Ehrlichia in Dogs

Ehrlichia is a type of bacteria and a tick borne disease in dogs and other animals, including humans.  Ehrlichia causes ehrlichiosis in dogs.  It is primarily transmitted by the brown dog tick.  It can also be transmitted from an infected donor dog to a blood recipient dog.

Ehrlichia bacteria infect the white blood cells.  The severity of the illness and the specific signs and symptoms depend on the particular species of Ehrlichia that infects the dog.  Ehrlichia canis causes the most severe symptoms.

Ehrlichia causes illness in stages.  The acute stage occurs within a few weeks of being infected and is rarely fatal.  Some dogs enter a subclinical phase that can last years without any symptoms.  Finally, some dogs enter the chronic phase where very serious illnesses may result from the infection.  In practice, it is difficult to differentiate the acute and chronic phases.

Ehrlichia can cause the following symptoms in dogs:  fever, lethargy, loss of appetitie, weight loss, abnormal bleeding such as nosebleeds or bruising, enlarged lymph nodes, enlarged spleen, pain and stiffness, coughing, discharge from the eyes or nose, vomiting and diarrhea, inflammation of the eye, and neurological symptoms such as incoordination, depression, and paralysis.  Other organs can become involved in the chronic form, especially kidney disease.

Ehrlichiosis can be difficult to definitively diagnose.  Blood tests may show low platelets and sometimes a decrease of red or white cells.  Protein levels in the blood may change.  Blood smears can be examined for Ehrlichia organisms, but they do not always show up in a blood smear.  However, if they are found, the dog definitely has ehrlichiosis.  Generally, a combination of the dog’s history, symptoms, and the results of lab tests are used to diagnose ehrlichiosis.

Because dogs that are infected with Ehrlichia may also be infected with Lyme disease or Rocky Mountain Spotted Fever, it can increase the difficulty of diagnosis and treatment.

Ehrlichiosis usually responds well to the antibiotic doxycycline.  Symptoms improve quickly, but several weeks of antibiotics are necessary to completely eradicate the disease.  If blood cell counts or platelets are very low, blood transfusions may be needed.

To prevent Ehrlichiosis, it is best to prevent dogs from being around the ticks that carry Ehrlichia.  This is not always practical, particularly with hunting dogs that range widely.  You should check your dogs daily for ticks and remove them as soon as possible.  It appears ticks must be attached for at least 24-48 hours to spread Ehrlichia.  This is especially important during the peak of tick season, but ticks can be active any time the temperature is above 32 degrees, so winter infestation is possible.

The most practical prevention for dogs is the use of monthly flea and tick preventives.  These include topical preventatives such as Frontline® and preventatives that are given orally with the dog’s heartworm medicine.  If ticks are a serious problem in your area, you may also consider treating the yard and kennel area.