Leptospirosis is a bacterial disease that affects dogs and other animals, plus humans too. Here are the signs, symptoms, treatments, and preventions.

By Mindy Valcarcel
August 24, 2020
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It’s pretty common for dogs to enjoy exploring the outdoors—interacting with wildlife and other canines, digging in the dirt, and diving into lakes and streams. But there’s a risk every pet parent should be aware of whenever your dog spends time outdoors or even in pet care facilities.

According to the American Veterinary Medical Association (AVMA), Leptospira bacteria, which exists in soil and water around the world, mostly in warm climates or areas with high annual rainfall, can be transmitted between animals, but also between animals and humans. Left untreated, leptospirosis in dogs can cause permanent liver and kidney damage, and even death in the most severe cases.

What Is Leptospirosis?

The infective material of leptospirosis in dogs is Leptospira bacteria. The bacteria have a literal hook at the end of its form to better take hold in victims. When a dog comes into contact with urine or water or mud contaminated by infected animals, these spiral-shaped bacteria enter through the nose, mouth, or scraped or softened skin.

Historically, infection in dogs was associated with larger breeds frequently encountering the outdoors, but according to Kathryn Primm, DVM, of Applebrook Animal Hospital in Ooltewah, TN, “lepto” as it’s commonly referred to, is starting to show up in places it wasn’t prominent in before. Furthermore, leptospirosis has spiraled into a markedly different population previously not thought to be as much at risk, such as small-breed, urban dogs. The change in the look of leptospirosis led the American College of Veterinary Internal Medicine (ACVIM) to produce an updated leptospirosis consensus statement to help guide veterinary diagnosis and treatment in 2010.

What Are Clinical Signs & Symptoms? 

According to the 2010 ACVIM Leptospirosis Consensus Statement, “Some dogs display mild or no signs of disease, whereas others develop severe illness or death, often as a result of renal injury.”

“These dogs are febrile and may be in liver or kidney failure,” Primm says. That failure of the liver or kidney can present as vomiting, diarrhea, a loss of appetite, a frequent need to urinate, and muscle tenderness. Because of its effects, lepto should be considered if your dog is showing signs of liver or kidney disease. Other symptoms include: lethargy, weight-loss, abdominal discomfort, jaundice, respiratory distress, and even blood in the urine. 

How quickly does an infection become evident? According to the AVMA, dogs can start to feel ill 4-12 days after exposure. However, “if treated early and aggressively, the chances for recovery are good.”

How Is Leptospirosis Treated?

Leptospirosis is typically treated in dogs with antibiotics. The 2010 ACVIM Consensus Statement recommends doxycycline be given orally or by injection for two weeks, though treatment duration may vary. Because of the vomiting and diarrhea, intravenous fluids may also be indicated to help keep a dog hydrated.

How Do Humans Get Leptospirosis?

Leptospirosis is one of the most widespread zoonotic diseases, meaning it can transmit from dogs to people, around the world. According to the Center for Disease Control (CDC), humans contract the bacteria the same way pets do—through bodily fluids of infected animals and contaminated soil or water. 

But the 2010 ACVIM Leptospirosis Consensus Statement has guidance at the ready for you: “Treated dogs represent a low risk to household members. In addition, urinary shedding usually does not commence until 7 to 10 days after infection, and consequently dogs in the first few days of illness also may not represent a clinically relevant source of infection. Nevertheless, until proper antimicrobial therapy is completed, owners should avoid contact with their dog's urine and wear gloves when cleaning up urine.” The ACVIM also recommends using household disinfectants if a dog has deposited urine around the house.

Does the Leptospirosis Vaccine Prevent the Disease in Dogs?

“The vaccine is tailored to the individual risk of the dog and the individual veterinary team’s recommendation,” Primm says. “In my area, we have added a lepto vaccine to our core vaccine recommendations.” 

Your veterinarian will discuss the right timing for your dog to receive a Leptospira vaccine, but two initial doses 2-to-4 weeks apart are required, per guidelines from the American Animal Hospital Association. A year after the initial dosage, an annual booster is given to keep dogs protected. The vaccine is given as early as 8-to-9 weeks of age and can be administered at any age. 

According to VCA Hospitals, possible side effects of the Leptospira vaccine include lethargy for a few days and loss of appetite. Just like in humans, there could also be soreness at the injection site. In some cases, dogs may suffer allergic reactions such a skin rash or even present anaphylactic shock-like symptoms. Your veterinarian will help you know what to look out for.

Whether you live in a high risk area or not, if you’re at all concerned about your dog’s risk for leptospirosis, consult your vet for the best course of action.