What is Lyme disease?

Lyme disease is caused by a bacteria called Borrelia burgdorferi that is spread by the black-legged tick, often referred to as the deer tick. Basically, Lyme disease can be transmitted to dogs, cats and people when an infected tick attaches itself to their skin for a blood feast. An infected pet cannot transmit Lyme disease to a human. These ticks are extremely small, varying in size from a sand granule to a sesame seed.  Because the deer tick is so tiny, it may bite animals and people and not be detected immediately. This is why prevention is so important.

Risk Factors

While your pet dog may carry a tick into the house, a tick that has attached to a dog will feed and drop off, and thus is not risky. Once fed, it will not feed again for at least a month. By that time, in typical households, the engorged tick will have dried up and died. Where you might find a greater risk is with your cats. Since ticks don’t like to feed on cats as much, it may drop off in the home (in the owner’s bed or lap) and reattach to a human.

When it comes to companion pets, cats have not been shown to develop illness after being infected with the Lyme bacteria. Therefore Lyme disease is not recognized as a health concern for cats. Dogs, on the other hand, may become ill after being bitten by a tick carrying the Lyme bacteria. Because dogs are exposed to ticks anytime they go outside, due diligence to prevent  infection is necessary.  Your dog is at higher risk for getting Lyme disease if he/she lives in an area with a high incidence of human Lyme disease. With all the hype around human Lyme disease, it should come as no surprise to New Englanders that we are at a higher risk in this region. In fact, researchers at the Yale School of Public Health have developed a prevalence map, which reinforces that there is a clear risk of Lyme disease across much of the Northeast, from Maine to northern Virginia.

Individuals and pets who live or work in areas surrounded by woods or dense brush, where deer and mice reside, and in particular those who engage in lots of outdoor activities in these areas, have a greater risk of contracting Lyme disease. The highest risk for your pets is late spring through fall.

Prevention

An important element of any successful tick control program lies in your own backyard. Mow your lawn regularly, remove tall weeds and make it less inviting to rodents by keeping garbage covered and inaccessible. These other activities will also be helpful in your prevention regimen:

• Use a veterinarian recommended tick preventive. It’s important to note that topicals do not prevent the ticks from getting on the dog (e.g., it is not a repellent).  Ticks may actually live for a few hours feeding on a dog. This does not mean the preventive treatment has failed, but that there is a delayed action. The tick will eventually die.
• Talk to your veterinarian about vaccinating your dog against Lyme disease (see below for more information)
• Check for ticks daily (if your cat does go outside, be sure to check too). Feel for bumps, look down to where the fur meets the skin. Be sure to look under legs, in ears, etc. Brushing might also be helpful.
• Ask your veterinarian to conduct a tick screening at each exam
  • Practice protective measures yourself. The very act of walking in the woods with a dog might expose you to ticks; thus, owners need to institute their own preventive practices.  That may include applying repellent, treated clothing, showering immediately after being outside, regular tick checks, and just being aware of signs and symptoms and the potential need for medical attention.

The Connecticut Agricultural Experiment Station has a Tick Management Handbook that you can download for free, summarizing great ways to reduce risk. Additionally, the University of Rhode Island’s Tick Encounter Resource Center’s website offers a comprehensive summary for preventing and protecting against Lyme disease.

Removing Ticks

Since it can take 24 to 48 hours for an attached tick to transmit an infection to its host, prompt and proper removal is helpful in preventing disease onset.

Step 1: Get your supplies (pair of gloves, clean pair of tweezers or a commercial tick remover, antiseptic and rubbing alcohol)

Step 2: Remove the tick

• Wear gloves to avoid tick coming in contact with your skin since ticks can transmit diseases to people, too.
• If you’re using tweezers:
  Grasp the tick as close to your dog’s skin as possible. Pull outward in a straight, steady motion, doing your best to remove the entire tick.  Don’t worry about any portion of the tick that might remain in the skin. The animal’s body will destroy, scab over, and remove any small remains. Digging into the animal’s skin with tweezers, etc., and trying to remove remaining parts of the tick may cause harm.
• If you’re using a tick remover:
  Gently press the remover against your dog’s skin near the tick. Slide the notch of the remover under the tick. Continue sliding until the tick is caught in the small end of the notch and is pulled free.

