Jun 18 2014

Ticks and Lyme Disease

Nicole Jewett and Dan Cartwright

Lyme disease is caused by the bacteria (of the spirochete class) Borrelia burgdorferi and is transmitted by ticks.

In North America, the main carriers for B. burgdorferi are Ixodes scapularis (eastern black-legged tick) and Ixodes pacificus (western black-legged tick). These ticks are also commonly known as deer ticks.  Ticks are most abundant in the spring and fall seasons.

ticks

The immature ticks get infected with B. burgdorferi from wild rodents when feeding in nature and then transmit the infection to other hosts (such as our pets) after these ticks mature.

In the wild, adult I. scapularis and I. pacificus feed primarily on deer. Theoretically, if a given area has a large population of deer, there will be a large population of ticks.

Pets can become infected with B. burgdorferi by the tick as it feeds. Ticks are not able to transmit the infection immediately upon attachment, but instead need to be feeding for approximately 24 to 48 hours before the bacteria can be passed from the tick saliva to the pet.

Unlike humans, dogs are relatively resistant to Lyme disease. Approximately 95% of dogs that become infected with B. burgdorferi will never develop symptoms of Lyme disease. In the 5% that do become sick, symptoms (which usually occur 2-5 months after the infection) can be quite varied. Typical symptoms include:

  • shifting-leg lameness
  • arthritis/swollen joints
  • lethargy/depression
  • fever
  • enlarged lymph nodes
  • loss of appetite
  • kidney infection (nephritis)

There is currently no test that can diagnose Lyme disease. The only test available indicates exposure to the bacteria B. burgdorferi. The test of choice is the SNAP 4Dx. The test, which also tests for 2 other tick diseases as well as heartworm, can be run in the hospital with only 3 drops of blood. Results are typically available in 30 minutes. If a dog tests positive but shows none of the symptoms, we will monitor for symptoms and recommend a urine test to look for protein loss. If the dog is showing some of the symptoms, we may decide to pursue further testing and begin treatment with an antibiotic.

Why do we recommend screening for B. burgdorferi?

  • To look to see how prevalent/common the bacteria is in a given area.
  • A positive test is a marker for tick exposure and increases the awareness for other tick-borne diseases.
  • It helps us measure the success of tick control and prevention methods.
  • Testing provides for a marker for possible human exposure.

My pet has a tick attached, now what?

Attached ticks found on pets should be promptly removed to prevent transmission of Lyme disease or any other diseases they may carry. To minimize your exposure and the accidental infection of your pet during the removal process, ticks should be removed using forceps or a commercial tick-removal device (Tick Twister). Care should be taken to avoid contact with tick contents, ideally by wearing gloves. It is a good idea to wash your hands well after handling the tick.

Once you have removed the tick, place it in a container/baggy with a moistened cotton ball. You can submit the tick to our hospital and for a small fee, the tick will be sent to the Provincial Veterinary Lab in Fredericton to be identified. If it is identified as an Ixodes scapularis tick, it will be forwarded, at no additional charge, to Winnipeg for B. burgdorferi testing. Results usually come back in 6-8 weeks.

Prevention

Tick infestations and resultant infection with B. burgdorferi can be prevented by avoiding tick-infested areas whenever possible and by modifying the habitat around your home through such basic measures as keeping shrubbery and grass closely clipped to discourage both tick populations and the wildlife species that often harbor them from flourishing.

Daily tick checks are also important. This involves thoroughly checking your pets for ticks every day and removing them promptly.

Tick prevention products such as Revolution®, K9 Advantix II®, Preventic® Tick Collars, pyrethroids (i.e permethrin), etc. are available. Some of these have a repellant effect while others will kill the tick once it is attached and feeding.  A vaccine is also available to prevent Lyme disease in high risk individuals.

Key Points

  • Dogs are generally fairly resistant to Lyme disease.
  • Lyme disease can be treated if caught early.
  • Prevention of tick attachment and/or prompt removal is strongly recommended.
  • Submitting ticks for testing found on your pet will help us determine the risk for both our pets and ourselves.

If you have questions or concerns and wonder which are the best tick prevention/control strategies for your pet, please contact your veterinarian.

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