Canine leptospirosis is a bacterial infection that can have serious consequences in dogs and can also affect humans. There are multiple strains of the bacteria called Leptospira that cause leptospirosis. Prevention of leptospirosis includes vaccination, which protects against the four most common strains, and avoiding common sources of contamination.

Transmission

Leptospirosis can be found across the United States, though some regions may be more susceptible than others. The bacteria thrive in warm and wet environments, especially during late summer and into fall, and they can survive for weeks to months. Periods of heavy rainfall can make it easier to spread.

The most common way dogs get leptospirosis is through water contaminated with urine, particularly stagnant or slow-moving water like puddles, ponds or lakes. Another source is from contact with urine-contaminated soil, bedding or food.

Many different animals can spread leptospirosis through their urine, primarily rodents and small mammals like rats and raccoons, and even some livestock. Leptospira enters the body through ingestion, broken skin or mucous membranes (eyes, nose or mouth). The incubation period, or the time between exposure to the organism and the appearance of symptoms, is about one week.

Clinical signs

Leptospira attaches to cells that line blood vessels (endothelial cells) which can make it harder for blood to clot normally. The bacteria spreads throughout the body and affects organs, most notably the liver and kidneys. Signs can range from mild to severe, and sometimes become life-threatening.

These common signs may be seen in varying degrees of severity:

• Fever
• Decreased appetite
• Vomiting
• Diarrhea
• Increased thirst and urination
• Lethargy or weakness
• Stiffness and soreness

Other signs may include dehydration, yellowing of the eyes or gums (jaundice), small bleeding under the skin (petechiae), redness to the eyes (uveitis) and more. In severe cases, rapid or difficulty breathing may be noted from bleeding into the lung (pulmonary hemorrhage).

Diagnosis

Leptospirosis can be difficult to diagnose because the clinical signs may resemble many other diseases, or the vaccine history may be uncertain. Your veterinarian will recommend blood work and urine testing.

Based on these results, additional testing to confirm a diagnosis is needed such as a PCR test, which looks for DNA of the Leptospira organism, and testing for antibodies. Chest x-rays may be needed to check for a pulmonary hemorrhage.

Treatment

Leptospirosis is treated with antibiotics, most commonly doxycycline, for at least two weeks. Hospitalization with IV fluids and management of electrolytes is often necessary initially.

Additional treatments may include medications to protect the gut, prevent nausea and pain, provide nutritional support and manage blood pressure.

Outcome

Leptospirosis is responsive to antibiotics and complete recovery is possible, but some dogs that survive may be left with chronic kidney or liver disease. Some dogs may not survive if the infection has caused significant organ damage or severely affected the ability of blood to form clots.

Dogs with respiratory issues may be less likely to survive.

Zoonosis

Leptospirosis is a zoonotic disease, which means there is the possibility for it to spread from mammals to people. Gloves should be worn if handling any urine. If there is any accidental contact, hands should be thoroughly washed.

Vaccinating your dogs will decrease the risk of human exposure, as well as protecting against infection.

Prevention

Prevention is much simpler than treatment, and should include the following: 

• Vaccinate dogs annually with the leptospirosis vaccine
• Limit access to standing water
• Prevent rodent problems
• Avoid contact with wildlife

After the first vaccine, your dog will need a booster in 3-4 weeks. Your dog should then receive a booster once a year.

Updated Nov. 2024