Lyme disease is a tick-borne disease that affects both dogs and people.
You cannot get Lyme disease directly from your dog. But you can get Lyme disease from the same ticks that transmit the disease to your dog. This fact makes Lyme disease an important disease for both of you.
What is Lyme Disease?
Lyme disease is passed to you or your dog by the bite of an infected tick. The disease itself is caused by a bacteria known as Borrelia burgdorferi. Lyme disease is more common in some geographical areas than in others. Your veterinarian should be able to tell you how prevalent Lyme disease is in your area.
What are the Symptoms of Lyme Disease in Dogs?
Lyme disease in dogs is entirely different in its presentation compared to Lyme disease in people. The most common symptom of Lyme disease in dogs is lameness and joint pain. This lameness may shift from one leg to another. Fever may also be seen.
A more serious form of Lyme disease involves glomerular damage, a form of kidney disease. This form of Lyme disease can become life-threatening and is much more dangerous for your dog. It is believed to be an immunologic reaction to the Borrelia organism’s long-term presence.
In dogs, the heart problems (arrhythmias) and neurologic symptoms seen in some people occur very rarely.
How is Lyme Disease Diagnosed in Dogs?
There are readily available blood tests that can detect antibodies to the Borrelia burgdorferi organism. The most commonly used test is the C6 peptide test (also known as the SNAP3DX or the SNAP4DX test. Though these specific tests also check for other tick-borne diseases as well.) The C6 peptide is part of a protein on the organism’s outer surface—Osp.
Borrelia burgdorferi can express various Osps depending on where the organism is attached. For instance, if the organism is attached to the midgut of a tick, the Osp expressed is different than that expressed if the organism is attached to the connective tissue. The Osp can also change depending on the stage of infection in mammals. However, the C6 peptide remains present regardless of the Osp being expressed. As a result, it is almost always detectable, unlike antibodies to the individual Osps. In addition, the C6 peptide is not part of the vaccinations available against Lyme disease. Vaccination will not result in a positive Lyme disease test.
Positive results in healthy dogs
The confusion about Lyme disease arises from the fact that many dogs have positive tests without being sick. In the Northeastern United States, it is estimated that as many as 90% of dogs have antibodies to Lyme disease and thus have positive Lyme disease tests. However, very few dogs actually develop symptoms of the disease. Further, antibodies can persist in the bloodstream for years. This makes it difficult to distinguish active infection from inactive and not currently causing disease. It also creates a quandary in deciding whether to treat the dog or not.
Treatment for Lyme Disease in Dogs
If your dog is showing signs of Lyme disease, there is no doubt that he should be treated. Lyme disease normally responds very well to treatment with antibiotics. The most commonly used is doxycycline, but other antibiotics such as penicillins are also effective.
Dogs suffering from the glomerular (kidney) form of the disease will likely need much more aggressive treatment aimed specifically at treating kidney disease, in addition to antibiotics. This form of Lyme disease carries a much more guarded prognosis than the more commonly seen lameness with or without fever.
To treat or not to treat
The confusion regarding treatment arises when a dog tests positive for Lyme disease without showing any signs of disease. Some veterinarians recommend treating with a course of antibiotics in this situation. However, it is not reasonable to expect to clear the organism from the dog’s body when treating Lyme disease in dogs. The Lyme disease organism has an uncanny knack for hiding, even from the dog’s immune system, because of its ability to change its Osp proteins.
In addition, tests can remain positive for years even in inactive infections. As a result, the treatment of healthy dogs with positive Lyme disease tests is controversial. Presently, it is unknown whether the treatment reduces the chance of the organism causing disease. More research is needed in this area before a definitive answer to this question can be formulated.
If your dog tests positive for Lyme disease but is clinically healthy, it is important to monitor proteins in the urine regardless of whether you and your veterinarian elect to treat your dog for Lyme disease. Protein leaking through the glomeruli and into the urine is one of the early indicators of impending kidney disease and will be detectable before clinical signs appear. (Glomeruli are part of the filtering apparatus of the kidneys.)
Available testing today
Standard antibody testing
The standard testing at the root of the above confusion involves testing for Lyme antibodies. Culture and PCR are an option but difficult and complicated.
Because these tests look for antibodies, they can give false-positive results. These tests are useful for initial screening, but to avoid the above dilemma, you can follow up with a newer test.
Lyme Quantitative C6
When the standard test is positive for exposure to Lyme, the Lyme Quant C6 test helps determine the difference between exposure and active infection. C6 antibody is present only during infection. These results are more specific, though not perfect.
Serologic testing is a new kid on the block that might offer conclusive answers to Lyme disease testing. The tests in the working include:
- Cornell’s Multiplex assay
- Anthech’s AccuPlex4
- Abaxis ELISA quantitative Lyme test
Further reading: Lyme disease Part I: Transmission, Pathophysiology & Testing
Prevention of Lyme Disease
The most effective way to prevent Lyme disease is to prevent your dog from getting ticks. Here are some of the ways that you can do that.
- Avoid taking your dog into tick-infested areas.
- Check your dog regularly for ticks and remove them promptly when you find them.
- Consider using a monthly topical medication to prevent ticks.
There are vaccinations available against Lyme disease and your veterinarian may recommend that your dog is vaccinated if he is at risk. However, vaccination against Lyme disease remains controversial and not all veterinarians recommend its use.
Vaccination against Lyme disease does not preclude the need to prevent ticks. There are other, even more dangerous, tick-borne diseases, and the vaccine does not prevent those diseases.