Leptospirosis is a serious disease of mammals that is caused by a number of species of bacteria belonging to the genus Leptospira. In North America, this disease has begun to re-emerge as a threat to our companion animals in recent years, especially dogs. Cats can get this disease in very rare cases.
Many different strains or serovars of leptospira bacteria are found throughout the world. Each serovar is adapted to a different mammalian host, which it uses as a carrier or host species. When an animal belonging to the host species is infected, the disease is usually mild and may go unnoticed, although the animal may continuously shed the organisms into the environment. Infected animals shed the disease mainly in their urine. The disease is transmitted to other susceptible animals by direct contact with an infected animal or by exposure to water or soil contaminated by infected urine. If the susceptible animal belongs to a host species, the infection will usually be mild; if the same serovar infects an animal that is not a host species, the severity of the infection can range from mild to severe.
 The host species for the strains of leptospirosis that cause the most serious forms of disease in dogs include raccoons, skunks, voles, mice, cattle and pigs. Dogs typically become infected from drinking contaminated water, although the bacteria can enter the body across other membranes or through wounds or scratches on the skin. A high wildlife population in an area will increase the risk of exposure. Although the risk used to be higher in rural areas, as our cities continue to expand outwards, wildlife are being forced into inhabiting suburbs and more populated locations. In short, if your dog is a field or hunting dog or if you have skunks and raccoons visiting your yard, especially if your yard has poor drainage, then the disease should be a concern to you.
It usually takes 5-14 days for the disease to develop after exposure, but it can be as short as a few days or as long as a month. Antibodies begin to appear in the blood of an infected animal 7-10 days after infection, and the disease can be diagnosed by a test that detects these antibodies. Clinical signs of leptospirosis in dogs vary with the age and immune status of the animal, and the aggressiveness of the particular strain or serovar.
The majority of leptospirosis infections are subclinical, meaning that no obvious signs of illness are present. Unfortunately, we are seeing an increase in the number of serious infections in pet dogs. Dogs that have been infected with leptospira bacteria may suddenly develop a high fever, loss of appetite, lethargy, stiffness, severe muscle pain, vomiting, a painful abdomen, and/or bloody urine. The organism typically will invade the liver or kidneys, and without rapid and aggressive treatment it can leave to severe damage, even organ failure. Treatment includes antibiotics and hospitalization for intravenous fluid therapy.
Leptospira needs a neutral to alkaline soil with moist conditions and warm temperature (7-36oC or 44-95oF) in order to survive. Stagnant water, such as that found in swamps or areas of poor drainage, meets these requirements. Under ideal circumstances, the organism can survive in the environment for up to 6 weeks. As a result, most cases of leptospirosis are diagnosed between spring and fall.
You can help prevent transmission of this disease by keeping your pets away from swampy areas, improving the drainage of your property, and making your yard less attractive to wildlife. Open areas with more sunlight will decrease dampness after a rainfall, and may act as a discouragement for wildlife. To minimize water collection, install drainage tile in swampy areas or raise the ground level with landscaping. Do not leave your pet's food and water bowls outside where they can become contaminated by wildlife. You can greatly reduce the risk of exposure by not allowing your pet to run off leash in wooded, swampy areas between July and the first hard freeze of winter.
Your veterinarian can vaccinate your pet against two of the strains or serovars that are prevalent in dogs. The available vaccines are effective for about one year, and booster vaccines must be given annually. Unfortunately, the available vaccines do not provide protection against all of the serovars that can cause disease.
Finally, it should be noted that leptospirosis is zoonotic, or can be transmitted to humans. Therefore, it is important that you avoid contact with contaminated urine or stagnant waters. Although it is considered rare for a human to acquire this disease from an infected dog, it is prudent to thoroughly wash your hands after handling any animal.
If you have further questions, do not hesitate to discuss them with your veterinarian.
For more information about the disease in humans, consult the Centers for Disease Control website at http://www.cdc.gov/ncidod/dbmd/diseaseinfo/leptospirosis_g.htm
Caution: These news items, written by Lifelearn Inc., are licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written permission of Lifelearn Inc. Please note that the news information presented here is NOT a substitute for a proper consultation and/or clinical examination of your pet by our clinic veterinarian.
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