Using Dogs to Map Lyme Disease Risk

Dogs may help researchers map the geographic spread of Lyme disease. Because dogs are frequently exposed to ticks and are routinely tested by veterinarians, canine infection data can provide valuable insight into where Borrelia burgdorferi, the bacterium that causes Lyme disease, is circulating.

There is often a delay in diagnosing Lyme disease in dogs. Based on their review of the literature, the authors summarized several reasons for this delay:

1. “The first signs of clinical disease in dogs are non-specific, including fever, general malaise, lameness, and swelling of local lymph nodes. These symptoms are likely to be overlooked by dog owners because they are transient, lasting only a few days.”
2. “Detecting the later stages of disease requires recognition of pain; however, a standardized protocol for pain assessment in veterinary species is lacking and mainly relies on dog owners to report disease symptoms.”
3. “The assessment of pain in dogs can be difficult as they cannot self-report and is often reported by the owner as lethargy, decreased activity, or difficulty getting up, walking, or navigating stairs.”
4. “It is often not until the dogs exhibit the characteristic shifting leg lameness several months after infection that owners note abnormalities.” [1]

Researchers mapped Lyme disease across the United States using 11,937,925 Borrelia burgdorferi serologic test results from dogs collected within the 48 contiguous states between 2011 and 2015, according to a study published in PLoS One. [1]

Watson, from Clemson University, reported that 759,103 of those dogs tested positive for Lyme disease.

Seropositivity against B. burgdorferi was established using the late-phase C6 antigen ELISA rather than the two-tier surveillance case definition established by the Centers for Disease Control and Prevention (CDC).

The study confirmed a high prevalence of B. burgdorferi antibodies in dogs in the 14 states identified as endemic for Lyme disease and high-risk for humans:

Connecticut, Delaware, Maine, Massachusetts, Maryland, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Wisconsin.

“Perhaps most striking is the recognized expansion of seropositive dogs on the northern border of the contiguous U.S. along the Canadian border…”

The authors also noted higher prevalence of B. burgdorferi antibodies in dogs from additional states.

“We observed an expansion of this endemic range to include Northern California, Southeastern Oregon, Southwestern Idaho, Eastern Colorado and Northern New Mexico,” writes Watson. [1]

[bctt tweet=”An increasing number of dogs are testing positive for Lyme disease in expanded geographic regions.” username=”DrDanielCameron”]

“Perhaps most striking is the recognized expansion of seropositive dogs on the northern border of the contiguous U.S. along the Canadian border, including North Dakota and the border of Northern Montana and Idaho.”

The growing number of dogs testing positive for Lyme disease across expanding geographic regions raises concerns about public health.

“The westward expansion of canine Borrelia burgdorferi seroprevalence from Minnesota into North Dakota mirrors recent reports that Lyme disease is poised to become a significant human public health concern in North Dakota,” Watson notes. [1]

The authors also observed a convergence of infection patterns in the Great Lakes region.

“Of note is the apparent convergence of Borrelia burgdorferi infection of dogs from the Northeastern and Mid-Central United States in the Great Lakes region, encompassing Indiana, Ohio, Illinois, Kentucky and Michigan.”

The findings suggest that annual testing of dogs in these regions may help track the spread of Lyme disease.

“Annual testing of dogs in these states, as well as North Dakota and bordering Canadian provinces, is strongly warranted,” the authors conclude.

Other regions may also benefit from routine surveillance. For example, in 2015, 606 of 57,785 test results reported in South Carolina were positive for B. burgdorferi.

Monitoring Borrelia burgdorferi antibodies in dogs may therefore serve as an early warning system for both veterinary and human Lyme disease risk.

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention