Leptospirosis in Dogs

Known as a zoonotic disease, Leptospirosis in dogs is caused by a type of bacteria called Leptospira that can be spread between animals and people through urine. Both pet owners and veterinary professionals should take extra precautions around animals who have been affected by this disease so that they do not contract the illness.

The most common and simple precautions that can be taken include wearing facial masks and gloves when around an affected canine. Regular hand-washing will also be essential in avoiding the spread of the infection to the eyes, nose, or mouth, or to broken skin like a papercut or other open wound.  

If a dog has urinated on a piece of bedding, a rug, or another common space, you should take caution to dispose the soiled bedding or clean the area very well with bleach to kill the disease on contact. If you or someone you know has come into contact with an affected dog, visit your local doctor as soon as possible.

This article will provide an in-depth overview of Leptospirosis on dogs, common symptoms of the disease, treatment methods, and prevention techniques.

What is Canine Leptospirosis?

Canine Leptospirosis is a canine bacterial infection that is spread through the urine of infected animals. Dogs will acquire this bacterial disease as soon as the virus comes into contact with their blood and spreads throughout the bloodstream.

There are two common strains, including Leptospirosis Grippotyphosa and Leptospirosis Pomonabacteria. If these strains were to be examined under a microscope, they would reflect a spiral shape. This unique shape is what allows the bacteria to penetrate a canine’s skin and travel through his blood.

Once the bacteria has made its way through the bloodstream, it will target the liver, kidneys, central nervous system, eyes, and reproductive system. As soon as the bacteria has reached these areas, it will begin to reproduce and cause damage. Typically, this disease is short-term and will resolve within a matter of days or weeks.

What Causes Leptospirosis?

This zoonotic disease is very common in areas that have warmer climates and high averages of rainfall. These climates might include subtropical, tropical, and otherwise wet environments. Recently in Canada and the U.S., the fall season has been the most common time of year for dogs to pick up this disease.

The cycle begins when wild animals such as skunks, raccoons, opossums, rats, wolves, and deer urinate in an outdoor area. As the bacterium has the ability to survive in an environment for long periods of time, it can hide in marshy/muddy areas, or moist soil until it is finally carried away by another animal. This can happen directly or indirectly through urination.

Pet owners should take extra precautions when spending time in nature with their canines. Common risk factors for Leptospirosis in dogs include exposure to or drinking from rivers, lakes, or streams. If a dog roams on a rural property, is exposed to wild animals or farm animals, or comes into contact with rodents or other dogs, he is at a higher risk for contracting this disease.

This disease is caught through a dog’s mucous membranes, like on the soft lining of the nose or mouth. When any of these body parts come into contact with the bacteria, they will likely contract the disease after just a few short days.

Essentially, if any part of a dog’s skin makes contact with contaminated urine, soil, water, food, or bedding they are at risk for developing this disease.

Leptospirosis can also spread if an infected animal bites a dog or if a dog consumes a carcass with infected tissues. In some other cases, the infection can be passed down through a female dog to her puppies by way of her placenta. In severe cases, this disease can cause irreparable damage or be fatal.

In the US, cases of humans contracting Leptospirosis results from recreational activities involving water. If an infected dog urinates in a public pool and a human than swims in that pool, the human may become infected. While this isn’t very common, instances like this do occur and therefore it is best to be aware of all the possibilities for contracting this zoonotic disease.

What are the Signs of Leptospirosis in Dogs?

If a dog has been in any kind of environment like one listed above, or if the pet owner believes the dog may have been in contact with this disease, there are some important symptoms and signs to be on the lookout for.

Initially, a dog may experience a canine fever from the bacterial infection developing in his bloodstream. Typically, a dog’s antibodies in his immune system will be able to fight off the bacteria. If the dog has a low immune system, then there is a greater possibility that the infection will begin to damage internal organs.

Most commonly, the disease will stay in the kidney and reproduce itself. From there, the bacteria will begin to infect the urine that will later be excreted by the dog. Thus, causing the cycle for the disease to spread.

In some cases, Leptospirosis can become fatal if the dog has a weak liver or kidneys. It is also important to note that most cases are in younger dogs compared to older dogs, as their immune systems have yet to fully develop.

In some cases, a dog infected will Leptospirosis will show no symptoms at all. This disease varies greatly from dog-to-dog, with some only experiencing mild symptoms while others lead to death in a matter of days.

