Ticked Off

What do I need to know about Lyme disease?

Lyme disease is a bacterial illness that can be transmitted to humans, dogs and other animals through the bite of infected blacklegged ticks, such as deer ticks. It is called Lyme because the first number of cases were recognized in Lyme, Connecticut, in 1975. Spring is the season when ticks become active. It is important to know how to protect yourself and your dogs against this potentially dangerous disease.

Deer ticks are found throughout the Midwest and eastern United States, as well as Canada, with the highest numbers coming from Ontario. Unlike fleas that jump onto their hosts, the ticks that carry Lyme disease can only crawl. They are likely to be found in tall grasses, thick brush, marshes and woods. This enables them to passively latch onto your dog or your leg when you brush by. A tick must be attached for 24 to 48 hours in order to transmit the disease.

The bacterium that causes Lyme disease is Borrelia burgdorferi. It is a spiral-shaped organism known as a spirochete. Once in the bloodstream, the Lyme disease organism is carried to many parts of the body. It is most likely to accumulate in bone joints or kidneys.

Can my dog spread the infection to another dog or my family?

Direct spread of Lyme disease from one dog to another dog has not been reported, even when infected and uninfected dogs have lived together for long periods. The spread of Lyme disease from dogs to people has not been reported, either. In order for dogs or people to contract Lyme disease, they must be bitten by an infected tick. You could become infected indirectly when you come into contact with a carrier tick brought in on your dog’s fur.

If your dog is diagnosed with Lyme disease, you and your other dogs have probably been in the same area and also been exposed. It is a good idea to consult with your physician and veterinarian to see whether you should be tested, as well as other pets and family members.

What are the symptoms of Lyme disease in dogs?

People with Lyme disease may develop a “bullseye” rash at the site of the tick bite within three to 30 days. When the red rings occur, the disease can be easily diagnosed at an early stage.

Signs of Lyme disease in dogs are more difficult to detect. It has been called “the Great Imitator” since the symptoms mimic that of other conditions. The typical rash does not develop on dogs.

Many dogs affected with Lyme disease experience swollen, painful joints, a decrease in appetite and weight loss. They may be limping and running a high fever. This lameness can appear suddenly and may shift from one leg to the other. If left untreated, the symptoms can disappear, only to recur weeks or months later.

Some dogs are infected with the Lyme disease organism for more than a year before they finally show any signs. By this time, the disease may be widespread throughout the body. Kidney failure, and heart and neurologic disease can develop over time as the disease progresses.

Less commonly, dogs will develop an inflammation of the kidneys that leads to protein loss and the progressive destruction of the kidneys. This reaction, called Lyme nephritis, may continue with devastating consequences even after the infection is cleared.

How is Lyme disease diagnosed in dogs?

The traditional blood tests for Lyme disease, including PCR, ELISA, Western Blot and joint fluid analysis, have been replaced by two new tests called the C6 test and Quantitative C6 test (QC6). The C6 is a preliminary blood test that detects antibodies against a very specific protein called C6. This protein is unique to the Borrelia bacteria. The presence of antibodies to C6 suggests exposure to Borrelia and infection.

The C6 antibodies can be detected as soon as four weeks after a dog is bitten by an infected tick. These antibodies may be found in the bloodstream even before the dog shows signs of illness. The C6 is often offered as part of a special test kit that checks for other tick-borne diseases, such as Ehrlichiosis and Anaplasmosis. The test can be done by your veterinarian “in-house” or the blood sample can be sent to an outside laboratory.

The C6 test can be falsely negative if the dog is infected, but has not yet formed antibodies, or if the dog never forms enough antibodies to cause a positive reaction. It is recommended to test no earlier than four weeks after a tick bite.

Some dogs that have been infected for long periods of time may no longer have enough antibodies present to be detected by the test. This means a positive test is meaningful, but a negative test is not. Blood samples should be sent to the laboratory for confirmation if Lyme disease is suspected but the test is negative.

A positive C6 test means that antibodies to C6 were found. The next step is to do a QC6 test, or Quantitative C6 test, to determine if the levels of antibody are high enough to justify treatment. If the value of the QC6 is higher than 30 IU/mL and signs of illness are present, treatment is recommended. If the QC6 is less than 30 IU/mL and there are no symptoms of illness, then treatment may not be necessary.

In addition to doing a QC6 test, your veterinarian may want to take blood and urine samples to evaluate kidney function and look for protein in the urine. A positive test for protein in the urine could signal serious underlying kidney disease.

What is the treatment for Lyme disease?

The Lyme disease spirochete is a bacterium, so the disease is treated with antibiotics. The antibiotic of choice is doxycycline, but amoxicillin or azithromycin may be prescribed for dogs that do not tolerate the doxycycline. Treatment lasts for three to four weeks.

Symptoms usually resolve quickly once the antibiotic treatment is started. Occasionally, the initial infection will recur, or your dog may become re-infected if he is bitten by another disease-carrying tick.

How can I tell if the treatment is working?

If your dog is limping or has swollen joints, improvement is usually seen after three to five days of starting antibiotics. A dog’s response to therapy can be assessed by repeating the QC6 test six months after treatment is complete. Dogs that start with a moderate to high QC6 value typically show at least a 50 percent reduction in the QC6 at six months, indicating that treatment has been successful.

Dogs that have a lower initial QC6 may not show such dramatic reductions in the QC6 at six months, although the value should still be lower than the starting level if treatment has been successful. A persistently high QC6 suggests treatment may not have been complete or that the dog has become re-infected after treatment was stopped.

How can I prevent my dog from getting Lyme disease?

The key to prevention is keeping your dog from being exposed to ticks. After walking in grassy, wooded or sandy areas, you should carefully examine your dog and yourself for ticks. Wear gloves or use a tissue to protect your fingers when removing ticks. If you crush the tick, make sure you do not get the tick’s blood on your skin.

There are many products available for your dog to repel and kill ticks as well as prevent disease transmission. Some are applied topically and some are given orally. Check with your veterinarian for specific recommendations that will best protect your dog.

A safe and effective vaccine against Lyme disease is available for dogs. This vaccine is initially given twice at a two- to four-week interval. Annual revaccination is necessary to maintain immunity. The need for vaccination against Lyme disease is determined by your dog’s lifestyle, environment and individual risk assessment. If you live in an area where ticks are prevalent and your dog will be exposed, it makes sense to have your dog vaccinated.