Leptospirosis in Dogs

Despite many years of working in the medical field, I hadn’t heard of leptospirosis until recently when it suddenly was all over the news.  So you may be wondering what exactly is leptospirosis and why should I be concerned about it?

What is Leptospirosis?

Leptospirosis is a bacterial infection that can affect many different animals from various types of wildlife to dogs, and yes….even people!  The disease is not just caused by one specific strain of Leptospira, but by a myriad of different types within this genus of bacteria.  While Leptospira bacteria exist all over the world,  they are more common during periods of heavy rainfall.  Since we are in the midst of monsoon season here in Arizona, there has been a huge increase in reported cases of leptospirosis here.


Electron micrograph of Leptospira bacteria

I know, many of you have the misconception that Arizona is always dry.  I believed that too until I moved here.  But every summer, especially during July and August, we have monsoon season, where we get sudden and often violent rainstorms with lots of thunder and lightning.  In fact this past week, we’ve had a rainstorm almost every evening.  And you think we have a dry heat, right?  Well not now!  The past few days we’ve had humidity nearing 80%, so it feels like a sauna outdoors.  Hence, the warnings on the news.  Those ornery little bacteria are loving our weather right now, which plays havoc for animals and people alike.


‘Sorry for the technical jargon, but, let me explain exactly why you should be aware of leptospirosis, the various ways it can be spread, what the signs and symptoms are, the treatment, and what precautions you take to help prevent it.

Ways it can spread

One of the most common ways a dog can contract the bacteria is by coming in contact with anything that’s been contaminated by the urine of an infected animal, which can include other dogs, wildlife, rodents, etc.  So be especially vigilant when your dog is outside, don’t let him/her drink water from puddles, pools, etc.  Letting your dog go swimming in ponds and lakes is also another way they can come in contact with bacteria.  In fact, anywhere your dog goes outside, it’s possible that another animal has been there and peed on plants, dirt, or other objects.


Wild animals can carry around the bacteria and continue to deposit it into the environment for months or even years, without having symptoms themselves.

Cats and People

People can become infected too in the same ways their dogs can, and if your dog is carrying the bacteria it can also be transmitted to you and your family.  Fortunately, person to person spread of the disease is rare.


Cats are less likely to contract the disease, and oftentimes even if they do they seldom have any symptoms.  The most common way for a cat to contract leptospirosis is by hunting and eating infected rodents.  For more information on cats and leptospirosis, check out this article.

Signs and Symptoms

There can be a wide range of symptoms and some can be vague or hard to pin down.  In fact, sometimes there may be no visible symptoms whatsoever.  But things to watch out for include:

  • Decreased appetite
  • Muscle aches, pains and stiffness
  • Fever
  • Vomiting
  • Diarrhea
  • Red, swollen eyes
  • Difficulty breathing or coughing
  • Jaundice
  • In severe cases, even organ (kidney or liver) failure


It’s important to get your dog to a vet as soon as possible because the earlier treatment is started, the better.  In order to reach a diagnosis the vet will want to do lab work, blood tests, and get a urine sample.  Because the disease can potentially become quite severe, treatment may be started even before all of the tests are back, in order to decrease the severity of illness and the risk to other pets and people alike.



Vaccines are available to protect against the most common types of the Leptospira bacteria.  One such vaccine is called DHLPP ( the L is for Leptospira).  Check with your veterinarian to be sure if your pet has received this vaccination.  Part of the news programs I have seen are urging people to get their pets vaccinated as soon as possible if they have not already done so, due to the increase in cases of leptospirosis here in Arizona.  But if you live in any area where you’ve gotten a lot of rainfall lately, it’s important that you keep your pets vaccinated against this potentially deadly bacteria.

It’s important to keep in mind, though, that no vaccine can offer 100% protection, especially because there are so many different strains of the Leptospira bacteria.  But you can take extra precautions to minimize your pet’s exposure.  You can do your best to minimize your pet’s contact with potentially contaminated hazards such as stagnant water and wildlife.  Also be careful about allowing your dog to engage in outdoor activities such as field trials or hunting. Be sure to keep your dog’s vaccinations up to date and have the records handy, especially if you need to take him to an emergency vet.


Finally, if your pet is showing any signs or symptoms and you believe he/she may have been exposed to Leptospira, get them to the vet as soon as possible.  The sooner treatment begins, the better.

Until next time, keep your pets and yourself safe and healthy!


Leave a Reply

Your email address will not be published. Required fields are marked *