Ehrlichiosis in Dogs: What It Is, Symptoms, and Treatment

Ehrlichiosis in dogs, caused by ticks, has become a much more widespread and common disease that can have debilitating effects—some even long-lasting.  It’s a challenging disease to diagnose and treat, but fortunately, it can be prevented.   

Read on to learn about how the disease is managed and a few action steps you can take to keep your pup safe and healthy!  

What Is Ehrlichiosis in Dogs?

Ehrlichiosis in dogs is a tick-borne disease caused by the infectious bacteria Ehrlichia.  

There are many species of Ehrlichia, but the two most common species responsible for ehrlichiosis in dogs in the United States are E. canis and E. ewingii. This bacterium attacks white blood cells in dogs. 

Less attention is paid to E. ewingii infection because it’s typically not as serious as E. canis infections. Most dogs with E. ewingii are only mildly ill (fever, swollen joints) or may not even show signs of illness.  

Geographically, ehrlichiosis in dogs is most often reported in the southeastern and south-central United States. The highest number of cases occurred in the following states:

• Arkansas

• Louisiana

• Oklahoma

• Tennessee

• Texas  

Ehrlichiosis can’t be spread from dog to dog, but if multiple pets were exposed to the same area of ticks, consult your vet about testing and/or treating all dogs in your household. 

Humans can’t get E. canis, but can become infected with other types of ehrlichiosis, including E. ewingii.  

However, ehrlichiosis is not zoonotic—meaning humans can’t get the disease directly from dogs. However, they get the disease from tick bites.  

If you think you have been exposed to ehrlichiosis, seek medical attention immediately.   

Symptoms of Ehrlichiosis in Dogs

Symptoms of ehrlichiosis in dogs can be divided into three phases: acute, subclinical, and chronic. 

The acute phase (early disease) occurs one to three weeks after a dog is bitten by an infected tick. During this time, the E. canis bacteria is reproducing and attaching to white blood cells. Signs typically seen in the acute phase are: 

• Fever  

• Lethargy 

• Depression  

• Anorexia 

• Weight loss 

• Enlarged lymph nodes  

• Lameness 

• Vomiting 

• Diarrhea 

• Cough  

• Abnormal bruising and bleeding 

• Neurologic signs, such as loss of balance or stumbling 

If treated in the acute phase, most dogs will clear the infection completely and return to normal. Dogs that do not receive treatment will likely progress to the subclinical phase in weeks one to four. 

In the subclinical phase, dogs will still be infected but show no signs of disease. The bacteria hide in the spleen where it can remain for months or years. The dog will have no symptoms but may have changes in their blood work. Not all dogs will progress from the subclinical to the chronic phase—some dogs may clear the disease on their own. 

Dogs that were unable to eliminate the bacteria and become sick again are in the chronic phase (long-term disease).   

Chronic phase symptoms include: 

• Abnormal bleeding, which can lead to anemia. 

• Inflammation in the eyes (uveitis), bleeding in the eye (hyphema), or blindness 

• Neurologic signs, such as loss of balance or stumbling 

• Increased urinating (polyuria) and increased drinking (polydipsia) from damage to kidneys 

• Lameness 

• Swollen limbs 

Dogs in the chronic phase have a worse prognosis. This phase can become fatal, though this is uncommon. 

Causes of Ehrlichiosis in Dogs

Ehrlichiosis in dogs caused by E. canis is transmitted by the brown dog tick.  

Ehrlichiosis in dogs caused by E. ewingii is transmitted by the Lone Star tick. 

Disease transmission can occur in as little as three to six hours after the tick attaches—because of this, immediate tick removal is very important. 

How Veterinarians Diagnose Ehrlichiosis in Dogs

To diagnose ehrlichiosis in dogs, your vet will start with a physical exam to look for symptoms. They will also ask you of any recent travel or tick exposure. 

Your vet may also recommend a variety of tests including a urinalysis and blood work.  

Other tests—which often require samples to be sent to a laboratory—include an IFA (indirect fluorescent antibody) or PCR (polymerase chain reaction). 

Treatment of Ehrlichiosis in Dogs

Ehrlichiosis in dogs is typically treated with a 28- to 30-day course of antibiotics (typically doxycycline).  

Most dogs in the acute or subclinical phases won’t need to be hospitalized. They can be managed at home with supportive care, such as pain medications (like gabapentin or tramadol) and appetite stimulants like (Entyce or mirtazapine). 

Dogs with chronic ehrlichiosis may require hospitalization for more intensive supportive care—this includes blood transfusions, steroids, intravenous (IV) fluids, and nutritional support. 

In many cases, dogs with ehrlichiosis will also be infected with other tick-borne diseases such as anaplasma or Lyme disease, which may complicate diagnosis and treatment.  

Your veterinarian will create a treatment plan to your dog’s specific needs. 

Recovery and Management of Ehrlichiosis in Dogs

Dogs with acute or subclinical ehrlichiosis from E. canis tend to improve within one to two days of starting therapy and have an excellent prognosis for recovery.  

Each day should be marked with progress in your dog’s symptoms and keeping them comfortable with: 

• A high-quality dog bed 

• Comfortable dog blankets (especially if their joints hurt)  

• A high-quality diet 

• Easy access to water  

Follow all your veterinarian’s directions in terms of medication, diet, and exercise.   

Limiting your dog’s exercise while they recover is important to prevent excessive bruising (from trauma or rough play) and will help lessen pain from stiff or swollen limbs.  

Dogs with E. ewingii infection tend to recover quickly after antibiotics have started. Once recovered, dogs can still have antibodies in their blood for several years but are cured of the infection. 

Unfortunately, dogs with chronic E. canis infection have a guarded prognosis—meaning that they may or may not get better with treatment.   

Dogs with serious infections or complications may pass away. A veterinarian may recommend humane euthanasia for pets affected with significant quality of life concerns or life-long complications. 

Dogs who survive ehrlichiosis can become re-infected later in life as immunity is not lifelong—which is why prevention is of utmost importance!  

How To Prevent Ehrlichiosis in Dogs

While ehrlichiosis in dogs is preventable, there currently is no vaccine against this disease.  

Fortunately, most tick bites can be prevented through monthly flea and tick preventatives.

There are plenty of options available, including topical, tablet, and chewable medications like Simparica, Bravecto, and NexGard. 

Your vet can help you find the best option for your pet. 

If you live near wooded areas where ticks may dwell, keep your dog away from these areas. 

When your dog comes back from any outdoor adventure, inspect them for any ticks or fleas and remove them safely. Early removal of ticks is the best defense against the spread of any infection.