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A Guide to Leptospirosis

A Guide to Leptospirosis

Leptospirosis is a bacterial infection that can cause serious illness in people and animals, including your pets. As we head into fall, outbreaks can be common during this season especially after rainy periods when there is flooding and, in particular, standing water.

Leptospirosis is also a zoonotic disease – one that can be transmitted between animals and humans – so it’s important that you understand the disease and know what you can do to protect your entire family.

How Does Leptospirosis Spread?

The bacteria that cause the disease are spread through the urine (or other body fluids) of infected animals, which can then get into water or soil. There are many animals, including wild rodents and deer, that can be the source of infection or contamination of the environment.

Drinking, swimming or wading in contaminated water can put your pet at risk for the infection, as well as from bite wounds, eating infected tissue or from contact with contaminated bedding. Dogs can also get infected in kennels and in situations where they have direct contact with each other (dog parks, etc.).


Infected pets may show signs, such as:

  • Fever
  • Lethargy
  • Muscle pain
  • Increased thirst
  • Increased urination
  • Loss of appetite
  • Vomiting
  • Diarrhea
  • Upper respiratory disease (runny nose/eyes, sneezing, coughing, trouble breathing)

Cats are susceptible to the disease, too, but the signs are usually mild to nonexistent.

Treatment & Prevention

Depending on the severity of the disease and if the kidneys and/or liver are involved, treatment may include a lengthy hospital stay with IV fluid therapy, antibiotics and pain medication. Keep in mind that leptospirosis bacteria can be shed in the urine for a long period of time even with appropriate antibiotic treatment.

Although there is no vaccine for cats at this time, the most effective way to protect your dog from leptospirosis is through vaccination. Other precautions include limiting your pet’s exposure to water and areas visited by wild rodents and deer, and if you feed your pet outside, clean up any scraps of leftover food. If your pet has the infection, isolation from other family members is recommended to help control the disease, as well as practicing good hygiene for both your family and pet.

Learn More

Refer to our handout for more detailed information on leptospirosis and the strategies you can use at home to protect your pets and other family members. For any other questions you may have about your pet's health, visit our Pet Health Library, look through our Ask a Vet archive, or contact your local veterinarian with any other concerns you may have.