Leptospirosis in Dogs: Why You Might Want to Skip The Vaccine

By Chelsea Hunt-Rivera / May 7, 2018
leptospirosis in dogs

What is Leptospirosis in Dogs?

dog with leptospirosis

Leptospirosis, or in short-form Lepto, is an infectious disease of bacterial spirochetes. The disease is contracted when foreign bodies known as Leptospira interrogans penetrate the skin. The Leptospira interrogans use the bloodstream to multiply and then quickly spread the infection throughout the body.

In the genus “Leptospira” there are 20 different species and over 200 different serovars. Serovars are a group of microorganisms that are closely related and have a common set of antigens. Canine Lepto is caused by at least four of these 20 different serovars.

Canine leptospirosis often causes extreme damage to the liver and kidneys and has the potential of being fatal.

Words to Know

It’s never a settling experience when you’re at your vet’s office and vocab words are seemingly being thrown around left and right. We’ll define a few just for future reference.

Define Spirochete


The spirochete is a microscopic bacterial organism. It is a flexible and worm-like, spirally twisted bacterium. When examined under a microscope, one can see just how vigorously the spirochete moves around and how it enters the dog’s system.

What does Spirochete or Spiral Shaped Bacteria do?

The spirochete is a spiral-shaped bacterium. It uses its spiral shape to burrow into the dog’s skin. Spirochete bacterium are not only responsible for canine Leptospirosis but Lyme disease as well.

What is a Zoonotic Disease

Leptospira spirochete bacteria is classified as a zoonotic disease. When a disease is zoonotic, it means it can be passed from animal to human. Veterinary staff and pet owners who are handling a dog with Leptospirosis should be very careful and take great precautions so that their dog doesn’t transmit the disease to them.

Causes of Leptospirosis in Dogs

In most cases, the Leptospirosis disease is transmitted through direct contact with the urine of an infected animal. In some instances, Leptospirosis is transmitted through contact with soil or water that has been contaminated with infected urine.

Once the infected urine penetrates soil matter or stagnant water source, it can remain contaminated and be able to infect another animal for up to six months, especially in warmer climates.

Most commonly, wild animals such as raccoons, opossums, skunks, deer, and wolves spread the infection to dogs who are then able to inadvertently spread the disease to their owners.

The Leptospira bacterium can burrow through the soft lining of the nose, eyelids, and mouth as well as enter the body through scratches or open sores on the dog’s skin.

Leptospirosis Symptoms

In many cases, particularly mild cases, canine leptospirosis is an asymptomatic infection. When a condition is asymptomatic, it means that it doesn’t have any symptoms.

Symptoms and the severity of Lepto may vary depending on geographic locations as well as the host’s immune system.

Generally speaking, young dogs tend to get sicker and show more signs of the infection than older dogs. Even still, many do not show clinical signs at all.

When dogs with Leptospirosis do show symptoms, they usually appear within 4-12 days of exposure to the bacteria and are most commonly:

  • Fever
  • Muscle pain
  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Lethargy
  • Depression
  • Blood in the urine
  • Eye and nasal discharge
  • Conjunctivitis
  • Acute respiratory distress
  • Mild swelling of the lymph nodes

Jaundice, or a yellowing of the eyes, lining of the mouth, and mucous membranes, may also occur in some cases and may be a way for owners to differentiate Lepto from a dog with simply an upset stomach.

While many cases of Lepto can be mild and without symptoms, in other cases, symptoms can be severe and the infection can rapidly spread and cause severe, irreversible damage including sudden death.

It is crucial for pet owners not to overlook what they may consider to be a stomach ache or a virus that will pass. While we know that your dog’s health and well-being is of the utmost importance to you, many of the symptoms of Leptospirosis are nonspecific, making it difficult for pet owners to realize its severity.

An infection such as Leptospirosis may clear on its own, but may also have horrific consequences for infected dogs if the case is severe and goes untreated.

FYI – What is Parvo Virus / Parvo Symptoms

We mentioned above that many infections, including Leptospirosis, have symptoms that are classified as nonspecific. This means that while indeed the symptoms are clinical signs of Lepto, they are also clinical signs of many other conditions. Regarding the nonspecific symptoms of Lepto, a common deadly virus amongst dogs known as Parvo, also has nearly the identical nonspecific symptoms.

