Lyme Disease in Dogs

Lyme Disease in Dogs

Northern Minnesota has a very healthy population of ticks, making tick borne diseases also prevalent. Lyme disease is the most common tick transmitted disease and is caused by the spirochete bacteria Borrelia burgdorferi. In our area, it is spread by the Deer tick, also known as Ixodes scapularis. Other Ixodes species, found in other regions, also carry the bacteria.

Ticks & Transmission

In order to understand the disease and how it is transmitted, one must study its lifecycle. A host is an animal that has the disease, while a vector is a organism that transports and delivers the bacteria from one host to another. The original host is commonly the Deer Mouse, therefore lending the name to Deer Ticks. In Spring, female ticks lay their eggs, which hatch into larva. Due to their small size, they feed on small hosts such as mice, picking up the Borrelia bacteria and carrying it throughout its life. After a blood meal, they drop off and lay dormant until the following spring, when they molt into a nymph. Similarly, the nymph gets its blood meal from a host, then goes dormant until the following Spring, and molts into an adult. Nymphs and adult ticks can feed on larger hosts such as wildlife, dogs, and humans.

Ticks feed by burying their mouth parts, like a “feeding tube”, into their host. They secrete an anesthetic to keep from being noticed, an anticoagulant to keep the blood flowing, and attach themselves with a cement like substance and barbs to remain in place. Saliva from the tick also flows through the “feeding tube“, which carries the bacteria into the host. For Lyme disease to transmit, the tick must be attached for a minimum of 24-48 hours. Other tick-borne diseases can transmit in less time.


According to the American Veterinary Medical Association, approximately 90-95% of dogs who are exposed do not exhibit symptoms. The ones that do may develop only one or multiple of the following symptoms:

  • Limping/Lameness
  • Stiff joints
  • Swollen joints
  • Swollen Lymph Nodes
  • Inappetence
  • Lethargy/Fatigue
  • Fever
  • Heart & Neurologic symptoms are extremely rare


The test (Idexx 4Dx Snap) that we have at our clinic indicates if there are antibodies that the dog’s body has produced to fight the bacteria. A positive test does not mean the pet currently has the disease, but that it has been exposed to the disease at some point. In order to determine if the dog has an active infection, a C6 Antibody test can be sent to a reference lab. It measures the level of antibodies in the blood to the C6 peptide on the surface of the bacteria. A low level indicates they likely had the disease but either were successfully treated or the body fought it off on its own. A high level means they may presently have clinical disease, and we may need to treat the infection. To determine if the treatment was successful, a follow-up C6 is run 6 months later. If the antibody level has dropped at least 40%, we know the treatment course was sufficient.

Testing the pet immediately after a tick bite will not give an accurate result. It takes weeks for the body to create the antibodies that the test will detect. This is why we recommend yearly testing.


Depending on if the patient is exhibiting symptoms, a positive in-clinic test may signal the veterinarian to prescribe a course of antibiotics or wait for the results of the C6 to determine if treatment is needed. The antibiotic that is chosen most often to treat tick-borne illness is Doxycycline. Improvement can often be seen within a few doses, but the entire course of antibiotics should be given regardless to prevent relapse as well as antibiotic resistance. Other tick-borne diseases have similar symptoms and are also treated with Doxycycline.

Long Term Effects

The Borrelia bacteria like to migrate into joints. Their presence causes inflammation which can cause swelling, pain, limping, and lameness. If left untreated, the inflammation can damage the joints causing chronic arthritis.

The long-term presence of the Borrelia antigens in the patient causes the immune system to remain active attempting to remove it. Over time the antibodies (proteins created to fight the antigens) can deposit in the kidneys causing inflammation and damage. It is important to monitor the kidney function of Lyme positive patients, which may include blood work or testing the urine for protein loss which indicates kidney damage. Canine kidneys are very sensitive, so steps must be taken to slow the progression of kidney disease. If the damage to the kidneys is not caught early, it will likely result in kidney failure. Symptoms of kidney disease can include increased thirst, increased urination, decreased appetite and lethargy.

How Lyme differs from Dogs to Humans

After being exposed to Lyme, 90% of humans will manifest symptoms, while only about 5-10% of dogs will develop any symptoms. Humans commonly see a bullseye rash around the tick bite as well as flu-like symptoms shortly after transmission. Dogs may have some redness around a tick bite, but only because the saliva is irritating and doesn’t mean they have contracted the disease. Dogs may not show symptoms for weeks or months after exposure. The antibiotic dose to treat Lyme also differs greatly in humans versus dogs. Read more about tick bites on our blog.


Tick Prevention- There are many different tick preventives on the market in many forms (collars, oral chews, topicals). There are over-the-counter and prescriptions options, but the prescription options are by far more effective. The purpose is to either repel or kill the ticks before the 24 to 48-hour window of transmitting the disease. These preventives are most effective if they are given ahead of tick exposure and are allowed adequate time to build up in the patient’s system.

Vaccine- There are vaccines available for dogs. The vaccine introduces a modified version of the bacteria so the body can develop the same antibodies it would towards the disease itself. The vaccine we use (Elanco® TruCan™ Lyme) is 92.2% effective against natural infections. Therefore, it is still possible to become infected, even if vaccinated, especially in high endemic areas.

