Lyme disease is caused by the
spirochete bacteria Borrelia burgdorferi. The spirochete is acquired through
the bite of an infected tick. Lyme disease is now regarded as the most common
tick-borne illness in the United States.
This disease was first recognized in 1975, following an outbreak of what
appeared to be acute arthritis in several rural
communities in southeastern Connecticut, including the town of Old Lyme.
Currently, most cases are found in wooded locations in the Northeast, upper
Midwest (including much of Wisconsin and Minnesota), northern California, and
the Pacific Northwest.
Encephalitis is an inflammation
of the brain. Symptoms include fever, depression, behavior and personality changes (especially
aggression), uncoordinated gait, seizures, stupor, and coma.
Canine distemper is the most common cause of encephalitis in dogs. Signs
develop two to three weeks after the onset of the disease. Other causes of
viral encephalitis include rabies, pseudorabies, and herpesvirus. Rabies is a very serious
disease, but with present-day vaccination programs the disease is...
The white-footed mouse is the principal reservoir for the spirochete. Birds
can also harbor it. The white-tailed deer supports the tick, but not the
spirochete. Lyme disease is spread primarily during tick season (May through
August), peaking in the month of July, but ticks can be active any time
the temperature is over 32°F (0°C).
The disease in dogs is most commonly
characterized by the sudden onset of lameness. In fact, lameness is often the
only sign of infection. One or more joints may become swollen and painful to
the touch. Some dogs run a fever and experience weakness, lethargy, loss of
appetite, and weight loss. The lameness may last only a few days, but in some
cases it becomes chronic and persists or recurs for months.
Kidney problems are the next most common sign. An acute cardiac syndrome is
quite rare. Both of these syndromes are usually fatal.
Most dogs exposed to Lyme disease do not become ill. Serological blood tests
will indicate whether a dog has been exposed to the disease. Dogs may not test
positive until a few weeks after exposure. New serologic tests can distinguish
between dogs with vaccine immunity and dogs with natural exposure. A rising
antibody titer in the absence of recent vaccination, however, indicates active
infection. Western Blot and ELISA blood tests are now both used to detect
exposure. Many dogs who test positive for Lyme disease will also have other
tick-borne diseases, such as ehrlichiosis and
WebMD Veterinary Reference from "Dog Owner's Home Veterinary Handbook"