Leptospirosis: Should You Vaccinate Your Dog?

Many pet owners have recently called me to ask about the leptospirosis vaccine, wondering whether they should vaccinate their dogs against the disease. This is valid question, and it’s often debated amongst owners and veterinarians. The media often reports “outbreaks” of leptospirosis, but they leave out very important facts and statistics. My goal is to provide you with a better understanding of the disease to help you make the decision whether or not to vaccinate your pet.

What is Leptospirosis?
Leptospirosis is a bacteria called Leptospira interrogans, occurring worldwide in both domestic and wild animals. It can also be transmitted to humans. It is important, especially in regards to the vaccine, to note that there are over 200 named serovars (types) of leptospirosis.

How Is It Contracted?
It is generally spread through the infected urine of contaminated animals where it settles in water and soil. The virus can last in the environment for months. Generally, your pet becomes infected by drinking, swimming, or walking through infected water. Raccoons, skunks, squirrels, opossums, deer, rats and mice are all carriers. Cases of leptospirosis in cats are extremely rare.

Signs that Your Pet May be Infected
The most frustrating thing about leptospirosis is that signs may be vague and vary dramatically from pet to pet. Time between exposure to the bacteria and symptoms is typically five to 14 days, although it may take less or longer than 30 days for it to appear. In the early stages, dogs exhibit fever and lethargy. Symptoms may quickly progress to nausea, vomiting, diarrhea, decreased appetite, weakness, depression, joint stiffness, and muscle and abdominal pain. Your pet may exhibit none, one, or all of these symptoms. Later stages of the disease may cause increased thirst and urination (a sign of kidney disease) and even jaundice (a sign of liver disease).

How Do We Test for Leptospirosis?
To find out if your pet may be infected, we will take a blood sample to analyze antibody levels. Most labs require several days for test results to come back, so if there is a suspicion of leptospirosis, I usually recommend starting antibiotics right away.

Treating Leptospirosis
Treatment for leptospirosis should include the administration of the antibiotic doxycycline. Current recommendations by the ACVIM (American College of Veterinary Internal Medicine) recommend at least 2 weeks of medication. If your pet cannot receive oral medication due to vomiting or nausea, he should be started on an intravenous form of penicillin. Because this bacteria has a high prevalence for causing kidney failure, your pet may require intravenous fluids for several days. Prognosis is reported to be very good for those cases treated early.

What to do If Your Pet is Leptospirosis Positive
Because leptospirosis has potential transmission to humans, strict precautions should be taken when handling these animals. It can be transmitted via the urine, blood, or tissues. One should wear a gown and gloves and dispose of any waste appropriately. Your dog should not be allowed around other dogs until he is cleared of the infection.

Should You Vaccinate Your Pet?
It is most important to remember the vaccine does not provide 100% protection. Most leptospirosis vaccines administered as a single agent include four different serovars (types) of leptospirosis: grippotyphosa, pomona, icterohaemorragiae and canicola. Those vaccines that include a combination of the distemper/ parvovirus and leptospirosis usually only contain 2 types of leptospirosis. But here’s the catch: There are currently more than 200 types of leptospirosis named and probably many more unnamed. Many of the most recent outbreaks consist of serovars for which there is no vaccine.

So, which dogs should be vaccinated? Usually those that are in the “at- risk” population should receive the vaccine. The tricky part is defining who is the “at-risk” population. Typically, that may include any of the following:

• dogs living in an urban environment with a high population of rodents


• hunting dogs


• dogs off leash who frequently come into contact with stagnant pools of water or swim


• dogs who live in an area where multiple cases of leptospirosis have been reported and documented to be of the type which the vaccine covers

Why not vaccinate all dogs?
First vaccines are not benign treatments. They have been known to cause adverse reactions including hives, facial swelling, vomiting and in more severe cases anaphylaxis. Less reported (but still documented) is a correlation between vaccines and immune mediated hemolytic anemia. In general, small breed young pets (ages 1 to 3) have a higher risk of a vaccine reaction.

I believe it is important to evaluate each potential candidate for the vaccine on an individual basis. Circumstances, lifestyle, exposure risk, and vaccine reaction should all be taken into account. We are here to guide you through the decision process on whether your pet should be vaccinated and make appropriate recommendations. As always please feel free to contact us at the Worth Street Veterinary Center with any questions and we will be more than happy to clarify any concerns you have regarding this vaccine or any other pet related issue.

Julie Horton, DVM