The 4DX Test

You arrive at the clinic for your dog’s heartworm test and the staff refers to the blood test as a 4DX. What does that mean exactly? A 4DX test evaluates your dog’s blood for 4 specific diseases – heartworm, Anaplasma, exposure to Lyme bacteria and Erlichia canis.

This article will hopefully help you understand what each of these diseases are and how do they affect your dog.

Heartworm Disease

Heartworm is carried by mosquitoes and is transmitted when an infected mosquito bites your dog. Heartworm disease is very dangerous for your dog and the worms can cause serious cardiovascular disease as well as pulmonary disease. We test dogs prior to starting heartworm prevention to ensure there is no active infection present before starting any of the preventative medications.

Anaplasma Phagocytophilum

Is a disease that is transmitted by deer ticks. Symptoms include fever, lethargy, joint stiffness and signs of prolonged bleeding. A positive test for Anaplasma means that your dog has been exposed to the disease but does not mean the disease is active. If the test returns positive one of our veterinarians will discuss with you the recommendations for care and treatment as needed.

Lyme Disease

Lyme disease is caused by the bacteria Borrelia burgdorferi, this bacterium is transmitted by a deer tick bite. Symptoms of the disease typically include joint stiffness, fever, inappetence, and in some cases, it can cause renal failure. The 4DX test shows us that your dog has been bitten by a deer tick and exposed to the bacteria. A positive test does not mean your dog has an active infection but has the risk of falling ill from the disease. If the test returns positive one of our veterinarians will discuss with you the treatment options and recommendations regarding care of your dog. If the test is positive we will also run a urinalysis to rule out renal disease brought on by the disease.

Erlichia canis

Is another tick-borne disease and can cause a variety of symptoms. It is an infection of the white blood cells and can affect bone marrow function. Symptoms can include, depression, lethargy, inappetence, nasal discharge, signs of bruising, lameness and joint pain. If the test returns positive one of our veterinarians will discuss with you treatment options and recommendations regarding care of your dog.

Written by The Fairmont Animal Hospital Team


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Last updated: April 1, 2021

Dear Clients,

With recent changes to restrictions on businesses, we have made some important updates to our operating policies.


This includes vaccines, wellness exams, blood work, heartworm testing, spays and neuters, dental services, and more!



If you wish to connect with a veterinarian via message, phone or video, visit our website and follow the "Online Consultation" link. You will be connected to an on-call veterinarian that may be located at a different hospital.


Have you welcomed a new furry family member to your home? We’d love to meet them! Visit our Must Know New Pet Owner Information page for useful resources and helpful recommendations for new pet owners.


We are OPEN with the following hours:

Monday - Thursday: 8:00 am - 7:00 pm
Friday: 8:00 am - 6:00 pm
Saturday: 8:00 am - 1:00 pm
Sunday: CLOSED


Thank you for your patience and understanding and we look forward to seeing you and your furry family members again!

- Your dedicated team at Fairmont Animal Hospital