Does your dog need a leptospirosis vaccine?

When I first started making house calls, I debated whether or not to offer the vaccine against Leptospirosis. I didn’t routinely carry it, but for the small number of dogs who needed it, I would order it and vaccinate them.
Well, I decided to just start carrying it. There are many pros and cons to vaccinating your dog for this disease. I’ll present both sides in detail, and let you decide.

Reasons FOR vaccination:
1 – The bacteria may be more prevalent than we think, putting more animals at risk.
2 – Raccoons and rodents, carriers of the disease via their urine, are pretty much everywhere in the suburbs, possibly exposing dogs to this bacteria.
3 – The disease can be fatal (causes liver and kidney failure), and treatment is costly. Infected dogs can transmit the disease to humans.

Reasons AGAINST vaccination:
1- Potential risk of vaccine reaction.
2- Risk of infection is questionable, with it being rarely diagnosed.
3 – Vaccine may not offer complete protection against the serovar your dog meets.

Here’s what that means:
To start, what is Leptospirosis (AKA Lepto)? It’s a spiral shaped bacteria that is most often associated with standing water. The theory is, wildlife (specifically raccoons) who carry this bacteria urinate in the water. The bacteria can penetrate skin, so if your dog swims, jumps in, or drinks the water, he or she can acquire the bacteria. That’s what I learned in school.
Now we’re getting reports nationwide of dogs who have no access to standing water getting Lepto. Theory is that wildlife urine can be anywhere, not just in water, to deliver the bacteria. Apparently the rat peeing in the dry gutter, or the raccoon peeing in the dry leaves, can do the trick.  That makes a lot more dogs seemingly at risk!
Lepto in dogs makes them very sick, and can be fatal if not treated aggressively. Treatment consists of IV fluid therapy and days in a hospital on IV antibiotics. We try to keep the kidneys and liver happy and out of complete failure while we kill off the offending bacteria. This treatment often costs thousands of dollars.

golden retriever, cancer, hemangiosarcoma, sick dog

Golden retriever who isn’t feeling well – is it Lepto?

To boot, diagnosing this disease is tough! There really is no great Lepto test. Kinda like testing for tick disease, the traditional Lepto test shows exposure to the disease. If a dog is acutely ill, the test can be a false negative. If the dog ran into the bacteria, and his immune system successfully fought it off a while ago, you can get a false positive. What makes it worse – these tests are expensive and take days to get results, while you have a dog trying to die in your hospital! A new test is emerging, called PCR, which detects small amounts of Leptospirosis, but is only available at select laboratories. Still, it’s a better option, although rather pricey as well. You can sometimes get lucky and find the bacteria microscopically in the urine, which gives you an instant diagnosis. I’ve never been that lucky.

How common is this disease? Remember, getting an actual diagnosis is tricky, so a dog may be a “Lepto suspect” but never be confirmed. We treat it like a Lepto case and he gets better – who knows what it was really? In my career, I’ve had about 30 Lepto suspects, but only one that I could confirm, often because the owners would not let me perform the test (cost, timing, etc). The final kicker- it’s a disease that people can get! Because the bacteria can penetrate skin, full protective gear must be worn by all parties interacting with the dog in the hospital – even if he’s a “suspect.”. Yep, it causes kidney and liver failure in people too.

This disease sounds awful! Why not vaccinate every dog?

For decades, the Lepto vaccine has been associated with the highest rate of vaccine reactions among the various types of vaccine. Some reactions are minor, others are life threatening. No way to tell which dogs will react (although small breeds are predisposed) until we have swollen, or worse, sick dog in front of us. However, new data is coming out that it isn’t the Lepto vaccine per se that is causing reactions, but it’s more a function of the total number of vaccines going into a dog in one visit. Lepto was associated with increased reaction rates, because  it’s often the additional vaccine, the “straw that broke the camel’s back.” The reaction rate is less than 3%, so still very low, but it is higher than other vaccinations.
Also, there are SEVEN different subtypes, or serovars, of Lepto. The Lepto vaccine only covers two -four of them, depending on manufacturer. Guess which three serovars are on the rise? Yep, the three not in any vaccine. Some protection against these is still afforded by the vaccine, but it won’t completely prevent your dog from getting sick.
Finally, the shot lasts one year, so for your dog to be protected, he or she would need to be vaccinated every year. I often recommend three-year vaccines on DHPP/ Distemper combo and Rabies, but there’s no choice with this one.

