Lyme disease is transmitted in the United States by 2 species Ixodes ticks. The first is found east of the Rocky Mountains known as the blacklegged or deer tick, the other is the western blacklegged tick and it is found west of the Rockies. These ticks transmit the bacteria Borrelia burgdorferi via a bite to the host (dogs, horses, humans and possibly cats). It is important to note that no matter the lifestage of the tick if the tick bites a host it is possible for them to become infected. It takes 24 – 48 hours for a tick to transmit the causative bacteria to the host therefore removal as soon as possible is important. During the spring and fall the risk of transmission increases as both nymph stage and adult ticks are actively seeking hosts. Diseases transmitted in this way are called vector borne diseases.
Both species of ticks are very small, less than ⅛ of an inch in length as adults, are reddish brown in colour with a darker brown spot toward the head of the tick. These ticks are typically found living in tall grasses so a complete body check of your pet is a good idea after a hike.
Symptoms of Lyme disease include but are not limited to fever, loss of appetite, painful or swollen joints, intermittent lameness, enlarged lymph nodes, and lethargy. In cases where Lyme disease is left untreated it can lead to kidney, nervous system, and heart damage (however the latter is very rare). While lameness, fever and general malaise are the most common symptoms kidney damage is the second most common syndrome seen in dogs and should be taken very seriously. Many animals however are asymptomatic.
A diagnosis of Lyme disease is often based on clinical signs, patient history as well as the positive test. This test can be performed in house or sent to an outside laboratory. The in house test requires a small amount of blood and can be performed in under 15 minutes. It tests for the presence of antibodies only produced with Borrelia burgdorferi infection. A complete blood count as well as a comprehensive chemistry may also be performed; it is not uncommon for the results of those tests to be normal.
A 4 week course of antibiotics is typically utilized in all dogs that test positive or show signs of Lyme disease. In animals with limb and joint symptoms the response to treatment is usually rapid, but in some cases signs persist and require a second course of medication. Some dogs may experience life long chronic joint pain due to damage caused by the bacterial infection.
Avoidance of exposure to ticks is key to preventing Lyme disease. There are a number of commercially available products to help limit exposure to tick bites. Some medications kill the tick on contact with the pet, some kill the tick after it has procured a blood meal from the pet. As with any medication consistency in administration is very important to maintain your pet’s safety. There is a vaccine available to prevent Lyme disease, this is most useful in animals that have not previously been diagnosed with Lyme or in areas where Lyme disease is common.