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Lyme Disease in Dogs

Reviewed by Dr. Celeste Clements, DVM, DACVIM on Friday, May 1, 2015
Posted October 24, 2011 in Dog Diseases & Conditions A-Z

Lyme disease is caused by a spiral-shaped microscopic organism, or spirochete, called Borrelia burgdorferi. This bacterium lives in the gut of the eastern black-legged tick, previously referred to as the deer tick (Ixodes scapularis) and the Western black-legged tick (Ixodes pacificus), and can be transmitted when an infected tick feeds on a dog, person, or other mammal. These ticks are extremely small, ranging from the size of a grain of sand to the size of a sesame seed. Black-legged ticks prefer to hide in shady, moist ground litter, but they can be found above ground, clinging to tall grass, brush, shrubs, and low tree branches. They also inhabit gardens and lawns, particularly at the edges of woodlands and around old stone walls, where deer and white-footed mice, the ticks' preferred hosts, thrive.

Lyme disease has been found in every state in the U.S. and some provinces in Canada, because pets and animals travel. It is however regionally important where the tick vectors live:

  • Northeast and mid-Atlantic, from northeastern Virginia to Maine;
  • North central states, mostly in Wisconsin and Minnesota;
  • West Coast, particularly northern California

Dogs are significantlymore likely to be exposed to B. burgdorferi from the bite of an infected tick than are people, but are less likely to become sick with Lyme disease.1 2

Lyme can affect dogs of all ages, breeds, and sizes. The more time a dog spends outside in areas where ticks are prevalent, the greater the risk! In addition to Lyme disease, dogs are at risk for many other different tick-borne infections. To learn more about other tick-borne diseases, visit

Dog in GrassThere are several scary things about Lyme disease:

  • People can also be infected by the same ticks that infect our dogs. If your dog is a tick magnet, make sure you talk to your veterinarian about proper protection. 
  • Ticks are not always easy to spot, and it is almost impossible to identify a tick bite—especially if your dog has a thick coat. 
  • Symptoms of Lyme disease vary and can be difficult to detect, with warning signs that may not appear until several months after infection.

Lyme disease can affect different organs and systems within the body. The most common symptoms you might spot are:

  • Recurrent painful joints that lasts 3–4 days, sometimes accompanied by loss of appetite and depression
  • Reluctance to move, or a
Related symptoms: 

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