some have a mild and transient illness and recover spontaneously, while others develop severe illness and death.
Certain strains (serovars) of Leptospira are more likely to be associated with disease than other strains.
There are three primary forms of the disease:
1. Hemorrhagic (bleeding) — In hemorrhagic disease, there is high fever with lethargy and loss of appetite. Multiple small hemorrhages (areas of bleeding) occur in the mouth and on the whites of the eyes. Bloody diarrhea and vomiting may occur. This form is often fatal.
2. Icteric or jaundice (liver) — The icteric or jaundice form begins like the hemorrhagic form and many of the clinical signs are the same. An additional clinical sign is a presence of a yellow color (jaundice or icterus) in the mouth and whites of the eyes. In severe cases, the skin will turn yellow.
3. Renal (kidney) — The renal form causes kidney failure. These dogs are very lethargic, anorectic (unwilling to eat), and may vomit. Their breath may have an offensive odor, and ulcers often develop on the tongue. Other signs include diarrhea, excessive drinking (polydipsia), and excessively frequent urination (polyuria). There may be red staining of the urine (caused by blood). The dog may be reluctant to move and show abdominal discomfort. Fever is variable, and temperature may actually be below normal in the more advanced stage. Dogs that survive the acute renal form may be left with chronic kidney disease.
Leptospirosis may be suspected based on the exposure history and signs shown by the dog, but many of these signs can also be seen with other diseases. In addition to a physical examination, your veterinarian may recommend some additional tests such as blood tests, urine tests, radiographs (x-rays), and an ultrasound examination.
Treatment and prevention
Leptospirosis is generally treated with antibiotics and supportive care. When treated early and aggressively, the chances for recovery are good, but there is still a risk of permanent residual kidney or liver damage.
Currently available vaccines are very effective in preventing Leptospirosis in dogs for at least 12 months.
Recommendations for at-risk dogs – and that includes all dogs in our area; that they receive an initial series of 2 vaccines given 2-4 weeks apart, followed by annual vaccination. Reducing your dog’s exposure to possible sources of the Leptospira bacteria can reduce its chances of infection but can be difficult; wildlife commonly roams through yards in our area, and dogs are attracted to where they eliminate.
Transmission to people
Although an infected pet dog presents a low risk of infection for you and your family, there is still some risk. If your dog has been diagnosed with Leptospirosis, take the following precautions to protect yourself:
- Avoid contact with your dog’s urine;
- Administer antibiotics as prescribed by your veterinarian;
- If your dog urinates in your home, quickly clean the area with a household disinfectant and wear gloves to avoid skin contact with the urine;
- Encourage your dog to urinate away from standing water or areas where people or other animals will have access;
- Wash your hands after handling your pet.
If you are ill or if you have questions about Leptospirosis in people, consult your physician. If you are pregnant or immunocompromised (due to medications, cancer treatment, HIV, or other conditions), consult your physician for advice.