Lyme Disease in Dogs


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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.

For more information about the relative risk of Lyme disease in the United States, see the risk map at:

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


    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 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


    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.
  • Treatment of Lyme disease must be individualized based on the severity of the condition. Dogs with clinical signs and a positive high titer should be treated with antibiotics. Treating serology-positive asymptomatic dogs is not recommended.

  • Other medical problems can lead to symptoms similar to those encountered in Lyme disease. It is important to exclude these conditions before establishing a definite diagnosis.

  • Bacterial endocarditis causing septic arthritis caused by the presence of microorganisms or toxins in the blood or tissue, or immune-mediated arthritis

  • Chronic hemarthrosis, or blood in the joints, due to coagulation defects, either congenital or acquired

  • Crystal-induced arthritis (gout, pseudogout)

  • Degenerative joint disease

  • Drug reaction (sulfadiazine reaction in Doberman pinschers)

  • Ehrlichiosis. This disease caused by parasite infection can be diagnosed with Ehrlichia serology and platelet counts.

  • Immune mediated polyarthritis

  • Musculoskeletal injury or trauma

  • Osteochondritis dissecans (OCD) – inflammation of the bone and cartilage

  • Osteopathy (any bone disease)

  • Panosteitis (inflammation of every part of a bone)

  • Rheumatoid arthritis

  • Rocky Mountain spotted fever

  • Septic arthritis

  • Systemic lupus erythematosus

  • Diagnosis In-depth

    Certain diagnostic tests must be performed to confirm the diagnosis of Lyme disease and exclude other diseases that may cause similar symptoms. The following diagnostic tests are often recommended:

  • A complete medical history and physical examination should be obtained by your veterinarian. Special attention should be paid to joints, lameness evaluation and auscultation (stethoscope examination) of the heart.

  • Diagnosis is based on physical examination, history, clinical signs, rule-outs, positive serology and response to antibiotics.

  • Blood tests called IFA or ELISA may help to determine disease. The ELISA can detect antibodies to Lyme disease in dogs that have not been vaccinated for Lyme disease. A single positive titer can be an incidental finding in an endemic area and does not indicate disease. Most veterinarians consider a fourfold rise in antibody titer diagnostic of disease.

  • Western blot is useful to distinguish between antibody levels generated due to infection vs. those due to vaccination.

  • Joint fluid analysis may be done in arthritic or lame joints. This test can also help determine the cause of the lameness and rule out other infections.

  • Radiographs (X-rays) may be performed on swollen or lame joints. Swelling in the joint (effusion) is a common finding with Lyme disease but the radiography should otherwise should be normal.

    Your veterinarian may recommend additional diagnostic tests to exclude or diagnose other conditions or to better understand the impact of Lyme disease on your pet. These tests ensure optimal medical care and are selected on a case-by-case basis. Tests may include:

  • A complete blood count (CBC) may be needed to evaluate your dog for other problems such as infections, inflammations or platelet related diseases.

  • Serum biochemistry tests are usually normal although some muscle enzymes can be elevated during lameness.

  • Urinalysis may be recommended to evaluate the kidneys and bladder.

  • ANA or RF tests are done to evaluate for immune system changes that can cause similar clinical signs. These tests are usually negative with Lyme disease.

  • Ehrlichia titer may be completed. Ehrlichia is an infectious disease that can have signs similar to Lyme disease.

  • Coagulation (blood-clotting) profile may be completed to evaluate for bleeding abnormalities.

  • Blood cultures may be done to evaluate for signs of infection. This test is usually negative with Lyme disease.

    Treatment In-depth

    Treatment of Lyme disease must be individualized based on the severity of the condition and other factors that must be analyzed by your veterinarian. Treatments vary. If your dog has only a positive titer and no clinical signs, no treatment may be recommended. In this situation, regular follow-up visits to your veterinarian are important to ensure the condition does not progress. If the Lyme disease affects other organ systems such as the heart or kidneys, additional treatments are necessary and may include the following:

  • Antibiotics, which usually provide complete clinical recovery in 24 to 48 hours. This is thought to be due to a decrease in bacterial load, and not elimination of the bacteria because the antibodies stay persistent for long periods. Improvement is usually noted within three days of initiation of antibiotic therapy.

    Antibiotics for 14 to 21 days (recommendations vary from two to four weeks) such as tetracycline (often avoided in growing dog), doxycycline, minocycline, cephalexin, amoxicillin or ampicillin.

  • Steroid therapy. This should be avoided. Dogs that are serology positive and that have no symptoms are not generally treated.

    Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical and may include the following:

  • Administer any veterinarian prescribed medications. Observe your dog's general activity level, appetite and interest.

  • Schedule regular veterinary visits to monitor your pet's condition.

  • Blood samples should be checked to monitor the Lyme disease titer.

  • Of course, the precise follow-up depends on the severity of your dog's disease, response to therapy and your veterinarian's recommendations.

  • Be certain to contact your veterinarian if you are experiencing any problems treating your pet.

    If you live in an area at high risk for Lyme disease, discuss vaccination for Lyme disease with your veterinarian.

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    About The Author

    debra-primovic Dr. Debra Primovic

    Debra A. Primovic, BSN, DVM, Editor-in-Chief, is a graduate of the Ohio State University School of Nursing and the OSU College of Veterinary Medicine. Following her veterinary medical training, Dr. Primovic practiced in general small animal practices as well as veterinary emergency practices. She was staff veterinarian at the Animal Emergency Clinic of St. Louis, Missouri, one of the busiest emergency/critical care practices in the United States as well as MedVet Columbus, winner of the AAHA Hospital of the year in 2014. She also spends time in general practice at the Granville Veterinary Clinic. Dr. Primovic divides her time among veterinary emergency and general practice, editing, writing, and updating articles for, and editing and indexing for veterinary publications. She loves both dogs and cats but has had extraordinary cats in her life, all of which have died over the past couple years. Special cats in her life were Kali, Sammy, Pepper and Beanie.