What is Lyme Disease?
Lyme Disease is a condition caused by the bacteria Borrelia burgdorferi and is transmitted to humans and dogs through the bite of infected black legged ticks. Most people that get exposed to the Lyme bacteria get sick with symptoms ranging from fever and fatigue to infection in the joints and nervous system. What we see in dogs is different. Current studies demonstrate that 80-95% of dogs exposed to the bacteria never show signs of disease. Because most of our canine patients don’t get clinically ill from infection, veterinarians talk about two different conditions in dogs; being exposed to the Lyme bacteria versus having Lyme Disease.
Dogs that do get sick from Lyme bacteria most commonly will have lethargy, fever and sore joints. However, there is a very serious and rare complication of Lyme Disease that can affect the kidneys, called Lyme Nephritis. In this disease, an autoimmune problem develops in the kidneys triggered by the Lyme bacteria. Dogs with Lyme Nephritis can have vomiting and poor appetite. Their kidneys can go into failure quickly and there are limited treatment options. Lyme Nephritis is fatal if a dog develops this complication.
How is Lyme Disease Spread?
Lyme disease is spread through the bite of blacklegged ticks. In our area, the black legged tick that spreads disease is Ixodes scapularis, the deer tick. When an infected tick takes a blood meal it injects the bacteria into its host. It takes 24-48 hours for the bacteria to travel from the tick to the dog.
Deer ticks live several years. Adults lay eggs in the late spring and summer which hatch into larvae. If the larvae take a blood meal from an infected host, they can over winter with the bacteria in their system. In the spring, the larvae molt into the nymph stage. The nymph ticks will search out a blood meal from a host like a deer, human or dog. The nymph ticks are the size of a poppy seed. They are very small and easy to miss on inspection and because of this they are the most common culprits in causing disease. The nymphs will become active as soon as the temperatures get above freezing. It is important to know that the ticks can be out even when there is snow on the ground.
Do species other than blacklegged ticks carry Lyme Disease?
There are anecdotal reports that other species, such as spiders, can transmit Lyme Disease. These reports are as yet, unsubstantiated. The only proven vector of Lyme Disease are blacklegged ticks.
What is the Incidence of Lyme Disease in Minnesota?
The Center for Disease control reports 1,174 confirmed cases and 631 probable cases of Lyme Disease in people 2015. The Companion Animal Parasite Council, an organization which collects data from veterinary testing laboratories, reports that in 2015, 10,524 of 128,224 dogs (1 out of every 12 dogs) tested were positive for Lyme bacteria in Minnesota.
My veterinarian told me that my dog’s Lyme test came back positive, what does that mean?
Many veterinarians perform an annual test on dogs that checks for Heartworm Disease, as well as exposure to tick diseases, like Lyme Disease. The tick disease part of this test is an antibody test. If your dog gets exposed to the Lyme bacteria, his body will mount an immune response to that bacteria and produce antibodies in an effort to fight off infection. When antibodies are found in your dog’s blood sample, this triggers a positive test. A positive test shows up as a “blue dot”. The darker the blue dot, the more antibodies have been found in the blood.
A positive test doesn’t mean that your dog has an active Lyme infection, it means that your dog got exposed to the bacteria. It can take several weeks for this test to become positive after exposure to the Lyme bacteria, and once it is positive, it can stay positive for many years to come.
What should I do if the test is positive?
There is controversy in the veterinary community about what to do with a positive Lyme test. If the dog is not showing any signs of disease, many veterinarians recommend no specific treatment. My personal recommendation to dog owners with a positive test is to have the dog’s urine screened for any evidence of kidney disease. If this is negative, then I recommend just good tick control going forward. If the urine tests are abnormal, then I recommend antibiotic therapy and diligent monitoring of the kidneys. I do have colleagues that will recommend a course of antibiotics whenever the test is positive. The rationale being that there is likely subclinical disease processes that are happening in the dog. Because there is not one right answer, each veterinarian needs to evaluate the available data and make the recommendation they feel most comfortable with.
Why is it important to run this test if you don’t always treat with antibiotics?
There is value in knowing if your dog has been exposed to the Lyme bacteria for a number of different reasons. We still don’t fully understand what happens in a canine patient when they are exposed to this bacteria. We think that once exposed, the patient is never truly rid of the bacteria. It is possible that a patient may experience symptoms of disease months to years after initial exposure. Because of this, knowing that your dog has been exposed is useful information if your pet begins to experience vague signs of illness that are not easily attributed to some other disease. Also, from a public health stand-point, if your dog has been exposed to the Lyme bacteria, chances are that the people in the household are also going into this same area. It is important that you use good tick control on your dog, and check yourself for ticks very carefully, especially when going into the woods where you might brush against grass and bushes where ticks lay in wait for a host.
What is the treatment for Lyme Disease?
There are several different antibiotics approved for use in treatment of Lyme Disease. My favorite antibiotic for this condition is doxycycline. This antibiotic is unique in that it also has some anti-inflammatory properties which can help with symptom relief.
Are certain breeds at higher risk of getting sick from Lyme Disease?
There are several studies to show that certain breeds, such as Labradors or Golden Retrievers, have a higher risk of developing illness from Lyme bacteria. However, these breeds are also used frequently for hunting, and therefore are also at an increased risk of exposure to ticks and Lyme bacteria.
How do I protect my dog against Lyme Disease?
There are 3 layers of protections against Lyme Disease:
- Check for ticks. After you have been out on a walk, brush your pet’s coat to check for ticks.
- Use a tick preventative medication. If your dog has a thick coat, it can be challenging to find ticks, especially the nymphs which are very small. There are many effective tick control products. Topical products like Frontline, tick collars like Seresto, and oral medications that are given monthly, like Nexgard are all very effective. It is important to start using the tick products early in the season, as soon as the temperatures get above freezing. Also, using tick products on your dog will help protect the people in your house. We want to minimize the risk of your dog carrying ticks into the house that later will crawl onto a person.
- Have your dog vaccinated for Lyme Disease.
Does the vaccine against Lyme Disease work?
Many different companies make vaccines against Lyme Disease and they are all very effective vaccines.
If my dog has already been exposed to Lyme bacteria, should I have him vaccinated?
There is controversy about this in the veterinary community. One school of thought is that dogs that are positive and apparently healthy are managing the bacteria well by virtue of not showing any clinical signs, and therefore do not need to be vaccinated. Proponents of vaccinating Lyme positive dogs do so because they want to try to protect against future infections.
Why don’t they have a Lyme vaccine for people?
Many years ago a Lyme vaccine was available for people, but several people made claims of developing symptoms of Lyme Disease after receiving the vaccine, and it was pulled from the market.
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