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What is lepto, how is it spread, and how does it make dogs (and people) sick?
Leptospirosis is caused by spirochete bacteria in the genus Leptospira. There are several species of lepto, each of which has several subtypes known as serovars. Each lepto serovar generally has a preferred host to which it is adapted. These so-called reservoir hosts can spread the bacteria but often do not develop illness from them. Other species, unfortunately, are not so lucky. Reservoir species spread lepto into the environment. In the Bay Area the most common reservoir species are all familiar players: rats, mice, skunks, raccoons, and opossums top the list.
Lepto is spread through urine. When an infected animal urinates in or near a body of water, that body of water becomes contaminated. The body of water can be large (a stream or lake) or small — a tiny puddle or even a drop of water on a blade of grass can suffice. When a dog swims in, drinks, or steps in the body of water there is a risk of infection.
In dogs, lepto infects the bloodstream, the liver, and the kidneys. It can cause blood cell problems, liver failure, and kidney failure. Vomiting and diarrhea are common early symptoms. Untreated lepto often is fatal in dogs.
That news is bad enough on its own, but unfortunately it gets even worse. Infected dogs can spread lepto through their urine. Humans also can contract leptospirosis. This means that dogs infected with lepto have the potential to spread the deadly disease to their families.
Can lepto be treated?
Antibiotics often can cure lepto, especially if they are started early in the infection. However, treatment failures can occur if treatment is delayed, or if lepto is not recognized as the cause of the dog’s illness.
Why has lepto been in the news?
Lepto loves water, and as Bay Area residents will recall, last winter was the wettest in California history. That meant that there were safe harbors for lepto all over. At least a dozen Bay Area dogs were diagnosed with lepto; this reportedly included some dogs that had not left their owners’ yards (remember that the reservoir hosts are everywhere in the Bay Area). The majority of the dogs diagnosed with lepto last winter reportedly did not survive.
What can we expect this year?
Although this winter probably will not be as wet as the last one, there is bad news. Dr. Richard Goldstein, chief medical officer of the Animal Medical Center in New York and a highly regarded lepto expert, has stated that lepto outbreaks tend to be worst the year after heavy rains. That means that this winter could be even more hazardous than the last one.
Is there any good news?
Yes. Although lepto is common, dangerous to dogs, and potentially transmissible to humans, it generally is preventable with a vaccine. The vaccine protects against the most common lepto serovars. Initially, dogs receive a series of two vaccines, approximately three weeks apart. Annual booster vaccines are used to maintain protection.
But doesn’t the lepto vaccine cause adverse reactions?
Historically the lepto vaccine has had a bad reputation for causing adverse reactions in dogs. Happily, modern vaccines have greatly reduced this concern.
The original lepto vaccines were quite crude. The bacteria would be grown in a culture broth that contained nutrients and all of the the things that lepto need to live and reproduce. The entire mixture would then be subjected to heat or chemical treatment to inactivate the bacteria, and then, essentially, the entire mixture would be injected into dogs.
It was the so-called exogenous materials — the culture broth — that caused the reactions that made the lepto vaccine notorious. The active portion of the vaccine itself was not especially dangerous.
Vaccines have changed a great deal since that time, and modern vaccines now are filtered and purified to reduce the risk of adverse reactions. San Bruno Pet Hospital uses the most modern and pure lepto vaccine available. Our vaccine is ultra-purified to contain the fewest exogenous materials of any vaccine that ever has been made. This makes our vaccine the safest lepto vaccine that ever has been available.
Leptospirosis is endemic in the Bay Area, and the threat it poses is real. Please talk to one of our vets about whether the vaccine is right for your dog.
By Dr. Eric Barchas, DVM
Medical Director of San Bruno Pet Hospital