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What you need to know about Leptospirosis

I had no idea that we were smack-dab in the middle of an area that has one of the highest…

I had no idea that we were smack-dab in the middle of an area that has one of the highest predicted probabilities for canine leptospirosis in the United States! Did you? And if you’re like me, you are really just beginning to understand the “lepto” disease. What is it? Why is it important? Is your dog protected?

For years, the Leptospirosis vaccination was kind-of “hidden” in what was commonly known only as “the Distemper vaccination”, or DHLPP. As part of our dog’s core vaccinations, did we really understand what all those letters stood for? DHLPP stands for Distemper, Hepatitis (CAV-2), Leptospirosis, Parainfluenza, Parvovirus. I admit, I only knew that the D was for distemper and one of the P’s was for parvo. I have the feeling that I was not alone in this notion. Now the core vaccination is sometimes offered as “DHPP”, and the Leptospirosis vaccine – the “L” – is available singularly.

Just a few years back, I recall my Vet asking if I wanted Rex to have the Leptospirosis vaccination. I remember thinking, “What in the world is he talking about?” I had never been asked that before. In my eyes, it’s like this disease just popped up out of nowhere! Unbeknownst to me, Rex was only getting the DHPP as his 3-year Distemper vaccination. Somewhere along the line, his DHLPP vaccination turned into a DHPP, but I had not been informed. I didn’t thoroughly understand it then, and I didn’t get the additional vaccination. I wanted to do some more research on my own before giving it to Rex.

What is Leptospirosis and how do dogs become infected?

Leptospirosis, as my vet explained, is a disease found in the urine of some wildlife. If your dog encounters the infected urine, he could become sick. When this happens, Leptospires penetrate the skin and move through the bloodstream. It literally spreads throughout the entire body, infecting and damaging major organs, often causing acute renal failure. Dogs generally come in contact with the bacteria in wet areas… puddles, mud, while swimming, or drinking. It’s more prevalent in areas with high annual rainfall, but can be found anywhere, even in dry soil. As you can see, there are definitely places where it is more likely that your dog will come in contact with the lepto bacteria, but nowhere is totally free of it.

There is a lot of information online about how animals become infected with the disease, but little regarding where the bacteria came from or how it originated. That’s what I wanted to know. I learned that “Leptospires” are actually naturally occurring bacteria microorganisms that evolve just like any other life form, and live in the renal tubes and/or genital tracts of all different kinds of host animals. Animals typically contract the bacteria from their mother at birth. Leptospirosis was first “described” by a physician in 1886, but not formally understood or “named” until the early 1900’s. In 1933, it was reported that one strain specifically infected dogs: the Leptospira Canicola, and that’s when its significance to the veterinarian community became a factor.

Pretty much any animal can be a carrier: Cattle, sheep, horses, and pigs, etc.. In our area, we see leptospirosis in rats, mice, moles, raccoons, opossums, skunks, some fox, deer and dogs. The host animal may only be a “carrier” of the disease, never manifesting symptoms. The host may not ever become ill and may (pathogenic) or may not (saprophytic) pass along the bacteria in their urine. I know… kind of puzzling, but factual.

What are the symptoms of Leptospirosis in dogs?

Dogs can begin showing signs of leptospirosis a soon as a couple of days after they have been exposed. The symptoms are similar to so many other diseases and may vary: lack of appetite, vomiting, stomach discomfort, shivering, little desire to move around due to either weakness or stiffness, diarrhea, fever, and others. Since many of the signs are so ambiguous, it’s best to visit the veterinary without delay. It will be necessary to start antibiotic therapy just as soon as possible. Leptospirosis can be fatal if it is not caught soon enough.

Here’s a big kicker too… If you don’t identify and treat Leptospirosis to minimize the risk, you – yes you, human – can get it too. Leptospirosis transmission to humans is possible. It’s zoonotic. Precautions, like frequent hand washing, and wearing rubber gloves when handling your pet, are recommended. Areas where your dog has maybe vomited or left waste should be disinfected to prevent spread to people and other pets.


What is the Leptospirosis vaccine? As mentioned, the Leptospirosis vaccine was once a part of the core vaccination protocol. The initial vaccine was developed somewhere around 1960 but was not terribly effective at preventing the disease. I am guessing its inadequacy could be one reason it was dropped from the core/distemper vaccination. It was not until around 2003 that it was discovered that an inactivated vaccination, followed by a booster, caused a much better immune response. However, this combination is only effective for one year, whereas the distemper vaccination is an every 3-year injection… yet another reason to remove it from the core vaccination.

Many believe the Leptospirosis vaccination is more of a “situational” type of vaccine. Dogs that live in the country or near a lot of wildlife would definitely need it, but perhaps dogs who live in the city – predominantly in the home – do not necessarily need to be vaccinated. Because of all the animals that live alongside us in the suburbs and city – mice, raccoons, rats – I find that rationalization to be questionable.

The Leptospirosis vaccination is required by canine guests visiting Holiday Barn Pet Resorts. We respect the unique medical needs of each pet and will accept modifications to this requirement if documented and signed by your veterinarian.

Leptospirosis in Cats

Even though recent studies suggest that cats may actually have an innate resistance to the disease, cats can become infected with leptospirosis. Cases are very rare. My guess is because so many cats live indoors and do not come in contact with the bacteria. Outdoor cats, especially those that hunt disease-carrying rats and other rodents are certainly vulnerable. Cats can also get the disease from their canine sibling. So your dog could actually bring it home to your cat that never leaves the house. There is currently no vaccine for cats.


There are some in the veterinary field that are adamantly opposed to giving the annual lepto vaccination, particularly holistic veterinaries. You see, the vaccination is not technically a “vaccine” – something that prevents the infection, but rather the injection of a lepto bacterin – a method of injecting with the bacterin itself which boosts the body’s own natural immunity. It’s a common practice, but it only decreases the severity of the disease. The argument is that since the vaccination only causes the symptoms to be less severe, your pet can be very ill before you even notice it. Many of the veterinarians opposed to the vaccination believe that that if your dog has good nutrition, and a strong constitution, they are naturally resistant to the disease.

United States Predictions

I mentioned in the beginning that we are in the middle of one of the areas with the highest predicted probability for leptospirosis in the US. The following, published in The Veterinary Journal, is where I obtained that information:

Counties with the highest predicted probabilities for canine leptospirosis in the USA.

What can you do?

Use caution to avoid contamination. Here are a few suggestions for Leptospirosis prevention:

• Don’t let your dog drink from standing water.
• Keep rat and mice problems under control.
• Don’t let your dog play in pools of water resulting from flooding.
• Keep your dog from licking his/her paws after walking in areas that may be contaminated.
• Don’t allow your dog to wallow in a mud puddle, no matter how amusing it is.
• Keep your dog from chasing or otherwise coming in contact with common raccoons, skunks, and other area wildlife.

I am sure you have a veterinary that you trust. Please defer to their expertise when deciding whether or not to vaccinate your dog from Leptospirosis.

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