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.