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Leptospirosis in Dogs

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Published on
Saturday 3 June 2017
Last updated on
Tuesday 9 May 2023
Leptospirosis in Dogs (Bacterial Infection)
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Leptospirosis in dogs is a potentially lethal bacterial infection that can be transmitted to other animals, and to humans, too. Therefore, it is essential for all dog owners to reinforce their dog’s immune system so they can eradicate the threat whenever it is encountered.

What is Leptospirosis in Dogs

Leptospirosis is a life-threatening bacterial infection commonly affecting dogs caused by the bacterium Leptospira. This bacterium is coming in various strains called serovars. Of these, mainly four can contaminate domestic dogs:

  1. Leptospira canicola — dogs
  2. Leptospira grippotyphosa — opossums, skunks, raccoons, squirrels, and small rodents
  3. Leptospira icterohaemorrhagiae — pigs and rats
  4. Leptospira pomona — pigs, cattle, deers, raccoons, and skunks

Furthermore, it is important to be aware that leptospirosis is a zoonotic infection, meaning the condition can spread from infected animals to humans. Apart from dogs and humans, this bacteria is also known to infect cats, although to a lesser degree. Wild animals including opossums, skunks, and raccoons may also get it. Livestock is also sometimes infected. The leptospira bacteria usually dwell in the kidney and start to reproduce from within.

Preventing Leptospirosis in Dogs
Leptospirosis in dogs: avoid stagnating waters, rodents, and wild animals.

Symptoms of Leptospirosis in Dogs

The symptoms of leptospirosis can take up to 12 days to manifest. If you suspect that your dog has contracted the infection, look out for symptoms like:

  • muscle pain and stiffness
  • depression and tiredness,
  • vomiting,
  • fever,
  • general weakness,
  • decreased appetite,
  • eye inflammation (uveitis)
  • and dehydration.

Other indications of the condition may be conjunctivitis, jaundice, hemolytic anemia, coughing, diarrhea, and difficulty breathing.

While all of these symptoms are worrisome, the worst symptom is kidney failure, occurring with or without liver failure. Speckled gums with a dark red color and swollen mucous membrane are some more symptoms of the disease. In the case of bitches, there could be a bloody vaginal fluid discharge which can also point to a leptospirosis infection.

Sometimes, there might not be any visible symptoms of illness at all, as the infection may also be asymptomatic. But if you do find any of the mentioned symptoms, it would be a good idea to get your dog checked by a veterinarian, at least for peace of mind.

Causes of Leptospirosis in Dogs

The infection is caused by a number of closely related bacteria of the Leptospira genus. These bacteria can be found throughout the world in water and soil, being more common in regions with warm climates and high annual rainfall.

The primary reason for a dog getting infected is by drinking contaminated water, usually from stagnant water bodies like ponds. Other ways to pick the infection up are by coming into direct contact with another infected animal, its urine, or simply by consuming meat infected by leptospira. An infected animal can theoretically be a source of the bacteria for months and years after it has been initially infected, provided it can survive that long.

Every year, most veterinarians see a surge in recorded leptospirosis infections from July through December. Also, with a booming population of small rodents, rats, skunks, and raccoons in our cities and rural areas, the risk of infection by one of the Leptospira serovars is higher than ever.

How is Leptospirosis Diagnosed for Dogs?

When you get your pet to the vet, he may check the dog’s leptospirosis vaccine status, while you may be asked questions regarding whether it has been exposed to the bacteria, and if there is a history of any ailments. A complete physical examination may also be done for other relevant clinical information.

The diagnosis of a leptospirosis infection is usually confirmed after testing urine samples. Another way is to check for an ever-increasing amount of antibodies to leptospira, which exhibits an active immune reaction in a test called the microscopic agglutination test (MAT, read study.)

