This spring, dog owners may have noticed that we are using a different heartworm test this year. The test is called a 4DX and it detects antibodies to heartworm plus the tick borne diseases Lyme, Ehrlichia, and Anaplasma.
It can be scary and confusing to get positive results, so I’d like to take a few posts to go over what positive results on these tests mean and what we recommend doing about them. This post will focus on Ehrlichia.
First: Don’t panic! A positive Ehrlichia test does not necessarily mean your dog has an active infection right now requiring treatment. It means that at some point your dog has been exposed to the Ehrlichia organism and produced antibodies. The test does not tell us if the exposure was recent or in the past or whether your dog needs treatment.
How do we tell the difference? We use a combination of assessing whether your dog is currently showing symptoms and additional blood testing. A small percentage of dogs exposed to Ehrlichia will become clinically sick; the rest may successfully fight the bacteria off and show no or very mild symptoms. Symptoms of Ehrlichia include lethargy, high fever, loss of appetite, lameness/stiffness, and enlarged lymph nodes. Some dogs may appear to recover from their symptoms but enter a chronic state of disease in which the organism damages blood cells with several potential serious complications.
If most dogs don’t get sick from exposure to Erlichia and a positive test doesn’t necessarily mean a dog needs treatment, why do we do it or care about a positive test? There are a few reasons:
- Ehrlichia can progress to a chronic phase where dogs don’t appear sick but the organism is damaging blood cells and can trigger serious inflammation in the eyes, brain, or kidneys.
- Evidence of exposure to Ehrlichia tells us whether preventative measures such as tick control products have been effective.
- Your dog’s exposure to Ehrlichia reminds you that you need to be careful, too! Since most of us are spending time in the same places our dogs are, they can be an important sentinel for our own risks of exposure to tick-borne diseases.
Soooo… after all of that, what do we actually DO if a dog tests positive?
For a dog with a positive test but no current symptoms of Ehrlichia, we recommend a test called a complete blood count or CBC, which looks at the numbers of red and white blood cells and cells that clot the blood called platelets. If the CBC is normal, no further action is needed. If any of those cells are abnormally low, we treat your dog with an antibiotic called doxycycline for 30 days and then recheck the CBC. Once the CBC is normal, no further action is needed. Also ensure diligent tick control measures moving forward. There is currently no vaccine available for Ehrlichia.
For a dog with symptoms of Ehrlichia and a positive test, we treat with doxycycline for 30 days plus pain relievers as needed. Typically we see an improvement in symptoms within 1-3 days once starting treatment. We also recommend monitoring CBCs as noted above.
I hope this post has demystified a positive Ehrlichia test and explained why we have added them to your dog’s yearly heartworm test. We want you to enjoy the great outdoors with your dogs, but keep them safe, too! As always, if you have additional questions please feel free to speak to one of our doctors.
Karen Christopherson DVM CVA