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Ask the Vet: What is the tick-borne disease Ehrlichiosis?

Do you worry about your dogs and ticks? As it turns out, Lyme disease is not the only tick-borne illness we need to be concerned about (for our pets and ourselves).

Minnie smiles

Courtesy Fido Fetch Photography

A while back, former foster dog Minnie’s momma informed me that the sweet husky mix had been diagnosed with something called Ehrlichia canis, a tick-related problem neither of us had heard of before. Figuring that many Wayward Dogs readers also don’t know much about Ehrlichia canis and the disease it causes. So, I asked my vet, who provided the following exhaustive report.

Ehrlichiosis is a tick-borne disease of dogs caused by the intracellular organism Ehrlichia canis.  Both the Brown Dog Tick and the American Dog Tick can pass the organism into the blood when they bite a dog.  It requires 24-48 hours of feeding for the organism to pass from the tick to the dog.  The organism enters white blood cells where they multiply and disseminate throughout the dog.  Dogs with the disease caused by the infection of E. canis commonly present with fever, lethargy, anorexia, acute lameness or polyarthritis, enlarged lymph nodes, or weight loss.

The inflammatory process caused by the infection can also result in thrombocytopenia (low platelet production), which results in petechial hemorrhages, nose bleeds, and other bleeding abnormalities.  Occasionally dogs may present with neurologic disease, vomiting or diarrhea, or ocular lesions.

Cats and humans can also be infected by E. canis from the bite of an infected tick.

I, Gary Alpert [GFDL (, CC-BY-SA-3.0 ( or CC-BY-2.5 (], via Wikimedia Commons

Dog tick, image courtesy Gary Albert via Wiki Creative Commons.

In cats the disease is similar to dogs.  In humans, infection by E. canis is not as common as other tick-borne diseases and causes flu-like symptoms which may progress to varying symptoms caused by immune dysregulation.

Veterinarians have been diagnosing E. canis infection increasingly due to the addition of the 4 common tick disease antibody tests to the IDEXX Heatworm Snap Test in recent years.  The increasing incidence of positive tick disease tests at Aid Animal Hospital is similar to other clinics in areas of the country where the disease-carrying ticks are commonly found.

Some dogs testing positive in our practice are showing symptoms at the time of diagnosis, some are without symptoms and are found to be positive on routine screening.  Because of the different symptoms caused by E. canis infection based on whether it is an acute, sub-clinical, or chronic infection, it is almost impossible to diagnose a pet based on symptoms alone.

husky mix with legs crossed

Minnie thinks ticks are dumb.

Any pet owner who removes an attached tick from a pet should watch for signs of illness such as fever, lethargy, anorexia or acute lameness.

The treatment for E. canis is usually doxycycline, for 4-6 weeks, but may be longer.  Treatment for the disease caused by E. canis is based on the symptoms exhibited by the dog and can include intravenous fluids, anti-inflammatories, antibiotics, blood transfusions, or other treatments specific to the organs affected.

Other tick-borne disease include: Rocky Mountain Spotted Fever, Lyme Disease, Q-Fever, and infections caused by other Ehrlichia species such as Human Granulocytic and Human Monocytic Ehrlichiosis.

The best way to prevent infection by E. canis is by protecting your pet from ticks using effective flea and tick products regularly.

Always inspect your pet’s hair and skin after being in areas potentially infested by ticks.  Frequent brushing and combing can expose ticks hiding in areas like face, ears, underarms, groin, and around the peri-anal area.  If an embedded tick is found, use gloves and tweezers to remove the body and head of the tick, followed by thorough handwashing.  Because tick activity can occur year round due to mild weather conditions, pets should be maintained on tick control products year round.


1)      Companion Animal Parasite Council-

2)      Wikipedia– Ehrlichiosis, canine and human infection

 Thanks to Dr. Smith at Aid Animal Hospital in Kansas City for preparing this report.

Minnie the husky mix standing in water

Minnie’s mama says she’s doing fine now.

Have the ticks been bad where you live this year? Have you ever heard of Ehrlichiosis?

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