While tick removers are available, many clinical experts find that plain tweezers work just fine.

Step 3: Store the evidence
Drop the tick into a container of rubbing alcohol, which will quickly kill the tick. OR if you don’t put it in alcohol, scotch tape the tick to an index card and write the date on it and store in plastic bag. If your dog begins displaying symptoms of a tick-borne disease, your veterinarian may find the evidence useful to make a diagnosis.

Step 4: Clean the tick bite
Use antiseptic on the tick bite.  Clean the tweezers or tick remover with rubbing alcohol and be sure to wash your hands too.

Step 5: Follow up
Watch the area where the tick was for signs of infection or irritation. If the site shows signs of this, make an appointment with your veterinarian.

Clinical Signs      

Animals are infected by the Lyme disease bacteria, but don’t always show signs or symptoms. They may test positive, but seem completely healthy.

The clinical signs in dogs vary and are non-specific. The characteristic rash associated with humans is not seen in dogs.  The most commonly reported signs in dogs include:

• Fever
• General malaise and loss of appetite
• Swollen lymph nodes
• Recurring shifting-leg lameness due to inflammation of the joints (e.g., lameness in one leg, with a return to normal function and then recurring in the same or other leg)
• Swollen, painful joints where dog may be reluctant to move

Even though lameness is a common symptom of canine Lyme disease, the crippling and long-term arthritic symptoms experienced by humans is also not common. Some dogs with Lyme disease may develop kidney disease. Signs can include depression, vomiting, loss of appetite, and increased thirst and lack of urination. Dogs who develop kidney disease can become very ill and may not respond to treatment.

Neurological disease (behavioral changes, seizures) and heart complications, which are sometimes seen in humans, are rare in dogs.

Clinical Signs in Cats
Lyme disease has not been documented to cause signs of illness in cats. Although cats are exposed to the organism, and develop antibodies in their blood against B. burgdorferi, no signs of illness have been observed.

Diagnosis

If your pet is exhibiting any of these symptoms and/or you suspect he/she may have been infected, you should consult your veterinarian. Since most diagnostic tests rely on detecting antibodies in the blood, and the symptoms are fairly non-specific, Lyme disease is difficult to diagnose soon after infection. It could take four to six weeks to become detectable. Rather than wait, your veterinarian may begin treatment to see if that has any effect of the symptoms.

Testing in the absence of signs and symptoms should be discouraged. It is not clear that a positive “Lyme test” requires any intervention if a dog appears healthy.

Treatment

If the diagnosis is Lyme disease, there are a number of antibiotics from which to choose, doxycycline being the most commonly prescribed. The recommended period for treatment is several weeks and most respond quickly to treatment and symptoms may improve in as few as 24-48 hours.

Vaccinating Against Lyme Disease

To vaccinate or not, that is the question. Vaccination against Lyme disease is a controversial topic and is something that should be discussed in depth with your veterinarian to see if it is right for your pet. Michael Stone, staff veterinarian and clinical assistant professor at the Cummings School addresses the question of vaccination in dogs in this “Ask the Expert” article.

If you have any questions or concerns about your pet, you should always contact your veterinarian. They will be your most informed resource on the health and safety of your pets and how best to protect them.

Reference Sources:
About.com Veterinary Medicine
http://vetmedicine.about.com/od/diseasesandconditions/a/CW-K9Lyme.htm
Pet MD
http://www.petmd.com/dog/conditions/infectious-parasitic/c_dg_lyme_disease
The American Society of Tropical Medicine and Hygiene (ASTMH)
http://www.astmh.org/Feb_2012_press_release.htm
Pet Health Network
http://www.pethealthnetwork.com/dog-health/lyme-disease-dogs
The Humane Society of the United States
http://www.humanesociety.org/animals/dogs/tips/getting_ticks_off_dog.html
Pet Shed
http://www.petshed.com/petcyclopedia/all-about-lyme-disease-in-dogs.html