Lyme disease is a clinical disorder caused by a microscopic organism, the spirochete, Borrelia burgdorferi, and is spread by ticks. The bacteria normally feed on small mammals, especially mice. Ticks then feed on the mammals and carry the bacteria to their victims. The deer tick is the most common tick involved in spreading the disease, although other ticks can pass it along, too. Ticks capable of spreading Lyme disease are most commonly found in the eastern United States, the upper Midwest and the Pacific Northwest. Lyme disease can affect different organs and body systems. The disease is named because of the initial discovery in human beings that occurred in 1975 in Lyme, Connecticut.
Lyme disease is most common in dogs but has been reported in other species. There appears to be no breed or sex predisposition. Outside, hunting and working dogs are more likely to be exposed to ticks than dogs kept indoors. Puppies appear to have a higher risk, and it is thought that less than five percent of dogs exposed to Lyme disease in an endemic (prone) area may develop clinical signs.
Human data from the Centers of Disease Control suggests that 85 percent of cases are from Eastern coastal states, 10 percent from the Midwest, 4 percent from the western states and 4 percent from the remaining states. The same figures may be true for dogs.

What to Watch For

The most consistent clinical sign in dogs includes lameness with swollen joints that are warm to the touch. Other symptoms may include heart, nervous system and kidney disease. Many dogs show no symptoms at all. Other signs include:
Recurrent lameness in a joint with complete recovery
Reluctance to move (pain)
Swelling in one or more joints
Anorexia
Fever
Lethargy
Depression


Diagnosis
Lyme disease is usually diagnosed by the presence of clinical symptoms and by blood tests. Diagnostic tests are also needed to exclude other diseases. After obtaining a history and performing a physical examination, your veterinarian may recommend the following diagnostic tests:
Blood tests for check for titers to Lyme disease (IFA or ELISA) may help to determine disease. This test detects the presence of antibodies against the bacteria. However, the test indicates exposure to the disease and does not always indicate infection.
Western blot test
Joint fluid analysis may be needed to exclude other causes of joint inflammation

Treatment
In the early stages of the disease, treatment with antibiotics is usually successful. Treatment will probably include:
Antibiotic therapy. This usually provides complete clinical recovery in 24 to 48 hours although antibiotics should be continued for 14 to 21 days (recommendations vary from 2 to 4 weeks). Antibiotics recommended may include tetracycline, doxycycline, minocycline, cephalexin, amoxicillin or ampicillin.
It is recommended that healthy asymptomatic dogs be treated and not those who test positive for serology. Without associated illness, a positive serologic tests can indicate exposure to Lyme disease and not infection.