Lyme Disease

District Vet – April 2017

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Be prepared for an invasion. Not from across the ocean, but from little critters hitching a ride on mice: ticks. Each year the territory of ticks carrying Lyme disease appears to be spreading, and urban and suburban environments are ripe for the reason they spread: mice. While traditionally people have blamed Lyme disease on deer, mice appear to play an even larger role in spreading disease-infected ticks.

Research by ecologists has shown that the numbers of mice the previous year correlates with the number of Lyme cases the following summer. Due to mild winters during the past decade, the population of mice has increased, and the range and severity of Lyme disease has increased as well.

The Centers for Disease Control (CDC) tracks Lyme cases, and the spread of Lyme has been startling. Lyme was originally confined to New England and some areas of Wisconsin. It now can be found from Maine through Virginia, across Wisconsin and Minnesota, and in smaller pockets throughout the country. Ecologists suspect this is due to larger populations of deer, more fragmented forests (mice thrive in small patches of woodlands), decreased predators feeding upon mice and deer, and increased travel by people. DC has plenty of mice and great mouse habitat like small gardens and small patches of woodlands.

Lyme is spread via an infected tick biting either you or your dog (it is possible in cats but less frequent). Infected ticks carry the organism Borellia burdorferi in their saliva and inject it into the animal while feeding. In general it takes over 24 hours for the tick to transfer Lyme to its host once it attaches. The disease is treatable in both humans and dogs, but prevention is key.

Always check yourself and your dog after playing outside. Simple walks in the neighborhood are sufficient to have ticks jump onto you and the pup. Look in places for a tick to hide: behind the ears, in the groin area, under the arms. If you spot a tick on yourself or your pup, remove it as soon as possible. Grasp it with tweezers as close to the skin as possible and pull it off. Do not squeeze its body.

For dogs, we have a threefold method of prevention: removal of ticks, oral and topical tick preventives, and vaccination. The most effective preventives focus on killing ticks as soon as possible. Simparica, NexGard, and Bravecto work by causing uncontrolled neurologic issues in ticks, and the ticks rapidly die. The medications have a very high affinity for a specific chemical in ticks (and fleas) and usually cause no ill effects in dogs.

When giving any of these three preventives, monitor your pup for adverse reactions such as vomiting, tremors, or simply not feeling well. Side effects are quite rare and pass with time. The risk from Lyme and other tick-borne disease is much greater than the risks from the preventives.

There are several Lyme vaccinations available as well. They prime the immune system to recognize the Borellia organism and mount an immune response, thus decreasing the likelihood of clinical disease. Here in DC the vaccine is recommended for most dogs.

Even with preventives and vaccination, Lyme can still be transmitted. We recommend that your dog be tested for Lyme once per year as part of annual parasite testing. If positive for Lyme, treatment can help prevent problems from arising.

Tick and parasite control is complicated and requires several different paradigms. We veterinarians are here to help keep your pup (and to a degree you) safe from ticks and tick-borne diseases. As always, please let us know how we can help.

Dan Teich, DVM, is at District Veterinary Hospital, 3748 10th St. NE, Washington, DC 20017; 202-827-1230 and desk@districtvet.com.