Leptospirosis Vaccine: What Is It, and Does Your Dog Need It?

Leptospirosis is a disease that’s caused by infection with Leptospira bacteria, also referred to as leptospires. It’s part of a group of bacteria called spirochetes, which also includes the bacteria that are responsible for illnesses like syphilis and Lyme disease. (Leptospira itself does not cause these diseases, however.)

Though it is most often diagnosed in dogs who are over 2 years old, it can impact puppies more significantly if they should catch it. It’s also a disease that can affect humans, which means your dog can pass it on to you if they become infected.

“The bacteria are typically spread through the urine of infected animals, as well as contaminated water sources, soil, or food,” notes Andrea Johnston, DVM, board-certified small-animal veterinary internist based in Minnetonka, Minnesota, and medical board member at The Vets.

Symptoms include:

• Lethargy
• Vomiting
• Decreased appetite
• Diarrhea
• Fever
• Bruising
• Edema (swelling of the limbs or abdomen)
• Bleeding from the gums
• Blood in the urine, stool or nose
• Jaundice

If your dog contracts leptospirosis, it’s considered a medical emergency.

Sarah Wooten, DVM, veterinarian in Silverthorne, Colorado, says that infected dogs and people can develop fatal liver failure or kidney (renal) failure and are very infectious to other dogs and people.

Leptospirosis flourishes during warm and wet times of the year and is particularly common in warm climates with high annual rainfall. Areas that are considered a hotspot for leptospirosis include the midwestern, southwestern, and eastern regions of the United States. But it can occur anywhere—especially after heavy rainfall and flooding—according to the American Veterinary Medical Association.

In the past, leptospirosis in dogs was primarily seen in canines who lived in rural areas, wet areas, farms, or areas with wildlife/rodent traffic. However, in recent years “the main risk factors for leptospirosis have changed, and now include unvaccinated dogs, small-breed dogs, and even dogs that live in urban areas,” Dr. Wooten notes.

Fortunately, leptospirosis tends to have a short shelf life and doesn’t live in the environment very long. If you are walking your dog by streams, rivers, or puddles, don’t let your dog drink the flowing or standing water. This minimizes the chances of contracting lepto (as well as the microscopic parasite giardia) from the river.

The 4-serovar leptospirosis vaccine is an effective preventive measure that helps keep dogs from contracting this fatal infection.

“The vaccine is usually administered as a series of initial shots, followed by annual booster shots to maintain immunity,” Dr. Johnston says.

This is a “killed vaccine,” meaning it contains inactivated bits of lepto bacteria. If the concept makes you feel nervous, it may help to know that the leptospirosis vaccine is no more reactive than a common rabies vaccine, Dr. Wooten notes.

“The bacterium [in the vaccine] does not cause the disease and has a less strong and shorter immune response than [diluted] vaccines,” adds Becca Boronat, DVM, board-certified veterinarian with Best Friends Animal Society in Charleston, South Carolina. “This is why it’s so important to follow the administration schedule of initial two doses of vaccine two to four weeks apart and then yearly boosters.”

If you have a dog who is sensitive to vaccines, or a very small dog, ask your veterinarian about breaking up vaccines into multiple visits, so your dog has a chance to recover in between vaccines.

Booster shots are necessary to ensure ongoing protection, says Dr. Johnston, as immunity can decline over time. Generally, an annual booster is recommended. However, the frequency of booster shots may depend on the specific vaccine used, so it’s important to follow your veterinarian’s recommendations.

The biggest benefit of giving your pup a canine leptospirosis vaccine is that it prevents them from contracting this harmful and even deadly infectious disease. That, in and of itself, provides great peace of mind for pet parents.

“It is very difficult to control leptospirosis in your environment if you have a yard, as it is carried by wildlife,” says Dr. Wooten. “The best way to protect your dog against leptospirosis and leptospirosis symptoms is to have him receive the leptospirosis vaccine as a puppy, and then have him vaccinated annually after that.”

