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Leptospirosis AKA “Lepto”

Leptospirosis Vaccine In DogsWhen 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 in detail, and let you decide.

Reasons FOR vaccination:
1 – The bacteria may be more prevalent than we think?
2 – Raccoons and rodents are pretty much everywhere in the suburbs, possibly exposing dogs to this bacteria.
3 – The disease can be fatal, 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 water getting Lepto. Theory is that wildlife urine can be anywhere, not just in water, to deliver the bacteria. That makes a lot more dogs seemingly at risk!
Lepto in dogs makes them very sick, and can be fatal (treatment is a specific antibiotic that kills the bacteria). If not treated aggressively, (to the tune of about $2,000) the dog will succumb to liver and/or kidney failure.

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 little bit ago, you can get a false positive. A new test is emerging, called PCR, which detects small amounts of Leptospirosis, but is only available at select laboratories. You can sometimes get lucky and find the bacteria 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 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.

To boot, 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. Yep, it causes kidney and liver failure in people too.

Why not vaccinate every dog? For decades, the Lepto vaccine has been associated with the highest rate of vaccine reactions. 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 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 number of total vaccines going into a dog in one visit. Lepto was associated with increased reactions, as 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 four of them. Guess which three serovars are on the rise? Yep, the three not in the 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. You all know pushing vaccines isn’t my game. I like to give all the facts, and then you and your vet can decide what is best for YOUR dog.

Web-DVM guest blogger Dr. Karen Louis is a practicing small animal veterinarian.  See more of her articles at her blog at

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