Lyme disease (or Lyme borreliosis) is caused by the Borrelia burgdorferi bacteria,1 and is transmitted via the bite of an infected black-legged tick.2 The disease takes its name from the town of Lyme, Connecticut; where an epidemic of arthritis occurred in the mid-1970’s.3


The Lyme vaccine is administered according to the following schedule:

Schedule Vaccine(s)
10 to 16 Weeks Initial Lyme Vaccination
Two (2) to Three (3) Weeks Later Lyme Vaccine Booster
Every Year Thereafter Lyme Vaccine Booster

Lyme vaccines are administered in series. It is important not to miss the booster of your dog’s first vaccine, as doing so may necessitate restarting the series.

The initial vaccine and booster must be administered two (2) to three (3) weeks apart; if not administered within six (6) weeks (42 days), the series must be restarted.

Dogs unvaccinated for a period of two (2) years or more must restart the series.

Testing for Lyme is required for dogs who are seven (7) weeks (49 days) or more overdue for their Lyme vaccine.


The primary vector for Lyme disease is the blacklegged tick.45 In the United States, three closely-related species of ticks of the genus Ixodes are associated with the disease: Ixodes scapularis in the northeastern, midwestern, and southern states; and I. pacificus and I. neotamae in the western states.4 While both I. scapularis and I. pacificus are known to feed on dogs and humans,4 the primary host for I. neotamae is the dusky-footed woodrat (Neotoma fuscipes).67

Blacklegged Tick Life Cycle

Blacklegged ticks, commonly called “deer ticks”, have a two-year life cycle. Eggs are oviposited in the spring, and larvae emerge approximately one month later. Larvae feed once in the summer, usually on birds and small mammals, at which stage they are most likely to become infected with the Borrelia burgdorferi bacteria.

Larvae then over-winter, and in the following spring molt into nymphs, which then feed in late spring or early summer.

In the fall, nymphs molt into adults, which usually feed on larger mammals (often the white-tailed deer), on whose bodies they mate. Females die after laying their eggs, whereby the two-year cycle begins again.

Infected nymphs feeding on mice or larger mammals such as deer, dogs, or humans; and adult ticks, whose higher rate of infectivity may be due to their longevity and repeated exposure to infected mammals and birds, are considered the most likely source of infection for dogs and humans. An infected tick usually must be attached for at least 48 hours before transmission of disease-causing bacteria (spirochetes) can occur.489

(Adapted from Greene CE, Straubinger RK, Levy SA. Borreliosis. In: Greene CE, ed. Infectious Diseases of the Dog and Cat 4th ed. St. Louis, MO: Elsevier; 2012: 450-452.4


Lyme disease can cause transitory fever, anorexia (lack of appetite), and arthritis (painful and swollen joints) and generalized weakness or lethargy.10111213 In severe cases, kidney damage has been known to occur.141516 In most cases, symptoms take between two and six months following infection to manifest.41718192021222324


Testing for Lyme, as part of our in-house Laboratory service, indicates the presence of antibody to the Borrelia burgdorferi bacteria. While a positive Lyme test result may not indicate clinical illness,18 due to the high percentage of dogs testing positive for the Borrelia burgdorferi bacteria who remain asymptomatic, Lyme and other tickborne diseases present with similar symptoms, most commonly fever, anorexia, central nervous system signs, and lameness, and arthritis. For this reason, testing is recommended in dogs exhibiting symptoms frequently associated with such diseases, to rule out the possibility of a different, secondary, or mutual infection (co-infection).

Because of these factors, the test we utilize, in addition to testing for Lyme borreliosis, also tests for tickborne diseases anaplasmosis (Anaplasma phagocytophilum) and ehrlichiosis (Ehrlichia canis), while at the same time testing for Heartworm Disease (Dirofilaria immitis).25 Notably, this test has not been known to cross-react with antibody response to a Lyme vaccine,26 itself part of a comprehensive Lyme-prevention protocol (See: Prevention).

Additionally, while a Lyme positive test result may not appear until four (4) to six (6) weeks following a bite by an infected tick;27 because symptoms may take up to two (2) to six (6) months (eight (8) to 24 weeks) to develop, if you are concerned about your dog’s health following a potential tick bite or a tick infestation please call to schedule an Appointment so your veterinarian may determine which protocol is most appropriate for your dog.