Another benefit of the lepto vaccine is that you can help prevent greater outbreaks in your home or area. Remember, leptospirosis is very contagious and is easily spread between dogs and even to humans.

What’s the downside? For many dogs, not much. One drawback associated with the leptospirosis vaccine is that, rarely, some dogs do experience some mild vaccine reactions.

Dr. Johnston says that, as with any vaccine, there may be mild side effects, such as:

• Soreness at the injection site
• Lethargy
• Temporary loss of appetite
• A mild fever

Serious adverse reactions are very rare, but they can occur. Pet parents should monitor their dog for any unusual reactions and consult their veterinarian if they have concerns, Dr. Johnston says.

“If you have spent any time searching the internet, then you will likely notice there is still a prevailing belief that the leptospirosis vaccine has a high reaction rate,” adds Dr. Wooten. “In the past, this was true—the vaccine seemed to cause adverse reactions in a number of dogs, including vomiting, loss of appetite, lethargy, and, sometimes, hives.”

Fortunately, she says, science has progressed, and the new lepto vaccine for dogs has a very low reaction rate.

Unlike rabies or parvovirus vaccines, the leptospirosis vaccine is currently not considered a “core vaccine” by the American Animal Hospital Association (AAHA). However, if you live in a hotspot or if your dog spends any amount of time outdoors or at a kennel, then the lepto vaccine can help keep your pet free from this disease and provide great peace of mind.

“Vaccination for the prevention of leptospirosis should be strongly considered for dogs in the United States, as this disease can be life-threatening and is zoonotic,” says Dr. Boronat. (A zoonotic disease is a disease or infection that can be transmitted naturally from animals to humans or from humans to animals.)

Dr. Johnston agrees, adding that vaccination not only protects your individual dog and the rest of your family, but also the community at large.

“These days, thanks to urban sprawl and fragmentation of wildlife areas, city dogs and dogs that live in purses are at risk, and the disease risk is growing,” Dr. Wooten says.

Lepto vaccine costs vary from clinic to clinic and depend on your location. Generally, you can expect to pay from $15–$50 for each shot.

Keep in mind that this vaccine requires a series of shots and routine boosters, so you’ll need to visit your veterinarian according to their recommended schedule to ensure the vaccine works to its full potential.

While taking care of our sweet canines means spoiling them with lots of cuddles and giving them plenty of attention, treats and proper training, it also means staying on top of their health—just like we do our own. This includes administering vaccines that help keep them in tip-top shape. When in doubt, speak to your veterinarian about your dog’s vaccination schedule.

Your vet will administer the lepto vaccine between your dog’s shoulder blades. It is a quick and easy shot that shouldn’t cause them much pain.

Dogs can get leptospirosis when they are exposed to Leptospira bacteria, which is spread through infected animals (typically through their urine or feces) and contaminated water, soil, or food. It is a zoonotic disease, meaning it can be spread from animals to humans or vice versa.

Wet conditions, heavy rainfall or flooding, and wildlife or rodent activity can increase leptospirosis exposure risk for dogs, as well as time spent at a kennel or dog park.

While leptospirosis used to be prevalent in rural areas, it has become increasingly common in urban areas as it is passed between unvaccinated pets. 

Symptoms of leptospirosis in dogs can vary, but they commonly include fever, lethargy, vomiting, diarrhea, muscle pain, and jaundice.

The most common underlying causes of the clinical signs associated with leptospirosis are kidney and liver dysfunction, but many organs are affected. In severe cases, lepto in dogs causes death.

The main benefit of the leptospirosis vaccine is that it helps protect your dog from this dangerous and potentially deadly bacterial infection. A secondary benefit is protecting other dogs by ensuring your pup doesn’t contract leptospirosis and pass the infection to other dogs. 

Your vet can weigh your dog’s exposure risk but it is hard to control their exposure to this bacteria since it’s carried by wildlife, other dogs, and can live in the environment, including your backyard.