While a mild case of Lepto may pass on its own, Parvo will absolutely not. This is all the more reason why an accurate diagnosis from a veterinarian is absolutely imperative for the well-being of any dog showing symptoms of being unwell.

First Stages of Diagnosing Leptospirosis in Dogs

Diagnosing Leptospirosis in infected dogs can prove to be challenging as there is not a simple routine blood test that can provide a simple positive or negative diagnosis. However, routine tests can provide clues that will dictate whether your veterinarian should order for additional testing.

These “clues” are most often found in abnormalities in the following routine tests:

CBC (Complete Blood Count)

Abnormalities in the CBC examine usually show up in the form of:

  • An increase in the number of white blood cells (a common sign of infection or tissue damage)
  • A decrease in the number of platelets (a sign of infection or severe disease)
  • Sometimes, a decrease in the number of red blood cells (a common sign of bleeding)

Biochemistry Test

Abnormalities in the Biochemistry test usually come in the form of:

  • High liver and/or kidney values (a sign of liver and/or kidney damage)
  • Abnormal values for sodium, chloride, phosphorous, potassium (all clinical signs of kidney damage as well as potentially serious illnesses)


Abnormalities in the urinalysis test are most commonly:

  • Diluted urine
  • The presence of protein in the urine
  • Evidence of inflammation

These three abnormalities are tell-tale signs of kidney damage. It probably goes without saying, but substantial kidney damage can ultimately lead to kidney failure which is, more times than not, fatal.

Definite Tests of Detecting Leptospirosis Interrogans

blood tests to detect leptospirosis in dogs

Your veterinarian will first perform the routine testing on your dog. If your vet discovers any abnormalities, they will likely perform one of two tests in order to make a definite diagnosis. The two tests are the DNA-PCR test and the Microscopic Agglutination test or “MAT” test.

DNA-PCR Test for Leptospirosis

The DNA-PCR test identifies the DNA of Leptospira in whole blood or urine. A urine sample is often preferred as urine tends to shower higher levels of bacteria and make it easier for the vet to diagnose.

It is known to be cheaper than the “MAT” test and allows the veterinarian to receive the results very quickly which helps in making a speedy diagnosis and begin treatment ASAP.

While DNA-PCR test is an effective and accurate way of diagnosing Leptospirosis in dogs, it does have its own set of limitations.

Perhaps the most important thing to remember regarding the DNA-PCR test is that it has to be given before any antibiotics are administered. Antibiotics easily kill of Leptospira so even a dog who has the condition may test negative when the DNA-PCR test is administered if they have received any antibiotics beforehand. (These results are known as a false negative)

“MAT” Test for Leptospirosis

The Microscopic Agglutination test (aka “MAT” test) is used to determine the amount of antibodies against Leptospira that are present in a dog’s blood. The level of these antibodies is called a titer. If the titer is high enough or has been rising over time then the veterinarian can confirm the infection is present.

While the Microscopic Agglutination test can accurately diagnose Lepto in dogs, the results often take longer to come back and many times an additional test called a convalescent sample will be necessary in order to confirm the infection is present. As you can imagine, this only delays the diagnosis even further which then delays treatment.

Treatment for Lepto in Dogs

Luckily, antibiotic therapy is usually highly effective and dogs with Lepto tend to respond right away to the treatment.

There are two parts to the antibiotic therapy used in treating dogs with Lepto.

  • Stage 1 – The first stage rapidly clears the acute infection (the most serious part of the infection) from the body.
  • Stage 2 – The second stage clears the lingering “low-grade” infection that is typically found in “carrier” dogs.

Dogs with severe cases of Lepto may have to have additional treatment or medical intervention for any liver and/or kidney damage that the disease has caused.

Prognosis of Lepto in Dogs

While the recovery time varies from dog to dog, most will make a full recovery from mild cases of Leptospirosis.

However, small numbers of the Leptospira bacteria survive in the body, most commonly in the kidney. This means that the Leptospira, although small in numbers, continues to cause a low-grade infection and leads to the body persistently shedding bacteria in the urine. Dogs that continue to carry Leptospira in their tissues are known as “carriers.”

