What is Ehrlichiosis?

Ehrlichiosis is a bacteria transmitted by ticks to dogs.  The bacteria infects and lives in the white blood cells of the host which can be human, pets or wild animals.  It is usually transmitted to dogs by the Brown Dog Tick.  Ehrlichiosis occurs worldwide and can infect any dog, although some breeds, such as the German Shepherd, seem more prone to serious chronic infections.  It can occur concurrently with Biliary, or Babesiosis which is the better known and more common form of tick fever.

Signs and Symptoms of Ehrlichiosis

The symptoms and severity can vary according to the type of Ehrlichia bacteria involved and the immune response of the individual dog.  The infection follows 3 phases.

3 Phases of Ehrlichiosis Infection

1.  Acute Phase

This occurs in the first 1 – 3 weeks after infection.  Symptoms can include lethargy, depression, fever and lack of appetite and weight loss.  This is very non-specific and dogs can sometimes spontaneously recover while others will enter the next “silent” or sub-clinical phase.

2.  Sub-clinical Phase

In this phase there may be no apparent symptoms.  This phase of Ehrlichiosis can sometimes last for months or even years.  The bacteria lodges in the spleen and bone marrow.  Cell counts can change as the parasite is slowly dividing and stimulating the immune system of the dog.  Some dogs will then progress to the chronic phase.

3.  Chronic Phase

When the bone marrow is damaged beyond repair and runs out of stores of stem cells to produce new red, white and clotting blood cells, the dog will start to show the clinical signs of these deficiencies and usually become severely ill.

The most common symptoms in this phase would be bleeding or discharge from the nose or blood spots under the skin (looking like spots or patches of bruising), chronic, recurring infections, particularly respiratory, muscle wasting due to kidney failure, and severe weakness due to anaemia (lack of red blood cells).  There may also be enlarged lymph nodes and spleen, pain and stiffness, vomiting and diarrhoea, inflammation of the eye and possible neurological symptoms.


Diagnosis of Ehrlichiosis is not simple.  It is usually done with blood tests and on the overall clinical presentation of the dog.  The Ehrlichia organisims very seldom show up in a blood smear, but if they do a diagnosis can be confirmed.  Blood can be tested for Ehrlichia antibodies, and can also show changes in cell count and type.  A combination of tests is usually used.

Diagnosis is further complicated by the fact that the dog may be infected with more than one tick borne disease at a time.


Fortunately Ehrlichiosis responds well to antibiotic treatment which can cure almost all acute and most sub-clinical cases. Although several weeks of treatment is necessary improvement in symptoms is usually very quick. In severe cases where blood cell counts are very low blood transfusions may be needed.

The best solution for Ehrlichiosis is to prevent it!  Use regular parasitic preventative measures such as dips, “spot on” treatments, flea and tick collars etc.  Also try and avoid taking your dog into tick infested areas such as long grass, open fields, or woods during peak tick season.  And check your dog daily for ticks.

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