Leptospirosis Cases Increasing. Should You Vaccinate?

I can't think of a more controversial vaccine than Leptospirosis.  Many people, especially certain breeders, think that it is dangerous and should never be given.  But the disease is potentially fatal and can be transmitted to humans.  So what should you as a pet owner do?

First, let's understand what "lepto" really is.  Here's a summary from the Centers For Disease Control website:  

Leptospirosis is a bacterial disease that affects humans and animals. It is caused by bacteria of the genus Leptospira. In humans, it can cause a wide range of symptoms, some of which may be mistaken for other diseases. Some infected persons, however, may have no symptoms at all.

Without treatment, Leptospirosis can lead to kidney damage, meningitis (inflammation of the membrane around the brain and spinal cord), liver failure, respiratory distress, and even death.

That sounds pretty serious, doesn't it?  And it really is.  While we don't see the disease often, it is very serious when it crops up.  Why don't we see it appear as frequently as it used to?  Because we've done such a good job of vaccinating against it.  But it's still out there, and in increasing numbers.

Again from the CDC's website:

The bacteria that cause leptospirosis are spread through the urine of infected animals, which can get into water or soil and can survive there for weeks to months. Many different kinds of wild and domestic animals carry the bacterium.

These can include, but are not limited to:

• Cattle
• Pigs
• Horses
• Dogs
• Rodents
• Wild animals

When these animals are infected, they may have no symptoms of the disease.

Infected animals may continue to excrete the bacteria into the environment continuously or every once in a while for a few months up to several years.

Humans can become infected through:

• Contact with urine (or other body fluids, except saliva) from infected animals.
• Contact with water, soil, or food contaminated with the urine of infected animals.

The bacteria can enter the body through skin or mucous membranes (eyes, nose, or mouth), especially if the skin is broken from a cut or scratch. Drinking contaminated water can also cause infection. Outbreaks of leptospirosis are usually caused by exposure to contaminated water, such as floodwaters. Person to person transmission is rare.

So anywhere that there are wild animals coming close to domesticated animals there is risk of lepto transmission.  If an infected wild animal urinates on the soil or in a water source, and your dog then drinks from that source or licks contaminated soil from their paws, there is a risk of infection.  And then if your dog becomes infected, it is a risk for anyone in your home to also contract the disease.

For my entire career (since 1997) there has been a perception among many pet owners and a LOT of breeders that the Leptospirosis vaccine was dangerous and should never be given.  I've even seen handouts from breeders that explicitly state that if a vet tries to give the lepto vaccine the new pet owner should find another vet.  This belief seems to stem from an impression that this particular vaccine has a significantly higher rate of serious reactions than any other vaccine.  Unfortunately these breeders are owners are very misinformed, even dangerously so.

A recent article in Veterinary Practice News highlights the increasing risk of lepto even in urban settings.  Here are some relevant quotes from that article

“Since 2013 in Florida, we have seen a 10-fold increase,” explains Carsten Bandt, DVM, Dipl. ACVECC, assistant professor of Emergency Medicine and Critical Care at the University of Florida College of Veterinary Medicine.

Although it was once most prevalent in regions with high annual rainfall and warm climates, current indications are that dogs with leptospirosis are found throughout the U.S.

“We are a tertiary center that sees two to three cases of leptospirosis a month in the warmer months,” said Julia Veir, DVM, Ph.D., of Colorado State University in Ft. Collins. “Our patients come from southern Wyoming and across the front range, the area from Denver north to Ft. Collins.”

“It is a bacterium that is spread from the urine of mammalian species like raccoons, mice and rats,” Goldstein said. “If a dog licks a puddle on a sidewalk, or walks in wet grass or in parks where wildlife would urinate, they can ingest the bacteria.”

“It is very rare to see a dog who was vaccinated get the disease,” Goldstein says. The first dose is two shots followed by one shot each year.

“The vaccination is effective against the four serovars of leptospirosis and may provide some cross protection against other serovars,” Dr. Harkin said.

It should be apparent that this is still a serious disease, and one that is actually increasing in incidence in various parts of the country.  Virtually all dogs are at risk for the disease, and there is no way to tell whether or not a pet is being exposed when they contact water or wet soil.  With this information in mind it should be easy to see the rationale for prevention.

But what about the often-touted idea of the vaccine causing horrible reactions?  Is it worth that risk?

This idea has no data to support it.  In fact, if you find anyone who states this as "fact", I challenge them to provide actual objective proof that the vaccine is more reactive than any other.  ALL vaccines carry some risk of causing a reaction, and rarely is that reaction truly life-threatening.  I've seen two different studies that have looked at vaccine reaction rates, and both of them showed no significant difference when comparing Leptospirosis vaccines to other vaccines.  "Well, I've been breeding for 25 years and I've seen plenty of bad reactions" is a subjective, anecdotal assessment, and is not actually any proof that would stand up in science or a court of law.  In order to prove a statement like "lepto vaccines are highly likely to cause bad reactions" you need to have numbers and statistics.  Not only does that data not exist, but the times it's been examined the numbers have actually shown that it is no more reactive than any other vaccine.

It's also important to note that there are several companies that make animal vaccines, and each company's vaccine is slightly different.  One company's vaccines may have a higher reaction rate than another company's.  In fact, my practice revised our vaccines in 2014, and the number one criterion we looked at was the reaction rate between manufacturers.  That data made us change the brand of some vaccines.  It's impossible to make a blanket statement "all lepto vaccines are reactive" when the rate of reaction varies depending on the brand.

So a breeder tells you never to give lepto because in their 25 years of experience this vaccine will almost always cause serious reactions.  Well, if we want to stick to subjective information, I can clearly state that I've been practicing for 18 years and in the veterinary field for 32 years, and I haven't seen lepto cause significantly more reactions than other vaccines.  I rarely seen vaccine reactions at all, and when I have it's to pretty much any vaccine on the market.  Lepto doesn't jump out to me as a dangerous vaccine.  

Now you have a choice....take the opinion of someone who has been breeding dogs for several decades, or take the opinion of someone with a medical degree and access to scientific journals who has been in the heart of veterinary medicine for the same amount of time.  Which opinion do you think is more likely to be informed and accurate?

Here's the bottom line for me.  Leptospirosis cases decreased after we started vaccinating for it.  In the last 20 years as we've seen an unfounded opinion that the vaccine is a problem, and therefore fewer pets are being vaccinated, we've seen a steady increase in lepto cases.  This is made worse as the population has expanded into previously rural areas and wild animals have adapted to suburban and urban life, bringing their diseases into closer contact with humans and our pets.  In the article above you can see that cases have increased 10-fold in just a few years.  We have a safe, effective vaccine that is no more dangerous than any other vaccine.  I strongly believe that this is an essential vaccine, and unless a dog has a significant medical reason that makes them unable to receive it, all dogs should have it included as part of their regular preventative care.  

And yes, my dogs are vaccinated for it.

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