What is Lyme disease? How does my dog get infected?
Lyme disease is an infectious disease caused by bacteria called Borrelia. The bacteria are most commonly carried by the deer tick (also known as the black-legged tick). The tick becomes infected when they feed on infected mice, birds or deer. Dogs generally become infected after a tick has been attached for 1-2 days.
Where is Lyme disease found?
In the United States, Lyme disease has been reported in every state, but over 95% of cases are from the Northeastern, Mid-Atlantic, and upper Midwestern states, with a small number of cases reported along the West Coast, especially Northern California. In Canada, Lyme-positive dogs are found mostly from Manitoba eastward through to the Maritime provinces.
Can infection be spread directly from one dog to another dog or from my dog to my family?
Direct spread of Lyme disease from one dog to another dog has not been reported, even when infected and uninfected dogs have lived together for long periods. Spread of Lyme disease from dogs to people has not been reported either, but people are equally at risk for Lyme disease if they are bitten by an infected tick.
How is Lyme disease diagnosed?
There are several common tests used to screen for Lyme disease (SNAP 4DX PLUS™ or Accuplex ™4). These tests can detect antibodies of Borrelia exposure as early as three to five weeks after a dog has been bitten by an infected tick (even before the dog shows signs of illness). These antibody tests are often offered as part of a special test kit that looks for other tick-borne diseases. The test can be done by your veterinarian in-clinic or the blood sample can be sent to an outside laboratory for testing.
"If your dog is positive on one of the screening tests, your veterinarian may recommend repeating with a different test."
If the screening is positive, what is the next step?
If your dog is positive on one of the screening tests, your veterinarian may recommend repeating with a different test. Your veterinarian may also want to take samples of blood and urine to assess kidney function and to look for protein in the urine. A positive test for protein in the urine could signal serious underlying kidney disease; a complication of Borrelia infection.
If my dog tests positive, does he need to be treated?
The decision to treat Lyme disease is somewhat controversial since many infected or exposed dogs show no signs of illness. Remember a positive test only means that a dog has been exposed to Lyme disease, not that they are infected.
Factors that would support treatment include:
- signs of illness compatible with Lyme disease at the time of testing
- the presence of abnormal levels of protein in the urine.
How effective is treatment?
Antibiotic treatment (doxycycline) may be used as an additional diagnostic test; dogs experiencing joint pain will often significantly improve within one to three days. Unfortunately, this response to treatment isn’t 100% accurate as Lyme disease will naturally wax and wane with time. If your pet is not responding to treatment, or clinical signs recur during treatment, they likely have another disease. Additional diagnostic testing and alternate treatment would be required.
Often the obvious signs of Lyme disease resolve completely with antibiotics; however, it is unknown whether the bacterial infection is completely killed off in every patient or how to look for ongoing infection. Further research is needed to answer this question.