The prognosis for severely infected dogs may not always be as promising. Often times if Leptospirosis goes untreated and turns into a severe case this also means that severe, irreversible organ damage has simultaneously occurred. Even with appropriate treatment, sometimes the damage and deterioration are too extreme to overcome.

Preventing Leptospirosis in Dogs

So, as a dog owner, how can you prevent your precious pup from contracting Leptospirosis?

A quick google search may recommend the Leptospirosis vaccine (we do not recommend this and we’ll tell you why), but there are many other ways to prevent the infection in your dog’s day-to-day life.

Contaminated Water

contaminated dog water

Leptospirosis occurs when your pup comes into contact with contaminated water or soil. Minimizing your dog’s time access to marshy or heavily irrigated areas will help to decrease the possibility of contracting Lepto.

Additionally, pet owners should minimize their dog’s possible interactions with wildlife. This will decrease the possibility of contracting Lepto as well as a slew of other potential viruses and ailments.

A Healthy Immune System

It’s not news that a healthy immune is key in terms of preventing all sorts of viruses and infections as well as speeding up the recovery process if your dog happens to contract any illness.

A healthy immune system starts with a healthy gut. If possible, we highly recommend feeding your dog a species appropriate raw food diet. A raw food diet will ensure Fido is getting the nutrients necessary to live a happy, healthy life.

Furthermore, limiting your dog’s exposure to chemical toxins such as unnecessary vaccinations, and environmental toxins such as fertilizers will only help build a stronger, more robust immune system.

Speaking of limiting vaccines…

Leptospirosis Vaccine

leptospirosis vaccine

There is in fact a vaccine for the Leptospirosis infection. However, it’s definitely not something we advocate for.

There are two huge reasons why holistic veterinarians and specialists advise against the vaccine for Leptospirosis.

The Leptospirosis Vaccine is Ineffective

First, the vaccine is not an effective immunization. Studies show that the Lepto vaccine “appears” to work, but this information is given to veterinarians by the drug manufacturing company. Of course they are going to say it appears to work.

Also, in the US and abroad there are many cases of vaccinated dogs still contracting the disease. So what’s the point?

The vaccine is also short-acting and is unable to protect against all 20 serovars of the Leptospira bacteria. In fact, the vaccine is completely ineffective for the serovars that cause the bulk of infections in many areas of the US.

Furthermore, once your family dog is vaccinated, they then shed the Leptospira microbes. Because Leptospirosis is zoonotic, this means that you and your family is now at risk for contracting the disease!

Adverse Reactions of the Leptospirosis Vaccine

Secondly, there are an extremely high and dangerous amount of adverse reactions from the Leptospirosis vaccine. The adverse reactions are quite diverse and include:

  • Renal failure (can occur and result within 48 hours of receiving the vaccine)
  • Tumors
  • Autoimmune disease
  • Kidney failure
  • Anaphylaxis
  • Lethargy
  • Vomiting
  • Diarrhea
  • Lameness
  • Dermatitis
  • Fever
  • Cancer
  • Liver failure
  • Pancreatitis
  • Mast cell disease
  • Urinary tract infection
  • Dehydration
  • Chronic weight loss
  • Enlarged spleen
  • Death

Here’s the kicker– There is not a Leptospirosis vaccine for humans and here’s why:

  • The adverse reactions are too unfavorable
  • The protection is short lived
  • There is an increased risk of developing an autoimmune disease
  • The vaccine does not protect against leptospiuria (Lepto-spira in the urine) — so it can still be transmitted

So why are vets advising for a vaccine that has far too many negative elements even to be considered for humans?

Is Your Dog at Risk of Contracting Leptospirosis

It is important for pet owners to know whether or not their dog is at risk for contracting the infection and knowing what to do in order to prevent it from happening.

Pet owners should check with their local public health department to find out whether Leptospirosis is endemic in your area. Your veterinarian should also have information on how commonly they see cases of Leptospirosis.

Leptospirosis is most common to occur in warm, moist climates where the bacteria can grow and live for up to 180 days. Tropical and subtropical climates, particularly during rainy seasons, tend to see the biggest outbreaks of Leptospirosis.

Outdoor dogs and hunting dogs are at a much higher risk of contracting Leptospirosis.

