Rickettsial Infection in Dogs

Canine ehrlichiosis is an acute to chronic infectious disease that is transmitted to dogs by ticks. Ehrlichiosis can affect multiple organ systems and present with a variety of clinical signs. It is caused by one of several rickettsial (a kind of bacteria) organisms that belong to the genus, Ehrlichia. Ehrlichia canis (E. canis) is the primary causative agent in dogs.

Ehrlichia are a type of bacteria that infect and live within the white blood cells of their hosts. Different types of Ehrlichia live in different types of white blood cells. Hosts can be human, pet, or wild animals. Ehrlichia are spread from host to host by tick bites and their intracellular location makes them difficult to remove as most antibiotics do not penetrate to the inside of cells.

Ehrlichiosis is a tick-borne disease which is more prevailent in warm areas. Chronic and severe forms of this disease are more representative in Doberman pinschers and German shepherds.

There are three phases of stages of Ehrlichiosis, acute, subclinical and chronic stage. The acute phase occurs within the first few weeks of being infected and is rarely fatal. Recovery can occur, or the dog can enter a "subclinical phase" which can last for years, where there are no symptoms. Some dogs, but not all, eventually progress to the chronic phase, where very severe illness can develop. However, in practice is is difficult to distinguish these phases.

The three stages and corresponding symptoms are:

Acute stage:

Symptoms present around 1-3 weeks after bite from infected tick

Enlarged lymph nodes




Lack of appetite

Difficult respiration

Limb edema

Subclinical stage:

Bacteria may be present for months or years without clinical symptoms

Chronic Stage:

Abnormal bleeding

Nose bleed

Severe weight loss


Trouble breathing due to inflammation of the lungs

Joint inflammation and pain

Seizures in some animals

Lack of coordination

Head tilt

Eye pain


Kidney failure


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