Angry Vet On Leptospirosis

by Dr. Robert Foley, DVM

As a sad reminder of the dangers and reality of leptospirosis, we had two cases of acute renal failure in otherwise healthy young dogs. 

One of these dog’s kidneys completely shut down and would not respond to treatment. She was euthanized humanely. The other dog, I am pleased to report has responded, and is now home and expected to make a full recovery.

This post is dedicated to Sandy, our unfortunate patient who died far too young:

A differential that is high on the list when an acute renal patient presents is leptospirosis.

Leptospirosis is a bacteria that affects primarily dogs that drink water contaminated with the urine from rodents and mammals like raccoons.

Once infected, your dog can become sick, sometimes gravely sick, with kidney and/or liver failure.

Symptoms can include drinking and urinating excessively progressing to scant or no urine production, vomiting, anorexia, and lethargy. Response to antibiotic therapy is possible if instituted early.  If there is resistance to antibiotics or if antibiotics are instituted too late, progressive organ failure can lead to death. It must also be noted that leptospirosis can be transmitted from pets to humans.

Our recent exposure to this bacteria re-raises some of the questions with which we at Angryvet frequently wrestle. 

While we do carry the leptospirosis vaccination, we don’t recommend it as one of our core vaccines. We offer it to people whose pets have exposure to wildlife and who feel that the benefits of the vaccination outweigh the risks.

The leptospirosa vaccination typically contains four (at least) serovars/strains. 

Scanning electron micrograph of Leptospira interrogans serovar copenhageni.
Image: Medical Books Online

The problem is that there are hundreds of serovars, and immunity against one serovar does not necessarily predict immunity against another.

In theory, the strains chosen are strains that are known to occur in a local area. This is typical of the flu shot given to people where scientists try and predict which flu strain will be out during a particular season and subsequently which strain(s) will be put into the vaccination. These predictions often fall short in providing protective immunity.

Canine leptospirosis vaccinations are not changed with such frequency, so we can expect vaccination immunity to frequently fall short.

Also, predictably, the immunity that is obtained to any strain is fleeting (sometimes 9 months or less). This is because the immunity from bacterial vaccinations is different from the immunity from viral vaccinations. It necessitates the activation of various cell-mediated immunity pathways (natural killer cells, etc.) and not the humoral immunity (antibody production) activated by viral vaccines.

Also, and perhaps most importantly, the leptospirosis vaccination is most frequently associated (anecdotally) with vaccine reactions in the patient.  

These reactions are sometimes severe and can necessitate emergency treatment.  Reports of death, while rare, can occur.

One of our patients, the one who died, tested NEGATIVE for leptospirosis.  

A negative test does not guarantee that he did not have it. The tests can provide false negatives. Interestingly, this dog was vaccinated against leptospirosis recently. This means that either the vaccination failed or that her renal failure was caused by something else. Contaminated dog food from China remains a distinct possibility.

The other dog, who tested POSITIVE for the disease, was not vaccinated.  

A positive test does not guarantee that she had an active leptospirosis infection that triggered her renal failure. The test can also show false positives. The likely scenario is that leptospirosis was indeed responsible for her renal and hepatic failure. She is, fortunately, making a nice recovery.

With all of that said, vaccinations can be very effective biological weapons against disease.  When one determines whether to use a particular vaccine they should ask …
  1. How effective is the vaccine?
  2. How safe is the vaccine?
  3. How long lasting is the immunity that is conferred by the vaccine?
  4. How likely is it that the animal will be exposed to the disease with which we are concerned within her environment?.

Leptospirosis is a very difficult vaccination to weigh in on. 

In some heavily endemic areas, where outbreaks are frequent, recommending the vaccine may be much more clear-cut. Conversely, if an animal is paper trained or is indoors (or mostly indoors), the decision to not vaccinate may be easier.  It has been suggested that certain breeds like Dachshunds are more susceptible to reactions.

In my particular area of Long Island and Queens we do see some outbreaks. 

We offer the vaccine to new patients and provide the information to the owners as to the safety and efficacy of the vaccine to allow people to make their own decision for their own pet.

I do not personally vaccinate my dogs against leptospirosis.

As data changes so too may our recommendations…


Articles by Angry Vet: 
Really Angry Vet: Winston's First Seizure  
Ruptured Cruciate Ligaments And Early Spay And Neuter  
Itching For A Diagnosis
Angry Vet On Ear Infections (Part I) 
Angry Vet On Ear Infections (Part II)


  1. Sounds to me like the flu shot for prevents some flu strains but not all, so it too is a crap shoot which mom doesn't buy in to. We got the Lepto vaccine a few times but then decided it was not really something we needed.

    1. Well, with the level of exposure our guys have to wildlife and water sources, we still do vaccinate, even though hesitantly. Still seems to be the lesser of the evil for us.

  2. I live in Long Island New York. I happen to live right next to a small piece 100 by 100 land run off which is taken over by weeds and looks like a jungle. Seems like there are a lot of rodents in there. Anyway my dog been grabbing the possums and killing them. He's not eating them but I think he is playing with them and pawing at them while they play dead and killing them. He a very thick boned Tibetan Mastiff so I guess his weight of his paw is liking them. He can be rough. He had his rabies shot and distemper 2 years ago so that should be good but the vet nurse said I should think about getting him the Leptospirosis shot because if he drinks their urine he can catch rappies or something. Should i worry about getting Lepto?

    1. Lepto is transmitted by urine; gets into water outside as well (ponds, puddles ...). If your dog gets in contact with either urine through pray kills, or contaminated water, then there is a risk of exposure, yes.

      Before vaccinating, though, do find out which strains do you have where you live. The vaccines don't cover all of them and if the strain isn't included in the vaccine vaccinating is pointless because there is no cross-immunity between the different strains.

      We always vaccinated for lepto where we lived but here, in our new location, neither of the two strains present up here is included in any of the vaccines. So we won't vaccinate any more as there is no point.

  3. My perfectly healthy dog who is not even 2 is fighting for her life here in TX. We just received the positive result and she is in renal failure. We haven't given up just yet. Are there any specialists out there or more literature on how we can beat this??

    1. So sorry about your dog. Since he's been healthy, I wish he makes it through.

      Leptospira interrogans is sensitive to penicillin, a readily available antibiotic. After penicillin has been used to stop leptospire reproduction and limit bloodstream infection, tetracycline derivatives (such as doxycycline) are used to clear leptospires from the kidneys.

      Intravenous fluids are crucial to support blood flow through the damaged kidneys so that recovery is possible. Any areas at home that have been contaminated with urine should be disinfected with an iodine-based product and gloves should be worn when cleaning any urine. Prognosis is guarded depending on the extent of organ damage.


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