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Leptospirosis in Dogs

Puppy outdoors playing in mud after rainfall
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Severity: i Medium - High
Life stage: Puppy, Adult, Senior
  • Leptospirosis is an infectious bacterial disease that can cause serious illness for both you and your dog.
  • Dogs can contract lepto through contact with urine of rodents, or wet soil and stagnant water sources.
  • After a dog has been infected with leptospirosis, it takes about seven days for symptoms to develop.
  • If your dog is showing signs of leptospirosis, it is important to see your veterinarian right away.
  • To prevent lepto, limit your dog's exposure to high-risk areas and ensure vaccinations are completed.

When you bring your dog to the veterinary clinic for his annual wellness visit, you may be asked if your dog is vaccinated for a disease called leptospirosis.

This highly infectious bacterial disease is prevalent worldwide and can cause serious illness for both you and your dog. Fortunately, there are steps you can take to reduce your dog’s risk of acquiring this disease.

What is Leptospirosis?

Collie dog outside in field

Leptospirosis is an infectious disease caused by bacterial spirochetes, a twisted type of bacterium. Leptospires primarily attack a dog’s kidneys and liver, although some dogs may also develop respiratory symptoms or bleeding abnormalities.

Leptospirosis is a fairly common disease, particularly in late summer and early fall. In the United States, it is most common in the eastern, southeastern, and midwestern states. In other parts of the world, the prevalence and seasonality of the disease is variable. Most leptospirosis infections occur after periods of heavy rainfall or flooding.

In the past, herding dogs, hounds, and working dogs tended to be the most commonly affected. Nowadays, due to urban sprawl into wildlife areas, dogs that are small, live in urban or suburban areas, and are unvaccinated now are at equal risk for develop leptospirosis.

Leptospirosis is particularly concerning because it is a zoonotic disease, meaning that it can be transmitted from animals to humans. People usually become infected through contact with the urine of an infected animal. This can include rodents, farm animals, or even pets.

Less commonly, people may be exposed to leptospirosis during recreational activities like hiking or freshwater swimming. In most people, leptospirosis causes mild illness, but some people can develop severe or even fatal infections. Children, the elderly, and the immunocompromised are at a particularly high risk of infection.

Causes of Canine Leptospirosis

Dog walking with owner through a city

Dogs contract leptospirosis from exposure to infected urine, bite wounds, ingestion of infected animals, or exposure to contaminated soil, water, food, or bedding. Contact with livestock or wildlife can increase your dog’s risk of developing leptospirosis. Dogs living in urban areas are also at risk due to contact with infected rodents and their urine.

Leptospiral organisms can live for months in moist environments. Areas with moist soil or stagnant water can be a source of infection for your dog. The spirochetes enter your dog’s body through mucous membranes, such as the mouth or nasal cavity, or through broken skin. Once the organisms enter the bloodstream, they replicate and spread rapidly.

Direct transmission from dog to dog is rare, but your dog can become infected through contact with the urine of an infected dog.

Symptoms of Leptospirosis in Dogs

Lethargic dog laying on the ground

After a dog has been infected with leptospirosis, it takes approximately seven days for symptoms to develop. In some dogs, particularly those under 6 months of age, symptoms may be rapid and severe. In others, symptoms may come on gradually and worsen over time.

Symptoms of leptospirosis in dogs can include:

  • Fever
  • Vomiting and diarrhea
  • Stiffness and pain
  • Lethargy
  • Dehydration
  • Abdominal pain
  • Bruising or bleeding
  • Increased drinking and urination
  • Loss of appetite
  • Coughing
  • Difficulty breathing
  • Reluctance to move

If your dog is showing signs of leptospirosis, it is important to see your veterinarian right away. Not only can infections be serious for your dog, but there is a risk of transmitting the disease to you or other members of your household. Identifying and addressing the disease quickly is necessary to help reduce the risk of transmission to other animals and humans.

Diagnosing Dogs with Leptospirosis

Dog with owner at the veterinary clinic

Diagnosing a dog with leptospirosis starts with your veterinarian taking a thorough history. Your vet will likely ask you about your dog’s symptoms, lifestyle, vaccination history, and any recent travel.

Your veterinarian will also perform a full physical examination, and may recommend the following diagnostic tests:

Blood Work. A complete blood count and biochemistry panel will be used to evaluate your dog’s immune system and organ function. Leptospirosis often attacks the kidneys and liver, so blood work is an important tool to evaluate these systems.

Urinalysis. Leptospirosis often affects the urinary system in dogs, so your veterinarian may recommend evaluating a urine sample. This may show changes such as protein, blood, or cellular casts (tube-shaped, small particles made of cells) in the urine. Your veterinarian will also evaluate the specific gravity of the urine, which is an indicator of kidney function.

Antibody Tests. Antibody tests may be performed in the veterinary clinic to help your veterinarian determine whether your dog has been exposed to leptospirosis. However, antibodies are only a sign of exposure and a positive result does not necessarily confirm an active infection. Your vet may recommend confirming the result by sending additional samples to a diagnostic laboratory.

Microscopic Agglutination Test (MAT) and Polymerase Chain Reaction (PCR). These specialized tests are typically performed at a diagnostic laboratory. They are often used to confirm the diagnosis of leptospirosis. It may take several days to receive the results of these tests, so your veterinarian may recommend starting treatment while you wait for the results.

Leptospirosis Treatment for Dogs

Dog at the vet with an iv

The treatment for leptospirosis focuses on antimicrobial drugs to eliminate the bacteria and supportive care to help your dog fight the infection.

Many dogs with leptospirosis will need to be hospitalized, especially during the first few days of treatment. Fortunately, dogs that receive quick and aggressive treatment usually recover from the disease.

Medications to Treat Leptospirosis

Antibiotics. Antibiotics such as doxycycline are the mainstay of treatment for leptospirosis. Your dog may receive this medication by intravenous (IV) injection, especially if he is not eating well. As your dog starts to recover, your veterinarian may transition him to an oral pill or tablet which you can administer at home.

Fluids. Aggressive intravenous fluid therapy is essential to correct dehydration and reduce damage to the kidneys. Your dog will likely be given IV fluids during the first 24-48 hours of hospitalization for leptospirosis.

Antiemetics. Many dogs feel nauseous as a result of the leptospirosis infection. Antiemetic and antacid medications may be administered either orally or intravenously to help your dog feel better and improve his appetite.

Analgesics. Many dogs with leptospirosis infections experience abdominal pain and muscle aches. Appropriate pain control can help your dog feel better, improve appetite, and speed healing.

Cost to Treat This Condition

The cost to treat leptospirosis infections in dogs varies depending on the severity of the disease. Many dogs need to be hospitalized, and some may need intensive care for several days. While a mild case of leptospirosis may be possible to treat for as little as $500, treatment of a severe case that requires hospitalization may cost $2,000-$4,000 or more.

How to Prevent Dogs from Contracting Leptospirosis

Happy dog laying outside in a forest

Dogs typically contract leptospirosis through contact with the urine of rodents or wildlife, or by accessing wet soil and stagnant water sources. Controlling rodent populations and reducing your dog’s access to high-risk areas can help reduce your dog’s chances of becoming infected.

Lepto Vaccine for Dogs

Vaccinations for leptospirosis in dogs are available. These vaccines are typically administered as a series of two injections at 2-4 week intervals. A booster vaccine must be given annually to maintain immunity. Your veterinarian can help you determine if your dog is a good candidate for this vaccine based on your geographic location and your dog’s lifestyle.

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