Understanding Lyme Disease

If you feel confused about canine Lyme disease, you are certainly not alone. A frequent subject on the news, Lyme disease can be the cause of insidious symptoms in dogs (and in people; cats, however, are unlikely to be affected). Lyme disease is caused by a bacterial spirochete, Borrelia burgdorferi, which is transmitted by deer ticks of the Ixodes species. To complicate things further, the spirochete can be carried and transmitted by other ticks and even by deer flies, fleas and mosquitoes -- although the deer tick, Ixodes, is the most common carrier or vector. The tick itself becomes “infected” with the bug primarily by deer mice rather than by deer themselves. Once infected, the tick can then can then transfer Borrelia burgdorferi to any host it bites, including dogs. Lyme disease has become the most frequently diagnosed tick-borne disease in North America, a considerable threat to the health of humans and their canine companions.

Lyme disease is characterized by inflammation of many body systems, causing a variety of symptoms -- or clinical signs -- across joints, lymph nodes, the central nervous system, the heart and other tissues. The inflammation sparked by Borreliosis may lead to long-term disease including arthritis and heart or kidney failure. It can even be transmitted by pregnant dogs to their unborn offspring via the uterus. Such generalized disease may at first appear only as lameness and loss of appetite; the characteristic “bulls-eye lesion” or rash is rarely apparent in animals.

Just how worried should you be about Lyme disease? Because its clinical signs are nonspecific, a diagnosis may be overlooked until the disease has done some measurable and long-term damage. For this reason, it is particularly important to be aware of Lyme disease if you happen to live in a high-risk region. Areas of the United States in which Lyme disease is currently endemic (present in high numbers) include California and Oregon, the mid-Atlantic states and New England, and a midwestern band running down through Minnesota, Michigan and Missouri.

If you live in an endemic area (or if you are planning to travel with your pet), talk to your veterinarian about a vaccination for Lyme disease. Although vaccination does not provide complete protection against disease (few vaccines do), it may partially protect your dog and give you some peace of mind. Because many tick bites occur close to home, it may help to remove tall grass and brush around your home and yard. Avoid tick-infested areas especially during the months of late spring and early summer, and examine your dog (and yourself) frequently for signs of ticks. If you do find a tick, remove it immediately (ticks must be attached at least 24 hours to transfer the spirochete) and keep it in a jar for identification.

Fortunately, Lyme disease is relatively uncommon. Even if your dog is bitten by an infected deer tick, chances that the spirochete will be transmitted are small; fewer than 5 per cent of bitten animals go on to acquire active infection. Also fortunate is the fact that, particularly if caught early, Lyme disease can be successfully treated with antibiotics.