Anaplasma spp

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Inclusions (arrows) within 2 neutrophils on a blood smear from a dog with A. phagocytophilum infection. Modified Wright’s stain[1]

Anaplasma spp are a Gram-negative, tick-borne zoonotic hemotropic parasitic proteobacteria of dogs in North and South America, predominantly in the Central and Eastern regions of the continent[2].

Transmission is commonly observed via Ixodes scapularis hard ticks in endemic regions[3].

Species which are pathogenic to dogs include:

  • Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila)[4][5]
  • Anaplasma bovis
  • Anaplasma platys[6]

Co-infections with other hemoplasmas such as Borrelia spp and Ehrlichia spp is common[7]. In many routine surveys of wild canids, Dirofilaria spp is also detected on routine blood sampling[8].

Clinical signs associated with anaplasmosis include lethargy, anorexia, fever arthropathy, anemia, and gastrointestinal signs such as abdominal pain, diarrhea and vomiting. Lymphadenopathy, splenomegaly, neurologic dysfunction, retinal detachment and epistaxis have also been reported[9]. Many subclinical infections without clinical signs are also possible[10].

Hematological changes include thrombocytopenia, morulae in neutrophils, anemia, leukopenia, eosinopenia, lymphopenia, and monocytosis.

Diagnosis is by microscopic identification of parasites on blood smears, ELISA[11] or PCR assays[12].

Treatment involves use of doxycycline (5 mg/kg orally every 12 hours) or imidocarb (single injection at 1.5 mg/kg SC).

Prevention is critical to eradication of tick-borne diseases in endemic regions, and control of tick populations on dogs by preventive topical fipronil, amitraz or other acaricides is important.


  1. Cockwill KR et al (2009) Granulocytic anaplasmosis in three dogs from Saskatoon, Saskatchewan. Can Vet J 50(8):835-840
  2. Bowman D et al (2009) Prevalence and geographic distribution of Dirofilaria immitis, Borrelia burgdorferi, Ehrlichia canis, and Anaplasma phagocytophilum in dogs in the United States: Results of a national clinic-based serological survey. Vet Parasit 160:138–148
  3. Ogden NH et al (2006) Climate change and the potential range expansion of the Lyme disease vector Ixodes scapularis in Canada. Intl J Parasitol 36:63–70
  4. Woldehiwet Z (2010) The natural history of Anaplasma phagocytophilum. Vet Parasitol 167(2-4):108-122
  5. Barth C et al (2012) Prevalence of antibodies against Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum and their clinical relevance in dogs in Munich, Germany. Berl Munch Tierarztl Wochenschr 125(7-8):337-344
  6. Bowman DD (2011) Introduction to the alpha-proteobacteria: Wolbachia and Bartonella, Rickettsia, Brucella, Ehrlichia, and Anaplasma. Top Companion Anim Med 26(4):173-177
  7. Mircean V et al (2012) Seroprevalence and geographic distribution of Dirofilaria immitis and tick-borne infections (Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, and Ehrlichia canis) in dogs from Romania. Vector Borne Zoonotic Dis 12(7):595-604
  8. Villeneuve A et al (2011) Seroprevalence of Borrelia burgdorferi, Anaplasma phagocytophilum, Ehrlichia canis, and Dirofilaria immitis among dogs in Canada. Can Vet J 52(5):527-530
  9. Carrade DD et al (2009) Canine granulocytic anaplasmosis: a review. J Vet Intern Med 23:1129–1141
  10. Kohn B et al (2008) Clinical features of Canine Granulocytic Anaplasmosis in 18 naturally infected dogs. J Vet Intern Med 22:1289–1295
  11. Eberts MD et al (2011) Typical and atypical manifestations of Anaplasma phagocytophilum infection in dogs. J Am Anim Hosp Assoc 47(6):e86-94
  12. Rotondano TE et al (2012) An assessment of whole blood and fractions by nested PCR as a DNA source for diagnosing canine ehrlichiosis and anaplasmosis. Scientific World Journal 2012:605743