How to Prevent Leptospirosis in Dogs

As a potentially lethal bacterial infection, dog owners want to know the best ways to prevent leptospirosis in dogs. So then, your dog’s immune system builds the adequate defense mechanisms that will be able to fight and eradicate a Leptospirosis strain the day it is encountered.

Leptospirosis vaccine

You can vaccinate your dog against leptospirosis. But one downside of vaccination is that there are many strains of leptospira bacteria and only a few vaccines against some of them. Nevertheless, these are still useful to keep the bacteria at bay, and most veterinarians recommend vaccination for dogs that run the risk of exposure, like those living in relatively unhygienic locations.

Vaccines are, however, contraindicated for dogs that are sick, pregnant, nursing, already infected, or have weak immunity. Make sure to consult your vet before you decide to vaccinate your pet.

Side effects of the vaccine

Ironically, the vaccine for leptospirosis can also cause some unwanted and potentially discomforting side effects. These include lethargy and loss of appetite. Some dogs may start to develop skin rashes on certain parts of their body.

Toy breeds tend to go into anaphylactic shock after the administration of these vaccines. You can gather whether they are going into a shock by symptoms like diarrhea, vomiting, frequent urination, excessive salivation, increased heart rate, and seizures. The dog may even go into a coma as a result of the vaccine.

Dogs Naturally Magazine, an online blog known for dismissing regular veterinary behaviors, went as far as saying the leptospirosis vaccine was not effective. This is a stretch I wouldn’t personally make.

Taking care of some environmental factors

If you live in an area with greater chances that your dog might get infected, such as areas with considerable wildlife or dirty stagnating water reservoirs, prevent the dog from venturing out on its own and smelling rats.

Never let your pets swim in or drink from ponds or slow-moving rivers, or any other body of stagnant water. Keep it from hunting rodents and other wild animals, which are also carriers of the bacteria. If you take your dog out to the park for a stroll, make sure to never let it out of your sight.

How to avoid getting affected yourself?

You must practice extreme precaution when handling infected dogs because as mentioned before, you can become infected directly from your dog as well. The condition can turn as life-threatening for both, your pet and yourself. Always use gloves when you are handling dogs suspected of being infected by leptospirosis. Always wash your hands thoroughly once you are done. Keep your infected dog away from children, elderly people, and pregnant and nursing women.

Additionally, it is important to note that even after a dog has apparently been cured, it may still shed the bacteria through urine. You must be on guard at least for a few days just to be on the safer side.

To be perfectly thorough, you must also check and cure any other pet present in your household. Bring all of them together in order to avoid a clean pet coming back and playing with another infected pet, only to catch it again.

Leptospirosis Treatment for Dogs


In acute cases, the dog must be hospitalized, and intravenous fluids must be started to keep dehydration in check. If the dog has internal bleeding, a blood transfusion may also be necessary. Make sure your dog insurance is good enough to cover such high vet bills.

The earlier the treatment is started, the better the chances of survival. The usual method is by administering antibiotics. If the infection is diagnosed at an early stage, the preferred course of treatment is either penicillin or doxycycline. However, these medications are useless in case the infection has reached the carrier stage, requiring stronger antibiotics like tetracyclines, and fluoroquinolones.

The period of prescription lasts for at least 4 weeks. Remember that these are strong antibiotics and their side effects may turn out to be as severe as the infection they are treating. Get to know the possible side effects beforehand by talking to the vet, and reading the medicine label properly.

Take-away Points

In summary, Leptospira is the bacterium causing the infection, and it comes in several strains. Some of which are found in dirty waters, while others favor small rodents as hosts.

The available vaccine offers good protection against some of these strains, but not all of them. Therefore, as the dog owner, you still need to keep your dog away from stagnating dirty waters and woods, especially in areas notoriously known for their high level of leptospirosis infections. The bacteria like warm and humid climates, and is at their peak in the United States from June and July onwards.

Leptospirosis in dogs is a potentially life-threatening infection transmitted by one of the dozen of strains of the bacterium Leptospira.

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