Leptospirosis in Dogs: Facts, Symptoms, Treatment & Prevention

Leptospirosis (also commonly known as lepto) is a contagious disease that all mammals may acquire at some point. Leptospirosis in dogs is caused by Leptospira bacteria. Though the disease occurs all over the world, it's more common in warm, wet climates and during rainy seasons.

In the past, hunting dogs and dogs who spent a lot of time in wild areas were at the highest risk for the disease. Now, leptospirosis is more commonly seen in urban dogs who have been exposed to the disease from mammals that live in cities, like squirrels, raccoons, skunks, moles, shrews, opossums, deer and rodents. Small breed dogs who live in urban areas and who are unvaccinated are at the highest risk for lepto.

Let's take a closer look at how this disease is spread, the clinical signs that a dog has leptospirosis and what you can do to help prevent your dog from contracting this disease.

How Is Leptospirosis in Dogs Spread?

Lepto is spread in one of two ways: by direct transmission or by indirect exposure via an environment that's contaminated with urine from an infected animal.

Leptospira bacteria get in through mucus membranes (the oral cavity, for example) or through damaged skin. Direct transmission can occur if a dog comes into contact with urine, placenta, milk or semen from an infected animal. Indirect exposure occurs when a dog comes into contact with Leptospira bacteria via a contaminated environment, either soil, food, water, bedding or vegetation. Leptospira can only survive in a warm and moist environment, and they're often found in marshy, muddy or irrigated areas where the temperature is between 45 and 96 degrees Fahrenheit (36 °C) . The bacteria can survive up to 180 days in wet soil and even longer in standing water. Freezing temperatures, dehydration or direct sunlight can kill Leptospira.

Dense animal populations, such as shelters, kennels and urban areas, are at an increased risk of lepto. The disease can be transmitted from dogs to humans, but the risk of this happening is low. Veterinarians, veterinary staff, dairy workers and livestock producers are at an increased risk for contracting lepto. It's also important to note that exposure to stagnant water also presents a risk.

Clinical Signs of Leptospirosis in Dogs

Many dogs who are infected with lepto don't show any signs at all. Whether they become ill depends on their immune systems and which species of Leptospira bacteria they're exposed to. Not all species of Leptospira cause the disease, and over 250 species have been classified worldwide. The two most commonly affected organ systems by Leptospirosis are the liver and kidneys. In Europe, certain species of Leptospira bacteria can cause severe damage to the lungs, but thankfully, these species of leptospira have not been documented in the United States.

If a dog is going to get sick, it will happen after the incubation period, which can last from four to 20 days. Acute disease happens after the incubation period and while symptoms will vary largely by what organ systems are more severely affected, general symptoms can include fever, general soreness, fatigue, and weakness. Additional clinical signs associated with the acute form of the disease include:

• Vomiting
• Loss of appetite
• Jaundice (yellowing of the eyes, skin and gums)
• Difficulty breathing
• Drinking and peeing a lot
• Diarrhea
• Elevated heart rate
• Red eyes
• Runny nose

In severe cases, leptospirosis may result in liver or kidney failure. Animals may also become infected with chronic forms of the disease, resulting in long term damage the liver and kidneys.

Diagnosing and Treating Leptospirosis in Dogs

A vet will review your dog's oral history, vaccination history, physical exam findings and laboratory tests to diagnose lepto. Your vet may order diagnostic tests, including bloodwork, urinalysis, imaging studies such as an abdominal ultrasound or radiology, and specific tests for lepto. Tests for lepto vary and are focused on either detecting antibodies against lepto in the bloodstream or detecting leptospira bacteria itself in body tissues or fluids. Antibody tests will likely need to be repeated in three to four weeks to check for rising antibody titers, which helps diagnose infection.

When dogs infected with leptospirosis are hospitalized, they are usually kept in a special isolation ward to prevent the spread of the disease to other dogs in the hospital. They're treated by veterinary staff wearing PPE (gloves, gowns and face shields) to prevent accidental contact of mucus membranes with infected urine.

Treatment consists of intravenous fluids to correct dehydration and support internal organs, and antibiotics. If a dog has severe liver or kidney failure, additional treatments to address these conditions may be needed.

Preventing Leptospirosis in Dogs

Limit your dog's access to places where Leptospira like to hide, such as marshy and muddy areas, ponds, heavily irrigated pastures and low-lying areas with stagnant surface water.

It can be difficult to avoid exposure to wildlife, like raccoons and rodents, in both urban and rural areas. If you live in an area with leptospirosis, some of which are highlighted in a study in The Veterinary Journal, getting your dog vaccinated is recommended to protect against the disease. Immunity to lepto tends to be species-specific; therefore, vaccines include the specific species of Leptospira seen in an area. If you're traveling, ask your vet if your lepto vaccine protects your dog in other geographical areas. The vaccine doesn't prevent infection; rather, it reduces the clinical signs of lepto. The vaccine requires two boosters at the beginning of the vaccine series, and then yearly boosters are recommended for most dogs thereafter. If your dog hunts, goes to dog shows or has access to water or ponds, be sure to have your dog vaccinated every six months as immunity wanes over time.