Setting the Facts Straight about Leptospirosis

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Have you discussed leptospirosis with your clients? Do you know if your canine patients could be exposed to this infection? Do you have the information you need to help your clients make an informed decision about the risks and benefits of vaccination in your location?

A lot of misinformation exists regarding leptospirosis. Following are answers to your—and your clients’—frequently asked questions.

You have asked…

Why should my clients be aware of leptospirosis?

Leptospirosis can cause acute renal failure in dogs. Some may recover after prolonged intensive care in the hospital, while others may not survive  or survive with permanent renal function impairment. Leptospirosis can also cause liver damage, uveitis, respiratory disease, vasculitis, and bleeding disorders. In addition, because leptospirosis is a zoonotic disease,  family members, the veterinary healthcare team, and other animals are at risk for infection.

Is leptospirosis really a problem in my area?

Leptospirosis is a global disease and is likely present throughout most of the United States (except for true desert regions). It is more prevalent in warm, wet, and humid climates. Most dogs are exposed to leptospirosis in environments contaminated by urine of wild-animal hosts, including raccoons, opossums, mice, voles, rats, skunks, squirrels, deer, and foxes.

We have never diagnosed leptospirosis in my clinic―why should we worry about it?

Until they start testing for leptospirosis, veterinarians are often unaware that it is present in their area. Leptospirosis testing is important in dogs with acute renal failure, unexplained polyuria/polydipsia, cholestatic liver disease, pulmonary interstitial disease, or vasculitis. It is also important to perform both acute and convalescent titers when testing for leptospirosis with the microscopic agglutination test. PCR tests are also available for testing urine or blood in acutely infected dogs. Unless using the right test at the right time with the right patient, it’s possible to miss the disease. If unsure about the presence of leptospirosis in a local area, confirm with local colleagues, specialists, and referral hospitals.

Your clients have asked…

I own a small-breed dog that only goes outside to urinate and defecate. How could she be exposed to leptospirosis?

Leptospirosis is not limited to large-breed or outdoor dogs. If a dog goes outside, she could be exposed— all it takes is contact with one wild animal’s contaminated urine. If you  see squirrels, skunks, opossums, raccoons, mice, voles, deer, or foxes in your neighborhood, any of these animals could be spreading the infection.

Should I be concerned about the side effects of the leptospirosis vaccine?

Older vaccines against leptospirosis contained proteins that sometimes caused a reaction in dogs. The reactions were not always serious, but owners were still concerned, and veterinarians understood those concerns. Fortunately,  newer vaccines result in fewer reactions. Our practice recommends that the leptospirosis vaccine be given separately from other vaccines.

Do the leptospirosis vaccines really work? I have heard they only protect for a few months and have to be repeated frequently.

Some excellent studies have shown that the vaccines protect for at least one year.1,2 Our practice recommends a yearly booster after the initial course of vaccines. We also recommend vaccines that protect against 4 strains of leptospirosis, rather than older vaccines that only protected against 2 strains.

What happens if my dog is not vaccinated and gets sick with leptospirosis?  Is it treatable?

There are many possibilities, from mild signs you may not even notice to sudden death. Most dogs that get sick with leptospirosis will develop kidney failure or liver damage. Sometimes the kidney failure is severe enough that dialysis is required. Leptospirosis is treated with antibiotics, but with severe infections, significant organ damage may occur before antibiotics can clear the infection. Leptospirosis can also damage the eyes, lungs, and blood vessels, causing unusual signs that can be difficult to diagnose.

You can help your clients make educated decisions by being aware of the disease, testing appropriately, and staying informed about the risks and benefits of vaccination. 

References Show

Suggested Reading

2010 ACVIM small animal consensus statement on leptospirosis: diagnosis, epidemiology, treatment, and prevention. Sykes JE, Hartmann K, Lunn KF, Moore GE, Stoddard RA, Goldstein RE. J Vet Intern Med 25:1-13, 2011.


1. Onset and duration of protective immunity against clinical disease and renal carriage in dogs provided by a bivalent inactivated leptospirosis vaccine. Minke JM, Bey R, Tronel JP, et al. Vet Microbiol 137:137-145, 2009.

2. Duration of immunity in dogs vaccinated against leptospirosis with a bivalent inactivated vaccine. Klaasen HL, Molkenboer MJ, Brijenhoek MP, et al. Vet Microbiol 95:121-132, 2003

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