If you feel that your dog is at a high risk of contracting Leptospirosis, be sure you are doing everything you can to limit their potential exposure and boost their immune system through diet and supplements.

Leptospirosis in Humans

leptospirosis in humans

As we mentioned, Leptospirosis is a zoonotic disease, meaning that animals can transmit the disease to humans. Similarly to Leptospirosis in dogs, there is a wide array of nonspecific symptoms of Lepto in humans making it difficult to diagnose.

Symptoms of Lepto in Humans

These symptoms include:

  • High fever
  • Headache
  • Chills
  • Muscle aches
  • Vomiting
  • Jaundice (yellow skin and eyes)
  • Red eyes
  • Abdominal pain
  • Diarrhea
  • Rash

Comparable to dogs, it is possible for a human with Lepto to not have any symptoms at all.

Who is at Risk for Contracting Lepto?

The CDC states that the following humans are at a higher risk for contracting Leptospirosis due to their exposure to potentially contaminated water and soil.

  • Farmers
  • Mine workers
  • Sewer workers
  • Slaughterhouse workers
  • Veterinarians and animal caretakers
  • Fish workers
  • Dairy farmers
  • Military personnel

Lepto in humans has also been associated with kayaking, rafting, and swimming in contaminated rivers and lakes.

Furthermore, Lepto in humans can occur if a dog with the infections inadvertently passes it their owner either during the treatment process or if the owner doesn’t yet know that their dog has the infection. For this reason (among many others) it is paramount to always keep cleanliness and hygiene in mind so that the disease doesn’t pass onto you.

Treating Lepto in Humans

Antibiotics treat Lepto in humans, most commonly doxycycline or penicillin.

However, also comparable to dogs are the severe ailments that can occur if Lepto goes without treatment.

These include:

  • Kidney damage
  • Meningitis (inflammation of the membrane around the brain and spinal cord)
  • Liver failure
  • Respiratory distress
  • Death

Even with treatment, the disease can last up to three weeks or longer. Without treatment, recovering from Lepto can take several months.

The CDC (Center for Disease Control and Prevention) states that the time between a person’s contact with a contaminated source (contaminated water or soil) and the Leptospirosis symptoms appearing can be between two days and four weeks.

With the potentially long amount of time for symptoms to appear and the fact that the symptoms are nonspecific, you can see why Lepto can be hard to diagnose.

Leptospirosis – While Treatable, Should be Prevented!

healthy dog

All in all, Lepto is not the absolute worst diagnosis that your dog could receive. However, as we mentioned, it isn’t something that a pet owner should shrug their shoulders about. Leptospirosis can absolutely be deadly and cause irreversible health conditions in both dogs and their owners alike.

Preventing Leptospirosis in dogs (as well as humans) is entirely possible. By limiting exposure and making sure your pup is eating a diet that will support their immune system, pet owners can ensure that they are taking the necessary steps to keep Fido happy and healthy.

Are Bacterial Infections Contagious?

It is possible to “catch” and spread a bacterial infection when the microscopic bacteria spreads via direct or indirect contact.

The direct ways of transmission include:

  • Person to person (i.e. kissing, coughing, sexual contact)
  • Animal to person (i.e. scratching, biting, handling animal waste, being in contact with contaminated animal waste)
  • Mother to fetus (transmission through the placenta or vaginal canal during birth)

Indirect contact occurs when the bacteria is living on an inanimate object such as a doorknob and passed to an individual touching the object and then touching their nose, mouth, eyes, etc.

Indirect spreading of bacteria can also occur through insect bites or contaminated food.

So to answer your question, YES. Bacterial infections are definitely contagious, just maybe not exactly in the way you might think.


What is Lepto in dogs?

How can my dog get Lepto?

What are the signs of Leptospirosis in dogs?

How is Lepto in dogs treated?

Should my dog get the Lepto vaccine?



The Leptospirosis Vaccine: Why It Doesn’t Work











The Leptospirosis Vaccine: Why It Doesn’t Work





About the author

Chelsea Hunt-Rivera

Chelsea Rivera is a Dedicated Pet Parent who loves to create amazing content for pet owners and is helping change pet wellness as the Head of Content for Honestpaws.com.