[inlne:1]Warm weather means dogs get to spend more time outdoors, and most love to swim and explore their environment. It also means that local wildlife like raccoons and skunks are out and about. As harmless as most of these critters are, they often carry organisms infectious to other animals and humans. Recently, an organism has re-emerged that causes the disease known as Leptospirosis.
The bacterium Leptospira comes in assorted varieties, known as serovars. Each serovar preferentially infects a selected mammalian species to use as its carrier. When a host species animal is infected, the disease is usually mild and may go unnoticed. The animal can live unaffected symptomatically by this bacterium while continuously shedding the organism. If the same serovar goes on to infect an animal that is not a host species (like a dog), the results can range from undetectable to severe. Several serovars known to cause disease in dogs are most commonly found in raccoons, skunks, moles, mice, cattle and pigs.
Since the bacterium survives best in warm, moist weather, Leptospirosis is typically diagnosed in the spring and autumn. The organism is shed in the urine of infected animals and can survive up to six weeks. Dogs may become infected from contaminated water; wet grass, soil or food. Infection requires ingestion of the bacterium or contact with the gums or nose. It has been reported that infection is highest in large-breed dogs. This is likely related to the amount of time the dog spends outdoors, especially swimming. Infection can occur in rural areas but more reports are in suburban locations.
Most infected dogs show no obvious symptoms. These go unnoticed and the dog may exhibit nothing more than flu-like symptoms. However, more serious infections can develop where intravenous fluids and a long course of antibiotics is required. The antibiotics used are quite effective if a dog is treated early. However, symptoms may not appear for several weeks, and diagnosis may require several blood tests for confirmation.
The organism causes damage to blood vessels, especially in the kidneys and liver where failure and/or severe disease can occur. The dog may show non-specific signs like vomiting, dehydration, fever, loss of appetite or sudden collapse. Mucous membranes may develop a yellow tinge, indicating liver disease. Water intake may suddenly increase causing frequent urination. A lengthy hospital stay may be necessary until the dog is able to maintain hydration on its own. Organ failure and even death can result if untreated. In general, the earlier the diagnosis and treatment, the better the prognosis.
Finally, although rare, Leptospirosis can infect humans through an infected dog shedding the organism or through the environment. Typically, veterinarians and wildlife rehabilitators are most likely to be contaminated. Human cases are usually mild and may go unnoticed. Rarely, severe symptoms such as fever/chills, severe headache, vomiting, muscle and/or abdominal pain may occur. If left untreated, meningitis, kidney failure and liver disease are possible. The most effective way to prevent transmission to humans is with protective clothing, frequent hand washing and disinfecting possibly contaminated surfaces. Since infection with Leptospira can be so devastating, vaccination of dogs at risk is advised. A widely used vaccine for the most important Leptospira serovars has been reported to be quite effective. Rodent and wildlife control is important to keep the risk of infection low. It is difficult to keep larger dogs from swimming, but removing standing water and keeping dogs’ water and food bowls inside can help lower your dog’s risk of infection, and let you know that you are doing all you can to prevent Leptospirosis.
VCA Highlands Animal Hospital, 3451 Elkhorn Blvd., North Highlands, CA 95660