Leptospirosis: Signs, Symptoms and Vaccinations

Leptospirosis is caused by a bacteria, of which there are many different strains. It is rare in cats, but not uncommon in dogs. Bacteria are primarily shed in the urine of infected animals, but they can also be found in other body fluids and tissues. The most common carriers of leptospirosis are raccoons and rodents (particularly rats).

Infection can occur through:

  1. Exposure to contaminated water – through ingestion, contact with mucous membranes or broken skin
  2. Exposure to urine from an infected animal – contaminated food, bedding, soil, etc
  3. Bite wounds
  4. Ingestion of tissues from infected animals

Signs and Symptoms

The severity of symptoms varies and depends on many factors, including the pet’s age, vaccination status, immune response, and the strain of bacteria. Some dogs may have mild symptoms or no symptoms at all, Leptospirosis Signs Symptoms and Vaccinationsbut severe cases can be fatal.

Signs and symptoms may include:

  • Fever
  • Joint or muscle pain
  • Decreased appetite
  • Weakness
  • Vomiting and diarrhea
  • Discharge from nose and eyes
  • Frequent urination (may be followed by lack of urination)
  • Yellowing of the gums, membranes around the eyes, and skin


As usual, if you have ANY concerns about your pet’s health, the best thing to do is schedule an appointment with your veterinarian for a full physical examination. Bloodwork during the early stages of disease may help identify damage to the liver and kidneys while it is still reversible.

Vaccination for Leptospirosis

We have had some clients express concern about reported reactions to the leptospirosis vaccine. Vaccine reactions can range from tenderness at the vaccination site to lethargy, vomiting and (in rare cases) anaphylactic reaction. The original leptospirosis vaccine, introduced in the 1980s, was much more reactive than the improved vaccines use today. However, some breeders had negative experiences with the vaccine in the past and discourage puppy buyers from vaccinating their puppies for leptospirosis.

If your pet is at risk of contracting leptospirosis due to his/her lifestyle, we feel that the potential benefits outweigh the risk of vaccine reaction. BUT the decision to vaccinate a pet is always based on open communication between the client and veterinarian. Please discuss the vaccination plan for your pet with your veterinarian, and don’t be afraid to bring up any concerns. We often “split” vaccinations into multiple visits (especially with smaller pets), and we can also give medications like antihistamines to help reduce the chance of reaction.

The leptospirosis vaccine protects against the 4 most common strains of bacteria that infect dogs. We recommend administering the leptospirosis vaccine to puppies initially at 12 and 16 weeks of age. If your older pet receives this vaccine for the first time, they will require a booster 4 weeks later.

Unlike distemper and rabies vaccines, it is important to note that the immune response to the leptospirosis vaccine has not been shown to last more than 12 months. Therefore, this vaccine must be boostered annually to be effective.

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