Recently, a local news channel has reported an increase in the number of cases of illness in dogs caused by Leptospirosis in Macomb County. Due to this, we have received many phone calls from our clients concerned about their pets catching this disease. Leptospirosis is a bacterial disease that is found in all parts of Michigan. It is also found in both rural and suburban environments in semitropical areas of the world with alkaline soil conditions. Clinical cases are more commonly diagnosed in the Summer and early Fall, and those numbers increase in years that have had heavy rainfall. In addition to infecting our pets, Leptospirosis is also a zoonotic disease. This means that it can be passed from an animal to a human and can cause disease in that person.

Lepto can be carried by rodents such as rats, mice, raccoons, skunks, opossums and voles. It can also be carried by cows, horses, pigs and dogs. Cats can be carriers which means they can be infected and shed the organism into the environment for variable periods of time after exposure, but generally do not become sick from the disease.

The Leptospira bacteria is transmitted from the urine of infected animals and also from water or ground that has been contaminated by infected urine. Leptospira can penetrate the lining of the nose, mouth and eyelid, and can also enter the body through scratches or open sores on the skin. Transmission also occurs through bite wounds, and by ingestions of contaminated tissues, soil, water, bedding, food and other inanimate objects. Humans become infected by these same routes.

Leptospira bacteria
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Once inside the body, the organisms replicate quickly in the bloodstream before moving into the tissus. In dogs, the liver and kidneys develop the highest levels of infection and serious damage can be done to these organs. Clinical signs typically appear in 7-10 days. Animals that are treated or develop appropriate immune responses usually survive. However, some of the bacteria can still survive resulting in long-term infection and ongoing shedding of organisms in the urine. These long- term infections can also lead to chronic active hepatitis or chronic renal disease. Some Lepto infections can be rapidly progressive and can be fatal.

The most common clinical signs of acute leptospirosis are depression, lethargy, vomiting, loss of appetite, fever, pale mucus membranes, muscle pain and increased heart rate. In subacutely infected dogs, the physical exam findings may be more vague and can include bleeding syndromes, liver disease, kidney disease or a combination of both liver and kidney disease. In dogs that develop chronic disease, increased thirst, increased urination, weight loss, ascites (fluid in the abdomen) and signs of liver failure are the most common manifestations of Leptospirosis.

Diagnostics should include a complete blood count (CBC), a biochemical profile and a urinalysis. These can show an increase in white blood cells, sometimes decreased platelets and/or red blood cells, elevations in the kidney and/or liver enzymes and abnormal electrolyte counts. If Lepto is suspected, additional testing is necessary to confirm the diagnosis.

There are multiple tests available. These include a DNA-PCR test which can be a rapid method of detecting the DNA of the Leptospira bacteria in a sample. This is usually performed on urine or blood. The test does have limitations. It needs to be done before the animal is started on antibiotics because the antibiotics can clear the bacteria from the urine very quickly. In animals that have been on antibiotics, sick for a long time, or mildly affected, there may not be enough bacteria present for the test to detect. In addition, urine shedding of the organism may be intermittent. All of this can result in a negative result. A negative DNA-PCR test does not rule out infection.

The most common and standard test for diagnosing Leptospirosis is the Microscopic Agglutination Test. This test is designed to detect antibodies against Leptospirosis in the dog's blood. This test is also referred to as a "Lepto Titer".

This test also has it's limitations. Positive titers can result from active infection, previous infection or vaccination. The titers can also be negative in early disease. This test may need to be run more than once to confirm the diagnosis. Typically if the titers are low or normal, the test will be rerun in 2 to 4 weeks to evaluate for increases in the values. Documentation of a negative titer becoming positive over time, a single titer greater than 1:3200, or a fourfold increase in antibody titers combined with appropriate clinical signs are suggestive of clinical Leptospirosis. Another drawback to this test is that it can take days or longer to get the results back.

Treatment is available and includes fluid therapy and antibiotics. There are two phases of treatment, the first treats the acute phase and the second treats the "carrier state" (the time when the animal is still shedding the organism through their urine but they are no longer showing clinical signs of illness). Unfortunately, in some cases despite appropriate therapy the disease may progress and become fatal.

Humans become infected by direct contact with urine or contaminated bedding, etc. Pet owners should avoid getting urine in their eyes, nose, mouth or skin if they suspect their pet has been exposed to Lepto. Wearing gloves and thorough disinfection of contaminated areas is recommended. Questions should be directed to your human physician.

There are multiple strains of Leptospirosis. Vaccination against Lepto is available and highly recommended. At Southpointe, we vaccinate against 4 strains of Lepto. Feel free to contact us with any additional questions you may have about this disease.