Leptospirosis In Dogs And People
Leptospirosis gets its name from lepto, meaning slender, and spiro, from spire, meaning “coil.” The genus of these spiral bacteria includes the leptospires or spirochetes.
Leptospirosis, or “lepto,” as it is more-commonly shortened to, is a disease of the kidneys of mammals. There are over 200 serovars, or serologically-individualized varieties of the organism worldwide. Each different serovar typically infects only one or two species of mammals.
Leptospirosis is the most widespread zoonotic disease in the world. In some parts of Hawaii, where the natural reservoir host is the wild pig, streams are marked with warnings to swim at one’s own risk because of the extent of infection.
Swimming, or just stepping in a puddle, is the best way for you, or your dog, to contract leptospirosis. These organisms can live for up to weeks or even months in warm, moist soil, and come from an infected animal’s urine. Thus, if a person, wolf, coyote, possum, coon, skunk, rodent, pig or cow contaminates an area with leptospires, the next mammal along, if susceptible, may become infected.
I specified “if susceptible” because dogs are commonly vaccinated against leptospirosis and, if vaccinated at least annually, may have protection against the organism.
“May” is an important word in that sentence because protection against a specific serovar is conferred only by vaccination against that serovar. In the United States dogs are typically vaccinated with two, three or four common serovars, depending on the vaccine your pet’s doctor uses.
On the other hand, if your dog has previously had a reaction problem at vaccination time, veterinarians are quick to blame the lepto component. Bacterins, vaccines designed to immunize against bacterial diseases, are commonly associated with adverse responses. Those can include pain, swelling, hives and breathing problems after vaccination.
Also, some practitioners don’t vaccinate against leptospirosis because they perceive the threat to be low. While it’s true that some areas of the country enjoy lower leptospirosis rates of infection, infection abounds in many parts of the country, including the coastal northeastern US, in addition to the more-obvious southern states and Hawaii.
What happens if your dog becomes ill (the incidence of the disease in cats is extremely low)? The first signs may be very non-specific, what veterinarians frequently call, ADR or “ain’t doin’ right.” Owners may report lethargy, loss of appetite and stiffness. Such signs could be included in the presenting history of hundreds of conditions.
Laboratory evidence of kidney disease is often evident, and patients may run a low-grade fever. Acute kidney failure is common, in which the patient both stops filtering waste products from the blood and stops producing urine. These patients quickly become uremic, poisoned by the metabolic byproducts that are not being removed from the body. If treatment is instituted early many of them can be saved with aggressive fluid and diuretic therapy plus antibiotic treatment.
Diagnosis is further complicated by the necessity of multiple, time-consuming tests needed for an accurate picture of the infection.
Some percentage of leptospirosis victims are asymptomatic carriers, meaning that they hold the organism in the body (stored in the kidneys) and contaminate everything they urinate on, while not being made ill. These are the most dangerous lepto patients because they expose the greatest number of people and pets to sharing the disease.
Epidemiologists recommend that, unless your dog is at risk for severe reaction to the vaccine, or other contraindications are present, all dogs be vaccinated annually. Bacterins, vaccines against bacteria, do not confer immunity as long as vaccines against viral diseases. It’s the best way to keep both pets and people healthy.
See you tomorrow, Dr. Randolph.