Clinical Signs/ Laboratory abnormalities

In general anaplasmosis leads to milder disease in dogs than ehrlichiosis caused by Ehrlichia canis, but with similar clinical signs. To date, no fatal case has been reported in dogs. 

After an incubation period of 10 to 14 days (for A. phagocytophilum infection) clinical signs develop, including fever (>39°C), anorexia, depression, lethargy, splenomegaly, rarely lymphadenomegaly or hepatomegaly. In some animals, reluctance to move, weakness and lameness occur as well as gastrointestinal and respiratory signs.

Hematological abnormalities in dogs with anaplasmosis include thrombocytopenia, which is the most consistent laboratory abnormality, but also anemia, lymphopenia or lymphocytosis, both neutrophilia and neutropenia as well as monocytosis and monocytopenia. Biochemical findings include hypoalbuminemia, hyperglobulinemia, elevated plasma alkaline phosphatase or hyperbilirubinemia.

Infection with A. phagocytophilum appears to be self-limiting in dogs. The extent to which the pathogen induces chronic infection is unknown. Experimentally infected dogs have developed a persistent A. phagocytophilum infection for months. Although development into a chronic disease is less likely in comparison to E. canis infection, recrudescence of anaplasmosis can occur if the animal is subsequently immunosuppressed in the months after the infection occurred.

Signs of A. platys infection include fever, anorexia, lethargy, primary hemostatic disorders as the pathogen destroys platelet cells of the host, mild anemia, and lymphadenomegaly. Bacteraemia and subsequent thrombocytopenic episodes (with platelet counts below 20,000/µl) recur at 1- to 2-week intervals. Co-infection with E. canis may lead to severe diseases.

Further information

  • Carrade DD, Foley JE, Borjesson DL, et al.: Canine granulocytic anaplasmosis: A review. J Vet Intern Med. 2009, 23, 1129–41
  • Fisher M, McGarry J: Focus on Small Animal Parasitology. 2006, Kingfisher Press Limited, London
  • Kohn B, Galke D, Beelitz P, et al.: Clinical features of canine granulocytic anaplasmosis in 18 naturally infected dogs. J Vet Intern Med. 2008, 22, 1289-95

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