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Care Guide

About Care Guides[x] These care guides are written to help your clients understand common conditions, tests, and procedures, as well as to provide basic information about pet care. They are based on the most up-to-date, documented information, recommendations, and guidelines available in the United States at the time of writing. Pharmaceutical product licensing, availability, and usage recommendations are based on US product information. Use the Download Handout button to generate a PDF for printing or e-mailing to your clients.

Heartworm Disease/Lyme Disease/Ehrlichiosis/Anaplasmosis “SNAP” Testing in Dogs

    • Using a single test, your veterinarian can check for any combination of the following diseases, including all of them: heartworm disease, Lyme disease, ehrlichiosis, and anaplasmosis.
    • All of these diseases are transmitted by parasites. Heartworm disease is spread by mosquitoes; Lyme disease, ehrlichiosis, and anaplasmosis are carried by ticks.
    • Testing takes only a few minutes and requires only a small sample of your dog’s blood.
    • Sometimes, follow-up testing is recommended. This may involve sending a blood sample to a laboratory for further analysis.

    What Are Heartworm Disease, Lyme Disease, Ehrlichiosis, and Anaplasmosis?

    Heartworm disease is caused by the parasitic worm Dirofilaria immitis. These parasites are transmitted (as microscopic larvae) through the bite of an infected mosquito and eventually live and grow in the lungs and heart of infected dogs. Although heartworm disease is not always fatal, some dogs develop permanent damage to their heart and lungs, which can result in heart failure and death.

    Lyme disease, ehrlichiosis, and anaplasmosis are known as tick-borne diseases because they are transmitted when ticks bite and feed. Because ticks can carry more than one of these diseases, and dogs can be bitten by multiple ticks, infection with Lyme disease, ehrlichiosis, and anaplasmosis can occur at the same time in the same dog.

    What Are the Clinical Signs of These Diseases?

    Some dogs infected with heartworm disease don’t develop any obvious clinical signs. In other cases, clinical signs can include coughing, weight loss, and breathing problems.

    Dogs infected with Lyme disease, ehrlichiosis, and anaplasmosis may also fail to display any clinical signs. For dogs that develop clinical signs, the diseases can look very similar. Signs can include fever, lethargy (tiredness), and lameness or joint pain. Research has shown that if a dog is infected with more than one of these tick-borne diseases at the same time, the likelihood of developing clinical signs is increased.

    How Are Dogs Tested for These Diseases?

    “SNAP” testing refers to a group of quick, convenient, blood tests that can be performed at your veterinarian’s office. There are various SNAP tests for different purposes:

    • SNAP Heartworm RT Test—screens for heartworm infection
    • SNAP 3Dx Test—simultaneously screens for heartworm disease, Lyme disease, and ehrlichiosis
    • SNAP 4Dx Test—simultaneously screens for heartworm disease, Lyme disease, ehrlichiosis, and anaplasmosis

    SNAP testing is very accurate and is a good way to identify dogs that may be infected with one or more of these diseases. SNAP testing is also very convenient because it uses a very small amount of blood and takes only a few minutes to perform.

    In some cases, your veterinarian may recommend additional testing to follow up a SNAP test result or to look for other evidence of illness related to heartworm disease or one of the tick-borne infections. Testing may involve sending additional blood samples to a laboratory for further analysis or performing other diagnostic tests to gain more information about your dog’s condition. 

    Why Should My Dog Be Tested for These Diseases? 

    Although heartworm disease is more common in some areas of the country than in others, the infection has been diagnosed in every state in the United States. This means that all dogs, no matter where they live, are at risk for exposure to heartworm infection. Your veterinarian may recommend heartworm testing before your dog begins receiving heartworm preventive medication. Periodic heartworm testing is also recommended throughout your dog’s life—even for dogs receiving heartworm preventive medication year-round.

    Tick-borne diseases like Lyme disease, ehrlichiosis, and anaplasmosis pose a risk to dogs in many areas of the country. Because clinical signs are not always apparent, periodic testing is a good way to identify dogs that have been infected. Even dogs that receive year-round tick control products and don’t spend a lot of time outside are at risk for exposure to tick-borne diseases. Testing helps identify dogs that need treatment for one of these infections or an adjustment in the type of tick control being used.

    A vaccine is available to aid in preventing disease caused by Borrelia burgdorferi, the Lyme disease organism, but there are currently no vaccines to protect dogs from ehrlichiosis or anaplasmosis. Appropriate tick control methods combined with periodic testing may be the best ways to help protect dogs from these tick-borne infections.


    Does My Dog Really Need to Be Tested for All of These Diseases?  

    Heartworm disease has been diagnosed in every state in the United States, so veterinarians across the country routinely screen dogs for heartworm infection. However, many of the tick-borne diseases are regional, so not all dogs are at risk for exposure to the same diseases. Your veterinarian can tell you about the risk of Lyme disease, ehrlichiosis, and anaplasmosis to dogs in your area. In some cases, your veterinarian may not recommend testing for all of the diseases.  Even if you live in an area where tick-borne diseases are less common, be sure to ask your veterinarian what tick prevention measures can help protect your dog. 

    Reviewed February 2012