Dr. Anna Dunton-Gallagher
OFF THE LEASH
As I was preparing a presentation on Lyme disease this past week, I realized that there are many misconceptions people have, and so I gathered all of my questions for a Q and A primer on Lyme disease. Because this winter, as previously, we have had many days above freezing and without snow, we are still at a risk for ticks. Tick prevention often falls by the wayside through winter, and unfortunately we must stay vigilant as our winters warm up.
Q- How do dogs get Lyme disease?
Dogs get Lyme disease from being bitten by an infected tick (black-legged/deer tick). The organism that causes what we know as Lyme disease is actually called Borrelia burgdorferi. This is passed from the tick when it is feeding. This organism lives within infected mammals and is spread between them by deer ticks. The tick must feed for 24-48 hours to spread the causative organism to the dog. No other type of tick is known to spread Lyme disease.
Q-How do I know if the tick that bit my dog had the Lyme organism?
There is no way to know this. We can test for Lyme exposure after 21 days. Dogs very rarely get the “bulls-eye lesion” that is so common in people (even if we were to shave their hair!) In Vermont, an estimated 10-20 percent of black-legged ticks carry Borrelia. This is a much higher incidence than ticks in areas of the country other than the Northeast.
Q- Can my Lyme-positive dog give me Lyme disease?
Your dog cannot transmit Lyme disease to you directly. Lyme disease is called a vector-borne disease, which means that it is spread only by its vector. In this case the vector is the tick. However, if there are infected ticks biting your dogs, then that means they are around you. A tick can feed on your dog, detach and then feed on you, which will spread the disease. This is why effective tick control is so important!
Q-What are symptoms of Lyme disease?
Symptoms of Lyme disease include joint pain, lethargy, reluctance to eat, fevers, and can progress to kidney failure. Since it shares many symptoms with other diseases, and many dogs only have one or two symptoms, it can often be mistaken for other things. We always recommend an exam as soon as possible when things seem off with your dog.
Q- Can I prevent Lyme disease?
The best way to prevent Lyme disease is to make sure that your pets have effective tick control. This means a product that will kill the tick when they begin to feed. While repellents can be helpful, it is important to know that a tick will not survive long enough to transmit the Lyme organism.
We also recommend vaccinating for Lyme disease. The Lyme vaccine doesn’t prevent the disease, but lessens the severity of it. It greatly reduces the chance that Lyme will progress to a fatal form or cause debilitating arthritis. A combination of vaccinations and tick prevention gives us about 99.5 percent protection, which is pretty close to perfect.
Q- Can cats get Lyme disease?
Cats cannot get Lyme disease at this point. However, ticks that feed on your cats can still be reservoirs. Cats can be infected and carry the Borrelia organism, but do not show clinical signs. So while we don’t worry about cats becoming sick, we still want to prevent ticks from feeding on them and surviving (since they can then feed on humans, horses or dogs).
Q- Does every positive test in the clinic mean my dog has Lyme disease?
No! This is very important and is a discussion that I have every day. Actually only about 5 percent of all dogs who test positive on veterinary in-house tests have Lyme “disease.” Instead, we know they have had exposure and have created antibodies to try to fight the organism. We must pair this positive with symptoms and other tests to call it “Lyme disease.” While our test tells us “yes” or “no,” there is a blood test that tells us the exact number of antibodies the dog has made.
While we may get a positive with a value of five, it is not recommended to treat dogs that have a value of less than 30. Even more confusing, many dogs will remain positive on the in-house test for years, even if they never have another exposure. The trouble with treating every positive is that we run the risk of creating strains of Borrelia that are resistant to antibiotics. This is in addition to prescribing medicine that isn’t needed. The test serves to help guide us as to what to do next, and lets us know if we need to change our prevention protocol.
Q- What happens if my dog DOES test positive?
The first thing we do is check a urine sample for protein. This is one of the first signs that the exposure is progressing. We also recommend checking the more specific blood test. We will also use this in addition to anything we find on a physical exam to help tell us how to proceed. Unfortunately, these cases are not black and white, but luckily we have many tools for the gray areas. The important thing is that this tells us we need to adapt the tick prevention you are using on your dog.