Ehrlichiosis / Ehrlichia canis (dog)

Pathogen / Biology

The causative agent of canine monocytic ehrlichiosis is Ehrlichia canis, a Gram-negative, obligately intracellular bacterium belonging to the family Anaplasmataceae (order Rickettsiales). The pathogen infects monocytes and multiplies within them in characteristic inclusion bodies (morulae). Among related pathogens, Ehrlichia ewingii causes a granulocytic form of the disease, which, however, exhibits a different pattern of distribution.

Transmission / Epidemiology

Ehrlichia canis is transmitted primarily by the brown dog tick (Rhipicephalus sanguineus). Ehrlichiosis is found almost worldwide and is endemic in Mediterranean and tropical to subtropical regions; in Central Europe, it occurs primarily in imported dogs or following stays abroad. The infection is frequently associated with other vector-borne pathogens such as Anaplasma, Babesia, or Leishmania.

Course & Symptoms

The disease typically progresses in three phases. In the acute phase, a few weeks after infection, nonspecific signs such as fever, lethargy, loss of appetite, swollen lymph nodes and spleen, and a decrease in blood platelets (thrombocytopenia) appear. This is followed by a subclinical phase without external symptoms, during which the pathogen can persist for months to years. If the pathogen is not eliminated, a chronic phase may develop, characterized by a tendency to bleed, weight loss, ocular changes, and bone marrow suppression; this phase is more common in German Shepherds and is significantly more difficult to treat.

Diagnostic Relevance

The clinical and laboratory findings are nonspecific. Since antibodies may not yet be present in the early acute phase, a negative result during this time window should be interpreted with caution; in the subclinical and chronic phases, however, antibody detection is well-suited to indicate exposure to the pathogen. Due to the shared vectors and overlapping clinical presentation, it is advisable to simultaneously test for other tick-borne pathogens.

Rapid Test Component

The Fassisi® EhrCanis test detects antibodies against Ehrlichia canis in serum, plasma, or whole blood. In the CanVecto 3, CanVecto 4, and CanVecto Trio combination tests, antibodies against Ehrlichia canis are detected alongside other vector-borne pathogens, which facilitates the evaluation of multiple pathogens from a single sample in cases of suspected infection and a corresponding travel history.

Sources for the information provided.