OVERVIEW and DISEASE TRANSMISSIONLyme disease is one of the most commonly diagnosed infections in dogs in our area. Our practice diagnoses several dogs with Lyme disease every day. Lyme disease is the result of infection by a spirochete (bacteria-like organism), Borrelia burgdorferi, that is transmitted through the bite of an infected tick. Ticks bite in order to feed on blood. Although Lyme disease was named for the Connecticut town of Lyme in 1975, the disease itself has been around for at least 100 years. Most cases in the United States occur in the northeast, but Lyme has been reported in all 50 states. In our area, Lyme is transmitted by the deer tick, Ixodes scapularis. An adult deer tick lays approximately 2000 eggs in the spring. These eggs hatch into tiny larvae, so small that they feed primarily on small prey such as the white-footed mouse. If the mouse is infected with Borrelia, the Lyme spirochete, the tick larva becomes infected at this stage. After feeding on the mouse, the larva drops off and lies dormant until the next spring when it molts into a nymph. The nymph is a bit bigger (about the size of a poppy seed - still very difficult to spot!) and therefore can reach bigger prey, such as a deer, dog, or human. Nymphs are the most common transmitters of Borrelia. When the nymph has had its fill of blood it drops off the animal, again becomes dormant for a few months, and then molts into an adult in the fall. The adult tick will also seek prey from which to take a blood meal. Infection with Borrelia can occur during any feeding if the larva, nymph, or adult takes a blood meal from an animal that is infected. Once the tick is infected with Borrelia, it can pass the infection along to any animal on which it feeds, however, a tick usually needs to be attached and feeding for at least 24 hours before it can transmit the Borrelia organism. It is important to note that Lyme disease is not transmitted from mammal to mammal - rather, it must be passed through the bite of a tick. SIGNS OF INFECTIONSigns of infection in dogs vary significantly from those seen in humans. Eighty percent of humans will develop a bulls-eye rash and flu-like symptoms after being bitten by an infected tick. This can then progress to joint pain, neurologic issues, or other symptoms within a few weeks. Dogs rarely experience this progression of events. In fact, dogs can be infected for weeks to months before any signs of infection become apparent, if signs become apparent at all. In dogs, the most common signs of Lyme disease are lethargy, poor appetite, lameness or joint pain (often inconsistent), and sometimes fever. Rarely, Lyme disease in dogs may lead to heart problems, neurological problems, or kidney dysfunction or failure. Although cats can get other tick-borne illnesses, they do not appear to be affected by Lyme disease. TESTINGThe quickest way to test for Lyme disease is through the use of our in-house 4Dx test. This test detects heartworm, Lyme disease, ehrlichia, and anaplasmosis. Heartworm is transmitted by mosquitoes (see our Heartworm page here), while the other three diseases are transmitted by ticks. This test is run annually during your dog's physical examination or if there is suspicion of infection. The 4Dx test is an antibody test, which means that it detects your dog's immune response to the Borrelia organism. A positive test means that your dog has been exposed to the Borrelia (bitten by an infected tick and invaded by the organisms) within the past few years. It does not necessarily mean that there is still Borrelia infection in your dog's body. Another test, the C6 Quantitative Test, may be sent out to the laboratory to help confirm current infection if there is any question. TREATMENTFortunately, Lyme disease is more successfully treatable in dogs than in humans. Most dogs will be prescribed Doxycycline, an antibiotic, for one month. Although an infection relapse is possible, this treatment is effective in the majority of cases. Dogs who are already showing significant illness may require hospitalization and more aggressive treatment. PREVENTIONThere are two ways to prevent Lyme disease - vaccination and tick prevention. No method works 100% of the time, so it is best to combine both types of prevention for the best protection. The canine vaccinations available have been subjected to years of testing for safety and efficacy. Vaccination is recommended for most dogs, but each pet's age, health, and lifestyle will be evaluated individually by your veterinarian prior to receiving a vaccine recommendation. The first time your dog receives the Lyme vaccination he will need a booster in 3 to 4 weeks. After this initial series of 2 vaccines, annual re-vaccination is recommended. Tick prevention is accomplished through the use of monthly topical products such as Advantix and Frontline Plus or neck bands such as Scalibor and Preventic. There are also products available for treatment of your yard against ticks. Year-round prevention is recommended in this area, as ticks will feed if the ambient temperature is above freezing. Your veterinarian will recommend the best prevention for your pet after a thorough evaluation and discussion with you. TICK REMOVALTicks are most commonly found in grassy or brushy areas or those covered with leaf litter. It is important to check your dog for ticks and remove those you find with a tick removal tool or tweezers. But remember, the nymphs are about the size of a poppy seed; you would be very lucky to spot such a small tick. Therefore it is important to also use tick preventatives and vaccination to prevent the spread of Lyme disease. When you find a tick, carefully part the hair so you can see its entire body. If necessary, wet the dog's fur with some water. Use the tool or the tweezers to grasp the tick as close to the dog's body as possible. Once you have a firm but gentle grasp, TWIST the tick around 360 degrees or more and it will let go of the dog. If you try to pull instead of twist, the tick may pull some skin away as you are removing it - ouch! Do NOT try to burn the tick off your pet as this is painful and dangerous! After the tick is removed, wash your hands and the affected bite area with soap and water. Improved Lyme Test (IDEXX Snap® 4Dx Test) Showing Higher Incidence of Lyme Disease ExposureWith the use of the Snap® test, a routine heartworm test also tests for Lyme disease, Anaplasmosis, and Ehrlichiosis. The incidence of Lyme Disease exposure is much higher than previously thought. Heartworm disease is caused by a parasite transmitted from dog to dog by mosquitoes. Lyme disease, Anaplasmosis and Ehrlichiosis are caused by bacteria, and Ehrlichiosis is caused by a parasite, both of which can be transmitted by tick bites. All three diseases occur world wide including this area. Clinical Signs of Lyme Disease:
Clinical Signs of Ehrlichiosis
Clinical Signs of Anaplasmosis
Performing the SNAP® 4Dx test:
Since the symptoms of Lyme disease, Anaplasmosis and Ehrlichiosis are similar to many other diseases, there is frequently a delay in testing for these diseases. With the new Snap® test, the tests can be performed in the veterinary office and the results obtained within 8 minutes. With Lyme disease, previous tests would be positive if a dog had been vaccinated necessitating a second, more expensive test to be performed. The Snap® test however is not influenced by vaccine induced immunity. By routinely testing normal dogs simultaneously with their heartworm tests, many additional cases are being detected, evaluated, and treated earlier in the course of the disease. Idexx C6 Quantitative Lyme TestThe Lyme Quant C6® is a breakthrough laboratory test that helps diagnose, quantify, manage and monitor Lyme-infected dogs as part of a two-tiered approach. Tier 1: SNAP® 4Dx® Screen
Tier 2: Lyme-positive results are followed up with Lyme Quant C6® Test
By utilizing these tools we are able to quickly identify Lyme infection in canine patients and use valuable, measurable information to monitor a treatment choice. |
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Lyme Disease
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