Bottom line – every dog is an individual. Yes, Leptospirosis is a horrible disease. While we vets may see cases that are “suspects” we rarely get a confirmed case. How widespread is it? No one really knows. Is it out there? Absolutely! I like to give all the facts, and then you and your vet can decide what is best for YOUR dog based on the pros and cons.

Posted in Internal Medicine, Vaccines.


  1. Thank you for writing this article. Well written. I have a 11.8lb chi mix who went to the vet today for Lepto, Lime, and Bordetella. She was fine all afternoon- now a little lethargic and very sensitive at injection site. No throwing up or bowels yet thank goodness. Makes me wonder was it this shot? Or all 3 at once?? Hard to know!

    • A shot that can kill your dog. All you have to do is keep pet out of places that Lepto can doesn’t even have a guarantee to protect against Lepto. Lyme isn’t needed either . Poisons put on for fleas aren’t needed either. Those are pesticides!! Rabie shots aren’t needed yearly!!! Our pets are being overvaccinated and it’s killing them! Do the research. Check out the website ‘protect the pets’ and see!!! Hope your pup is ok.

  2. Thank you for presenting both sides — too often things are so biased that it’s hard to make an informed decision. Your article was clearly written — a breath of fresh air on the internet!

  3. I also thank you for presenting both sides. My vet, who is also degreed in bio-chemistry, has been shying away from over-vaccinating for a while. They opted to skip bordetella and lepto vaccines back in the spring for my two dogs and I went along with it, particularly not knowing if lepto was particularly effective.
    A month ago, one of my dogs got very sick. Symptoms in a dog can seem quite generic and it was initially thought he had a GI disorder. Then, by accident, blasto showed up on a thoracic radiograph. We began treatment for blasto, the symptoms accelerated, and my boy was dead eight days later.
    In retrospect, I think the discovery of blasto probably diverted attention away from the symptoms he was presenting, which were classic lepto. Also, the area we live in is highly friendly to lepto.
    I’ll never know, but my gut feeling is that my dog died of untreated lepto while being treated for blasto. Both diseases like similar environments.

    • I’m so sorry about your dog. Blasto is a terrible disease as well. It’s easy to beat ourselves up, second guess, do the “what-ifs.” (If self-induced emotional torture were an olympic event, I’d be champion!) Just know that you did your best with the information you had at the time. And even if you had vaccinated, would it have made a difference? Impossible to say. I’m very sorry for your loss.

  4. Thanks for pointing out that the pet must be vaccinated every year so that he will be protected. I will keep that in mind since we will be adopting a dog next month as per the request of my youngest for her birthday. It will be our first time, so it is important to know about these things.

  5. My five year old male chihuahua is due for a leptospirosis booster. I worry that it’s unnecessary and putting my dog at risk for over vaccinations. He’s about seven pounds and I don’t know what to do. He has a fenced in yard, and I take him on walks on a nature path. We live in the suburbs, but our neighborhood is considered a reserve with lots of trees and a lake. Can you advise me about his upcoming shot? He will also get his rabies shot at the same time. Thank-you.

  6. Thank you – I wish I would have read your article sooner. We lost our robust, 8-year old Standard Poodle Riley after he received his second Lepto shot. He became very, very ill 3 days after the shot. We tried everything to save him – but he went into kidney failure. I have no doubt in my mind the shot caused his death. I will NEVER give this shot to another one of my animals.

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