Tick Control- You can reduce the population of ticks in your yard by removing the habitat that ticks love (leaf piles, tall grass, stick piles, etc), keeping you yard well maintained, controlled burns, having a gravel barrier between the woods and yard, controlling the rodent population, and setting out tick tubes in the Spring & Fall. What is a tick tube?

Prevention for Humans

Prevention for your pet doesn’t just protect them, but also your entire family as they are less likely to bring the ticks into your home.

Humans should avoid wooded and tall grassy areas during tick season if you can. If not, wear light clothing so you can see ticks easier, tuck your pants into your socks, spray your clothing with a pyrethrin insecticide spray, and immediately check for ticks when done.


My dog had Lyme disease, can he get re-infected? Yes, they can get re-infected by another tick.

My dog has tested positive, do I need to retest? Yes, thought they will still be Lyme positive, the Idexx 4Dx test doesn’t just check for Lyme disease but also for heartworm, Anaplasmosis, and Ehrlichiosis. After a while the antibodies may decrease, and the patient may test negative for Lyme.

Should my dog who is Lyme positive still get the vaccine? Yes, the vaccine can help prevent them from becoming re-infected and is likely helpful in preventing secondary issues like kidney failure and arthritis. Though, the patient should not be vaccinated if they have symptoms or are currently being treated for the disease.

Can my dog give me Lyme disease? No, it must be transmitted through a tick.

What about cats? Lyme disease has not been studied as extensively in cats as in dogs & humans. Yes, cats can also get Lyme disease, but are much more resistant to the bacteria and are far less likely to develop symptoms. There is no in-house test for feline Lyme disease, but a test can be sent to a reference lab. The Lyme vaccine has not been approved for cats. Cats should be kept on tick prevention if they are outdoors or have dog housemates that will expose them to ticks.

What is an endemic area and are we in one? An endemic area is a region where the disease is consistently present over time. Yes, Northern Minnesota is most definitely an endemic area. The Companion Animal Parasite Council is dedicated to increasing awareness of parasites by collecting credible data and dispersing accurate information to educate pet owners and veterinary professionals. See CAPC map.

If your dog is exhibiting symptoms of Lyme disease, or if you’d like to get them started on preventives, give us a call to schedule an appointment.

Importance of Heartworm & Tick Disease Testing

Importance of Heartworm & Tick Disease Testing

At your dog’s annual exam, the veterinary staff will discuss which vaccines and tests your pet should receive. One of the options we offer is the Idexx 4Dx test which screens for heartworm, Lyme, Ehrlichiosis, and Anaplasmosis. To help make your decision easier, here are some answers to frequently asked questions regarding the test.

What’s involved and how does the test work?

Just a few drops of blood are needed to run this test. It takes about 10 minutes to get results. The test detects antibodies in the patient’s blood to tick diseases. Antibodies are the immune system’s response to the presence of antigens, which are anything foreign to the body including diseases. A positive result on the test means the patient has been exposed to the tick disease, not necessarily that the patient currently has the disease. Further testing may be necessary to determine if the patient needs treatment. Each patient’s immune system is unique, meaning the amount of time the antibodies are present can vary.

For the heartworm part of the test, the antigens are what is detected. A positive result for heartworm then means the patient currently has a heartworm infection. More testing is required to determine the severity of the infection and the treatment needed.

Why run a 4dx test yearly?

Most companies that make Lyme vaccines, heartworm preventives, and flea/tick preventives have guarantees associated with their products. For example, if your pet becomes infected with Lyme disease while using their product or after being fully vaccinated, they will cover the cost of testing and treatment. There are requirements to qualify for the coverage, including proof that the patient was negative before starting the product or getting the vaccine. Also, having a negative test as a base line to compare to when a patient is ill can help determine the diagnostics needed as well as the course of treatment. For both reasons, yearly testing can be financially beneficial to clients.

My dog has already been positive, should I still test?

If your pet has tested positive for a tick disease in the past, they may continue to test positive for a period of time due to residual antibodies. That period of time varies depending on the disease and your pet’s immune response. It will be helpful to know when the patient is negative, meaning the residual antibodies are gone. The next time the patient tests positive, it will be clear that it is a new infection.

There are more specific tests that can measure the number of antigens in the patient. For example, a Lyme C6 gives you a quantitative number which determines whether the patient is fighting a current infection vs presence of residual antibodies.

Additionally, if they were positive for one disease it is still useful to test for the other three diseases. Given the high density of ticks in our area, we see patients with concurrent infections of more than one tick disease. The tick diseases also share some symptoms, so the test will determine which one the patient is fighting.  

My pet is already on heartworm or flea & tick meds, why do I need to test?

Unfortunately, no product has 100% efficacy. There is still a chance, though a very small one, that your pet could contract a tick disease while on tick preventives or heartworm disease on heartworm preventives. Also, if your pet travels with you to the southern United States, it may be exposed to a species of heartworm that is resistant to an active ingredient in some heartworm preventives. Therefore, it is best practice to test even if your pet is on year-round prevention.

If you have any questions, the staff at Northern Veterinary Clinic is here to answer them. Your pet’s annual exam is a perfect time to address any issues and concerns. Give us a call at 444-5797 to schedule an appointment.