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Ehrlichiosis in Dogs (Vet Answer): Signs, Treatment & Causes


Apr 13, 2023
street dog infected with Ehrlichia


street dog infected with Ehrlichia
Dr. Meg Barnes Photo

The information is current and up-to-date in accordance with the latest veterinarian research.

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Ehrlichiosis is a disease spread by ticks that causes illness in people and animals. In dogs, it is also known as “tropical pancytopenia,” “tracker dog disease,” and “canine hemorrhagic fever.” The disease became prominent in the 1970s after the Vietnam War, when military dogs returned from southeast Asia. It was thought at the time that the disease originated in Vietnam. However, subsequent research discovered that it had already been around but that German Shepherds (the token military dog) can get a severe form of the disease. Since large numbers of German Shepherds were infected together at the time, the disease demanded attention in the canine sphere.


What Is Ehrlichiosis?

Ehrlichiosis is an infectious bacterial disease carried by ticks and occurs worldwide in tropical and subtropical regions. The specific type of Ehrlichia bacteria varies with the animals involved, as does the species of tick responsible for the spread of the illness.

The bacteria are skilled at destroying their host’s white blood cells, causing sequelae of events in the body that can potentially be fatal without treatment. As a result of the increase in global animal movement over the last century, we are still collecting information on ehrlichiosis, as it continues to travel to new parts of the world in countries that haven’t previously been infected.

tick on dog skin
Image Credit: chaipanya, Shutterstock

What Are the Signs of Ehrlichiosis?

There are three stages of infection: acute, subclinical, and chronic. The clinical signs depend on the stage of infection.

The acute phase occurs 1–3 weeks after a tick bite. The signs shown in the acute phase include lethargy and fatigue, inappetence, enlarged lymph nodes and spleen, fever, and sometimes neurological signs. It results in a drop in platelet count, caused by the immune system attacking and destroying the platelets. In the U.S., where the infection has been around for a while, this phase is usually mild and treatable. However, in places where there has been no prior exposure to the infection, such as Australia (which is currently experiencing its first outbreak), this phase of the illness can be severe and cause death.

Animals enter the subclinical phase if no treatment is received in the acute phase of infection, anywhere between 1 and 4 weeks after the initial infection. During this stage, dogs normally demonstrate no signs as the bacteria hide out in the spleen. The only sign that they may demonstrate is prolonged bleeding time because of their low platelet count, but otherwise, it often goes undetected. They may be able to eliminate the organism, or they may progress to the next stage of infection.

Dogs in the chronic phase of infection carry a worse prognosis, and disease at this point can be untreatable. Signs include abnormal bleeding, eye inflammation, neurological signs, increased thirst and urination from kidney disease, lameness, and swelling.

The signs to look for include:

  • Fever
  • Enlargement and swelling of the lymph nodes
  • Loss of appetite
  • Lethargy
  • Depression
  • Stiffness
  • Leg swelling
  • Coughing
  • Difficulty breathing
  • Abnormal or prolonged bleeding

What Are the Causes of Ehrlichiosis?

Ehrlichia canis (E. Canis) is caused by a bacterium that belongs to the genus Rickettsia. E. canis is the most common species involved in the disease in canines, and dogs can only be infected when they are bitten by infected ticks. The disease cannot be passed between dogs. Transmission of the disease between the tick and the dog can occur in just 3–4 hours after the tick has attached, meaning regular checks for ticks in endemic areas are crucial.

In dogs, it is mostly spread by the brown dog tick (Rhipicephalus sanguineus). This tick is present worldwide and acquires E. canis by feeding on infected dogs, which means infected dogs can introduce the disease to previously non-infected areas. This poses a problem because some dogs in certain phases of the infection show no signs of disease.

sick dog infected with Ehrlichia
Image Credit: W_NAMKET, Shutterstock

How Do I Care for a Dog With Ehrlichiosis?

If you suspect that your dog has ehrlichiosis, it is vital to take them to the veterinarian to be assessed. Your vet will perform blood tests to confirm the disease.

Ehrlichiosis can be treated with a 4-week course of an antibiotic called Doxycycline. Other supportive treatment and hospitalization may be needed depending on the severity of the clinical signs. Some dogs that are experiencing bleeding issues may need a blood transfusion. Your veterinarian will guide you to the appropriate options for your pet.

The best way to care for your dog is to ensure vigilance with tick prevention, especially in areas where the disease is known to be endemic.  Since the disease can only be spread by the bites of infected ticks, tick-prevention products will alleviate the risk of the disease altogether. These preventatives can be applied directly onto the skin or via tablets. It is simple and effective and in some cases, can be lifesaving.

divider-dog pawFrequently Asked Questions

Can Humans Catch Ehrlichiosis from Dogs?

No, humans cannot catch ehrlichiosis from dogs. They can only get it from tick bites of infected ticks. However, if your dog gets the disease, it serves as a warning that there are infected ticks in the area. E. canis can cause severe illness in the human population, but you do not have to worry about catching it from your pet.

man petting dog at the park
Image Credit: jarmoluk, Pixabay

Can Ehrlichiosis Be Cured in Dogs?

If a dog is treated in the acute or subclinical stages of infection, the prognosis tends to be quite good if treatment is sought promptly. However, if the dog progresses to the chronic phase of infection, the prognosis for recovery is poor.



If you have any concerns about your dog and whether they may be showing signs synonymous with ehrlichiosis, it is always best to be safe and to talk to your veterinarian. Ensuring that your pets are on appropriate parasite preventatives is part of being a responsible pet owner. Many diseases can be spread by ticks, ehrlichiosis being just one of them, so stay in conversation with your vet about their preventative measures, and hopefully, you will never have to deal with ehrlichiosis in your pet’s lifetime!

Featured Image Credit: W_NAMKET, Shutterstock

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