{"id":1082,"date":"2014-03-01T15:17:53","date_gmt":"2014-03-01T15:17:53","guid":{"rendered":"http:\/\/phosdev.com\/todaysveterinarypractice\/?p=1082"},"modified":"2022-02-16T18:52:17","modified_gmt":"2022-02-16T18:52:17","slug":"canine-lyme-disease-threat","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarypractice.com\/preventive-medicine\/canine-lyme-disease-threat\/","title":{"rendered":"Canine Lyme Disease: How Real is the Threat?"},"content":{"rendered":"

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Canine Lyme disease, also called canine Lyme borreliosis, is among the most familiar tick (Ixodes<\/em> species) transmitted infections known to occur in humans and dogs residing in North America.<\/p>\n

Despite being the subject of review articles,1,2<\/sup> research studies, scientific proceedings, and symposia, canine Lyme borreliosis continues to generate considerable controversy in clinical practice, particularly as it pertains to exposure risk, diagnosis, consequences of infection, and even prevention. This article addresses key controversies and current recommendations regarding management of dogs at risk for canine Lyme borreliosis.<\/p>\n

TRANSMISSION<\/h2>\n

Host & Reservoirs<\/h3>\n

The host-associated bacteria\u2014Borrelia burgdorferi<\/em>, a spirochete\u2014is maintained in a variety of wild animal reservoirs, ranging from rodents (principally the white-footed mouse), other small mammals (eg, chipmunks), and ground feeding birds (eg, American robin).<\/p>\n

Vector<\/h3>\n

The black-legged tick, or deer tick, which parasitizes the mammalian and avian hosts, unwittingly serves as a vector of B burgdorferi<\/em> to other mammals, including dogs and humans.<\/p>\n

Food Source<\/h3>\n

White-tailed deer\u2014often associated with Lyme disease\u2014are not reservoirs for B burgdorferi<\/em>. They are, instead, blood-feeding stations (and transport vehicles) for adult black-legged ticks. In recent years, increased deer tick populations are believed to be a result of similarly increased deer populations.<\/p>\n

PREVALENCE & DISTRIBUTION<\/h2>\n

Human Prevalence<\/h3>\n

In August 2013, preliminary results from 3 complementary studies conducted through the Centers for Disease Control and Prevention (CDC) suggested that approximately 300,000 people in the U.S. are diagnosed with Lyme disease, a significant increase from 2012 estimates of 30,000 reported cases. Of reported cases, 96% occurred in 13 states, particularly the northeastern U.S. and Upper Midwest; this distribution did not change from 2012 to 2013.3<\/sup><\/p>\n

Canine Prevalence<\/h3>\n

Canine Lyme borreliosis is not a reportable disease; therefore, precise estimates of disease prevalence are unavailable. However, compared with humans, dogs in endemic regions are at substantially greater risk for exposure to infected ticks. Surveillance reports of dogs with positive antibody test results suggest that up to 85% of dogs living in endemic areas are at risk for B burgdorferi<\/em> infection.<\/p>\n

Geographic Distribution<\/h3>\n

Today, risk extends beyond the traditional geographic boundaries defined\u2014the New England states, Wisconsin, and Minnesota, with a relatively high number of infected dogs reported annually in northern California, Oregon, and parts of Washington State (Figure<\/strong>).4<\/sup> Anecdotal reports from veterinarians practicing in western Pennsylvania, Ohio, Michigan, and central Illinois state that, over the past 5 years, risk for exposure to infected ticks is spreading.<\/p>\n

Results of surveillance studies in the U.S., Canada, and Europe designed to monitor the spread of infected ticks indicate that both climate change and migratory ground-feeding birds contribute to movement of infected ticks and increased risk for human and animal exposure.4-6<\/sup> These studies highlight the importance of continued surveillance\u2014through routine testing of dogs living in regions where the risk for exposure to Ixodes<\/em> species ticks is high.<\/p>\n

The concept of surveillance testing of healthy dogs for Lyme borreliosis, however, raises a series of important questions:<\/p>\n

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