If a pet owner takes notice of any of the following symptoms, it is highly recommended they make an appointment with a veterinarian as soon as possible:

Other symptoms of Leptospirosis include shivering, extreme thirst, an increase in urine, or canine inflammation around the eyes. These signs may be easier for pet owners to notice. If a dog is vomiting blood, if there is blood in your dog’s urine, or if he begins having nosebleeds, these are all signs that the infection has spread. However, this cannot be concluded until your dog has been seen and diagnosed by a medical professional.


Since Leptospirosis is a zoonotic disease, your vet must be careful when handling your dog. Likely, the veterinarian will wear protective gloves when touching him to prevent contracting the disease themselves. Bodily fluids that you should avoid contact include urine, mucous, semen, vomit, post-abortion discharge, and any other fluids that may contain the contagious bacteria.

During this visit, the pet owner will need to disclose all known health history regarding the dog and a background of the symptoms that has been witnessed thus far. The more details that can be provided, the faster your vet will be able to come up with a diagnoses.

After obtaining all relevant details, the veterinarian will likely order a chemical blood profile, a blood count, a urine sample, and possibly an electrolyte panel. If the veterinary staff is equipped to do so, they may also look at the bacterial cultures under a microscope to see how the body’s immune system is responding.

There are a number of specific tests that the veterinarian may choose to order. These tests may include the DNA-PCR test and the Microscopic Agglutination test (MAT). The DNA-PCR test is first conducted and is used to detect where the disease is currently located within the body. This test can be taken rather quickly and is typically less expensive than the MAT. However, the only way this test works is if it is taken before the dog consumes any antibiotics. If not, the test may provide a false positive and therefore skew the results.

If this occurs, then the MAT is the suggested test to diagnose Leptospira. This test detects the presence of antibodies in a dog’s bloodstream. If he has high enough antibodies or if the test shows the antibodies increasing over time, it can be concluded that the disease is present.

At this point, antibiotics may help if it’s administered fast enough, but its effectiveness will be determined by how rapidly the infection has spread throughout the dog’s body. Once infection has set in, it will quickly move through the bloodstream and into the tissues.

Unfortunately, once a dog has been infected by Leptospira, their tissues are considered a carrier for the disease. Meaning that whenever they urinate, they will still be spredding the infection.

Treatments for Leptospirosis

The most common treatments for Leptospirosis are antibiotic therapy. Dogs can respond quickly once the antibiotics has made it to their immune system. Traditionally, there are two phases of this kind of treatment. The first is working to clear the most serious of the infection from the dog’s body and the second is to clear out any lingering bacteria from the infection.

If the infection has spread so severely that liver and kidney damage has already occurred, the treatment plan will be different. The dog may be required to stay in the pet hospital to be monitored and given intravenous fluids or other therapies during his recovery.

The best news is that when Leptospirosis is treated early and aggressively, the dog has a much higher chance for a positive recovery with limited risk of kidney and liver damage.

There are available vaccinations for this infection, although they are not on the list of “core” vaccines. It may be worth speaking to the veterinary staff about this preventative option on the next trip to the vet. Once vaccinated, this shot can protect a dog for up to 12 months. Annual boosters will lower the risk of your pet contracting this infection.

Pet owners should also take extra precautions if their dog is diagnosed with Leptospirosis. Owner’s should wash their hands frequently and schedule regular doctor appointments to keep their pet in the best condition possible.

When caring for an infected dog at home, try to keep the dog in a segregated area. If there are other pets or children in the home, they should have limited access to the dog’s area to reduce the risk of contamination. Just like in dogs, some humans become infected and never show symptoms. Therefore,if you live with a dog that has Leptospirosis, you will also need to go to the doctors to make sure you have not contracted the infection.

If a pet owner has any questions or concerns about Leptospirosis, the veterinarian is always one phone call away. They are going to be the best resource to ensure the health and well-being of your canine.


  1. “How to Identify, Treat, and Prevent Leptospirosis in Dogs.” The Spruce Pets, www.thesprucepets.com/leptospirosis-in-dogs-3384712.
  2. “Bacterial Infection (Leptospirosis) in Dogs.” PetMD, www.petmd.com/dog/conditions/infectious-parasitic/c_multi_leptospirosis.
  3. “Deadly Leptospirosis in Dogs: What You Need to Know to Protect Your Dog.” Pet Health Network, www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/deadly-leptospirosis-dogs-what-you-need-know-protect-your-dog.


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