In humans, Lyme disease is the most commonly reported vector-borne disease in the United States.28 In particular, studies done by the Connecticut Department of Public Health have shown that of any state, Connecticut (from where Lyme disease gets its name)2 has the highest number of reported Lyme disease cases in humans relative to its population.29

Ticks are thought to be the chief source of vector-borne diseases among animals in North America,30 yet while dogs testing positive for the Borrelia burgdorferi bacteria have been reported in all 50 states,31 only five percent (5%) of dogs infected with the bacteria (seropositivity) develop symptoms (clinical illness).11 Therefore, differentiation between seropositivity and clinical illness (Lyme disease) is necessary in interpreting these data accurately. It has been suggested that the disparity between percentage of incidence of seropositivity and the development of clinical illness may be due to exposure to an infectious but nonpathogenic strain of Borrelia burgdorferi, or infection with low numbers of B. burgdorferi organisms in a host with an efficient immune system.32


Lyme disease, like other tickborne diseases, such as anaplasmosis33 and ehrlichiosis,34 is treated with tetracycline antibiotics, typically doxycycline.35 Therapeutic protocols generally last one month, at which point a dog’s condition is re-evaluated.


Maintaining annual Lyme vaccinations along with a year-round tick preventative, such as an oral, topical, or impregnated collar acaricide (a pesticide that targets members of the taxon Acari, of which mites and ticks are included36) is highly recommended,3738 as, while highly effective in blocking transmission of the Lyme disease-causing bacteria,39 Lyme vaccines do not prevent other canine-acquired tickborne diseases;40 which inclde anaplasmosis, ehrlichiosis, and Rocky Mountain spotted fever (Rickettsia rickettsii), among others.41 (See: Disease Transmission in Flea & Tick Prevention for a comprehensive list of tickborne diseases).

Being in an area where the Borrelia burgdorferi bacteria is endemic (potential for contact with infected ticks is high), such a prevention protocol is highly recommended, not only for preventing Lyme disease, but other tickborne diseases as well.

See Flea & Tick Prevention for more information regarding year-round tick preventatives.

Prevention Tips

(As suggested by the Centers for Disease Control and Prevention (CDC)42 & the Companion Animal Parasite Council43)

  • Check your pet(s) for ticks daily, especially after they have spent time outdoors.
  • If you find a tick on your pet, remove it right away. Ask us to show you the safest way to remove a tick without breaking off the head and leaving its mouthparts attached to your pet, as they can still transmit Lyme disease or cause a secondary infection.44
  • Ask us to conduct a tick check during your Annual Wellness Visit.
  • Ask us about the aforementioned tickborne diseases and their presence in our area.
  • Talk with your veterinarian about using a tick preventative on your pet.

Additional Resources

The Companion Animal Parasite Council, an independent council of veterinarians and other animal health care professionals creating guidelines for controlling internal and external parasites threatening the health of pets and people,45 presents information regarding Ticks on Dogs and Ticks on Cats, while IDEXX Laboratories, a provider of diagnostic and information technology solutions for animal health,46 also presents information regarding Dogs and Ticks.


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  2. ^ a b DHP: A Brief History of Lyme Disease in Connecticut State of Connecticut: Department of Public Health. Updated August 13, 2013.
  3. ^ Jaenson TGT. The epidemiology of Lyme borreliosis. Parasitol Today. 1991; 7: 39-45.
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  5. ^ Lyme disease transmission. Centers for Disease Control and Prevention. Updated March 4, 2015.
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  20. ^ Straubinger RK, Summers BA, Chang YF, Appel MJG. Persistence of Borrelia burgdorferi in experimentally infected dogs after antibiotic treatment. J Clin Microbiol. 1997; 35: 111-116.
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  25. ^ SNAP 4Dx Plus Test screens for more vector-borne diseases. IDEXX Laboratories.
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  40. ^ Merial Ltd. Borrelia Burgdorferi Bacterial Extract. 2009.
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  43. ^ Adapted from Ticks | Pets & Parasites: The Pet Owner’s Parasite Resource. Companion Animal Parasite Council.
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  46. ^ Our Purpose – IDEXX US. IDEXX Laboratories.