Dog owners look forward to this time of year, happily transitioning from the cold, unfriendly Midwestern winter and the confines of their home to the verdant fields of spring. But with the return of flowers and wildlife come warm-weather diseases, and one is particularly pernicious: leptospirosis.
Leptospirosis (a.k.a. lepto) is a bacterial infection transmitted by a wide variety of livestock and wildlife, including deer, opossums, squirrels, skunks, coyotes, raccoons, and rodents. The bacteria from infected animals are transmitted through urine (and other body fluids, except saliva) into water and soil, where they can survive for months. The organisms enter the body through the skin, eyes, nose, or mouth. Drinking, swimming in, and even walking through contaminated water can cause infection. Affected animals may excrete the bacteria into the environment for months and sometimes even years.
Because water and moist soil are sources of lepto, there’s a seasonality to the disease. Cases start appearing in the spring, with the highest number seen from July through November. The number of cases surges during periods of heavy rainfall.
Burgeoning suburbs have expanded into rural areas, forcing the wildlife to adapt to living among us. But if you assume that only rural or suburban dogs are at risk, think again. Besides a bumper crop of rats and mice, large populations of coyotes that have made cities like Chicago their habitat. Happily, you don’t have to worry about outdoor cats being infected; they seem to be unaffected by the disease.
Symptoms of lepto begin to appear 5 to 15 days after exposure and can be attributed to damage to the kidneys, liver, and vascular system. Fever, lethargy, vomiting, diarrhea, loss of appetite, and jaundice are commonly seen. The severity of clinical signs depends on how virulent the organism is; I’ve seen moderately sick dogs as well as dogs that are critically ill.
Blood tests can point us to lepto, but the diagnosis is only tentative: Other diseases produce similar symptoms and lab results. There’s a more specific test, the PCR, but the results can take 10 days — very frustrating! If we suspect that a patient has lepto, we’ll begin treatment without waiting for the PCR results. That is wise because it’s possible (although not very common) that the pet’s owners could contract the disease from their dog’s infected urine.
Leptospirosis is treated using long-term antibiotics. Some cases can be so severe that supportive care and hospitalization at a critical-care facility are needed to save the patient’s life. Dogs not given adequate treatment can die. Although many pets fully recover, a few can develop chronic kidney or liver disease, neither of which is curable.
A decade ago, the vaccines for lepto had serious adverse effects and earned a bad reputation that persists today. But the new vaccines are much better, and, as with other vaccines, serious reactions are very rare. The vaccine prevents the four main strains, or “serovars,” of lepto. Occasionally a vaccinated dog will contract the disease if he has the misfortune to be exposed to a less common serovar.
“But wait!” you say. “My dog hardly goes outside and barely steps on the grass! She doesn’t need this vaccination.” I learned otherwise from Max, a 6-pound Yorkshire terrier. I discussed risk factors with his owner, and she decided that his danger of exposure was quite low; the little guy hates getting his paws wet. Guess who got lepto? After a week at Veterinary Specialty Center in Buffalo Grove and $8,000 in medical expenses, Max recovered. But I’ve never forgotten it, and with the increasing incidence of lepto in Lake County, we’re recommending that all dogs get the lepto vaccinations: two injections three to four weeks apart, and an annual booster.
Yup, we know it’s yet another expense. But in this case, an ounce of prevention really is worth a pound of cure ̶ especially if the “pound of cure” runs into thousands of dollars.