If you and your pets spend a lot of time outdoors, especially in late summer and early fall, it is important that you know about a disease that peaks around this time: leptospirosis.

Leptospirosis is the name of the disease caused by spiral-shaped bacteria in the genus Leptospira. These bacteria prefer warm, moist environments are most often found in stagnant or slow moving water. Lakes, slow streams and even large, persistent puddles can harbor this spiral menace, and they are viable for months in these moist environments.


Leptospirosis tends to be peak after heavy rainfalls or floods. The organism is shed in urine, so any wet environment that has been contaminated by an infected animal’s urine is fair game for the transmission of disease.

Dogs (and very, very, very rarely cats) pick up the bacteria when they come into contact with infected urine. The bacteria can penetrate mucous membranes and wounds, so even bedding can become a potential source of transmission if it has been contaminated with infected urine.

Once the bacterial organisms enter the bloodstream, they replicate quickly. They first attack vessel walls and then move on to major organs, including the kidney, liver, central nervous system, spleen and eyes. Clinical signs become evident about a week after exposure.


Symptoms will vary depending on the severity of the disease. Pets with what is called peracute disease are overwhelmed with bacterial organisms and will die before showing signs. Luckily this is rare. Pets with acute disease will show symptoms related to blood vessel involvement: bloody nasal discharge, blood in the stool and small pinpoint bruises on the skin. Fever, vomiting, diarrhea and muscle aches are common in acute disease, too.

Most patients present with subacute disease. This phase of leptospirosis includes all of the clinical signs mentioned above plus major organ involvement. Most dogs who present with leptospirosis are already in kidney failure, so a significantly decreased appetite is to be expected, as well as dehydration. Jaundice may be seen if there is liver involvement, and central nervous signs will show if the organism has struck there, too.

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Treatment and Prevention

Fortunately, leptospirosis is very responsive to antibiotics. Affected patients may be hospitalized for supportive treatment, but can eventually go home with either penicillin or doxycyline to be given orally. The prognosis for recovery is good‚ÄĒabout 80-90% of patients recover.

A word of caution: leptospirosis is a zoonotic disease, meaning that it can also infect humans. You and your family are susceptible to infection from the same environments that cause illness to your pets, and if your pet has been diagnosed with leptospirosis, his urine will be infective to you, too, so it is crucial to take proper precautions.

There is a vaccine against four serovars of the genus Leptospira. This vaccine is recommended to pets at risk for contracting leptospirosis. If you and your pets think that hanging by the lake on a beautiful fall day is the picture of heaven, talk to your vet about including the vaccine against leptospirosis in your pet’s vaccine regimen today.

Nov 5, 2014
Pet Health

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