Ehrlichia in Dogs

​What is Ehrlichia?

Ehrlichia is a bacterial disease spread via tick bites. Nearly 25% of dogs in Taney County test positive for Ehrlichia, and it is one of the most common infectious diseases in the US. Ehrlichia cycles between dogs, ticks, white-tailed deer, and humans. Our clinic and the Companion Animal Parasite Council recommend yearly screening to identify dogs at risk of disease.

ehrlichia in dogs

Nearly 1 in 4 dogs tested for Ehrlichiosis test positive in Taney County, Missouri. Image taken from

Why has my dog tested positive on the annual 4dx screening test?

A positive test means your dog has been exposed to ticks and at least one infection they carry. Some additional lab work (blood cell counts, organ chemistry panel, and urinalysis) are needed to help determine if this infection is causing active disease, and these tests should be monitored annually for the rest of your dog’s life. It can take 10+ years to develop disease after the initial tick bite and infection.

What happens after a dog is infected with Ehrlichia from an infected tick?

The “subclinical” phase is the stage where infection is present but no symptoms or blood work changes are observed. Subclinical cases can become symptomatic cases, but the length of time between exposure and development of symptoms is impossible to predict. In the absence of treatment, infection can persist for the life of the dog. Certain strains of Ehrlichia appear to be more self-limiting, and occasionally dogs can clear these infections without treatment.

The classic Ehrlichia symptoms are stiffness, swollen joints, or reluctance to move, but a variety of symptoms such as fever, reduced activity, “seeming old”, depression, anorexia, weight loss, enlarged lymph nodes, or bleeding disorders may be evident. Occasionally dogs may present with neurologic disease, vomiting, diarrhea, or eye lesions.

Clinical Ehrlichia infections can cause changes on routine screening blood work such as low platelet or blood cell counts or evidence of organ damage. Recent studies have shown dogs that have tested positive for Ehrlichia exposure have a 112% increased risk of developing chronic kidney disease.

*Although Ehrlichia has been reported to cause disease in cats, it is poorly understood at this time. Fever, lethargy, anorexia, weight loss, bruising, joint pain, respiratory distress, vomiting, and diarrhea have all been described as symptoms of feline Ehrlichia infections.

What is the recommended protocol following a positive Ehrlichia test?

The next step is screening baseline lab work (Complete Blood Counts, organ chemistry panel, and urinalysis) to check for common complications. If symptoms are noted on blood work, physical exam, or at home, then treatment is indicated. For a first-time positive test result, we generally recommend treatment as we view this as an opportunity to potentially clear the infection before disease occurs.

For subsequent positive annual screens, treatment is not indicated if no other symptoms or lab work abnormalities consistent with an active infection are found. Lab work is recommended annually to watch for development of disease—this is recommended for the rest of your dog’s life. You should also monitor at home closely for any changes or possible symptoms.

How can we treat an Ehrlichia in Dogs?

Ehrlichia infections often respond to treatment with the antibiotic doxycycline for 28 days; however, this will fail to clear the infection in some dogs. Dogs with severe infections may require hospitalization and aggressive care. Long-lasting immunity does not appear to develop, and reinfection is very common in this area due to continued exposure through more tick bites.

How can we prevent Ehrlichia in Dogs?

You can reduce risk of exposure to tick diseases with year-round tick control, avoiding areas with ticks, and frequent tick-checks with prompt removal following potential tick exposure. Although there have been exciting developments in safety and effectiveness of parasite preventatives in recent years, at this time we do not yet have any products available that have been proven to kill ticks fast enough to completely prevent Ehrlichia infection.

Modifying the environment around the home through basic measures like keeping shrubbery and grass closely clipped can reduce tick populations. There is no vaccination available to prevent Ehrlichia infections.

Are human family members at risk?

People can be infected with certain strains of Ehrlichia the same way that dogs get exposed–through the bite of an infected tick. An infected pet is not considered a direct source of infection to people. Prevention of human infection relies on preventing tick bites.

Routine use of high-quality parasite preventatives helps limit infestations and thus reduces the risk of family pets from bringing ticks into the home. People should also take basic precautions when in tick-infested areas.