Canine Lyme Disease

There’s an increase in ticks, and tick-related diseases, with the number of reported tickborne diseases more than doubling in the last 13 years.81

Disease Overview

Lyme disease is a bacterial infection transmitted by ticks to dogs, as well as to other animals and people.

Most Lyme disease in the United States is spread by the deer tick, which is found primarily in the Northeast, Southeast, and upper Midwest. The western black-legged tick is the primary cause of Lyme disease transmission in the western states (map pictured below).


  • Ticks that can transmit Lyme disease have expanded their geographic range and are now being found in places they weren’t seen 20 years ago82
  • Counties with high risk for Lyme increased 320% since the 1990s82
  • CAPC data shows Nationwide, dogs are being exposed to Lyme disease outside of traditionally endemic areas54
  • Approximately 75% of unvaccinated dogs in endemic areas will eventually test positive for Lyme disease55
  • The best way to protect dogs is year-round flea and tick control and vaccinating those dogs that visit or live in endemic areas56

U.S. Canine Lyme Disease Prevalence83


Lyme disease is transmitted to through the bite of a tick that is carrying the bacterial spirochete, Borrelia burgdorferi. When the tick bites the dog and takes a blood meal, the blood causes the borrelia to change its outer surface protein (Osp) from OpsA to OspC which allows it to move from the tick’s midgut into the dog’s blood stream. Once in the bloodstream, the Lyme disease organism is carried to many parts of the body and is likely to localize in joints.


  • Arthritis
  • Lameness
  • Fever
  • Anorexia
  • Fatigue


  • Lyme disease was traditionally thought to be limited primarily to the Northeastern region of the U.S. where deer populations were most dense. However, with the warming weather and thespread of the tick populations, Lyme disease is now prevalent in the majority of the U.S., increasing dogs at risk. Additionally,wgeography is no longer a rule out ith many people traveling with their dogs, for Lyme risk. Positive cases of canine Lyme disease have been reported across the U.S., with 39 states now reporting high and moderately high prevalence of canine Lyme disease.
  • Dogs at increased risk for Lyme disease include:
    • Active dogs that walk or hike in the woods
    • Dogs that play in fields
    • Dogs that spend time in the yard


  • Most commonly, dogs may present with fever, shifting leg lameness, swollen joints, enlarged lymph nodes, lethargy, depression and anorexia.
  • Less commonly, dogs will develop a protein losing nephropathy that can result in hypoalbuminemia, edema and eventually renal failure, which is known as Lyme nephritis.


  • Infection occurs 24-48 hours after attaching to a host. B. burgdorferiis is passed through the salivary glands of an infected tick into the animal.
  • Once the animal is infected with spirochetes from the tick, the spirochetes spread through connective tissue and may result in infections in the joints, heart, and neural tissue.78


Diagnosis is based on history, clinical signs, elimination of other diagnoses, laboratory data, epidemiologic considerations, and response to antibiotic therapy. Mixed infections should be considered when clinical signs are apparent.

Long incubation periods, persistence of antibodies for months to years, and the disassociation of the antibody response from the clinical stage of disease make diagnosis by blood testing alone impossible.

Merck Animal Health Vaccines


Two inactivated isolates of Borrelia burgdorferi initiate the production of borreliacidal antibodies against OspA and OspC to prevent Lyme infection

Professional Resources and Educational Materials

Keep your clinic and staff informed and aware of diseases and outbreaks.

Lyme Disease Pet Parent Guide


Share this printable brochure to educate pet parents about their dog’s risk for Canine Lyme Disease.


Absolutely Conserved – The Antibody Response That Counts


Learn how Nobivac® Lyme targets a conserved region of Borellia burgdorferi


Adjuvant This – Why Adjuvants Are Necessary


Learn why adjuvants are used to bolster the immune response


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54. Accessed July 26, 2018. 

55. Accessed July 26, 2018. 

56. AAHA Canine Vaccination Guidelines (Revised 2017). Accessed July 26, 2018. 

57. Centers for Disease Control and Prevention. Ticks: Geographic distribution. Available at: Accessed October 14, 2013. 

58. Goldstein RE. Borrelia burgdorferi, Lyme nephritis and total Lyme disease management. In: North American Veterinary Conference, eds. NAVC Proceedings 2006. Ithaca, NY: International Veterinary Information Service; 2006. Available at: Accessed February 25, 2013. 

59. Huston L. Canine Lyme disease nephritis: a rare fatal complication of Lyme disease in dogs. Available at: Accessed February 25, 2013. 

78. Companion Animal Parasite Council. Lyme Disease, Dog. Available at: Accessed March 29, 2019. 

81. Dogs continue to be at an elevated risk of heartworm disease and lyme disease in 2018. Accessed August 2, 2018. 

82. Accessed July 26, 2018. 

83. Companion Animal Parasite Council. Accessed September 29, 2018. 

84. Overview Of Lyme Borreliosis – Generalized Conditions Accessed August 3, 2019.

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