Lyme disease is a clinical disorder caused by a microscopic organism (the spirochete, Borrelia burgdorferi). The disease is spread by ticks. Lyme disease can affect different organs and body systems. The disease is named because of the initial discovery, in human beings, that occurred in Lyme, Connecticut, USA.

The most common clinical signs in dogs include acute (and sometimes recurrent) arthritis (joint inflammation) and lameness (weakness). Other symptoms may include cardiac (heart), neurologic (nervous system) and renal (kidney) disease.

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 of Lyme disease. It is thought that less than 5% 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% of cases are from Eastern coastal states, 10% from the Midwest, 4% for the West states and 4% from the remaining states. The same figures may be true for dogs.

Watch for: The most common symptoms of Lyme disease is recurrent lameness in a joint with complete recovery, reluctance to move (pain), swelling in one or more joints, anorexia, fever and lethargy or depression. See your veterinarian if you observe these signs.