Dataset for: Doxycycline treatment efficacy in dogs with naturally-occurring <i>Anaplasma phagocytophilum</i> infection

Objectives: To evaluate doxycycline treatment efficacy and post-treatment pathogen persistence in dogs naturally infected with <i>Anaplasma phagocytophilum</i> in endemic regions of the US. Methods: Symptomatic dogs in four US states (MN, WI, CT and CA) were evaluated before treatment with doxycycline and approximately 30 and 60 days post-treatment. Clinicopathological parameters, presence of co-exposures and presence of <i>A. phagocytophilum</i> DNA in whole blood and lymph node samples were evaluated and compared between <i>A. phagocytophilum</i> infected and uninfected dogs. Results: Forty-two dogs fulfilled the inclusion criteria, with 16 dogs (38%) blood PCR positive and 26 dogs (62%) blood PCR negative for <i>A. phagocytophilum</i>. At initial evaluation, the proportion of clinicopathological abnormalities was similar between <i>A. phagocytophilum</i> infected and uninfected dogs, with exception of thrombocytopenia and lymphopenia, which were statistically more prevalent among <i>A. phagocytophilum</i> infected dogs. Treatment with doxycycline resulted in resolution of all clinical abnormalities in <i>A. phagocytophilum</i> infected dogs; 4 dogs had persistent haematological abnormalities, including mild leukopenia, eosinopenia and lymphopenia. All 16 <i>A. phagocytophilum</i> infected dogs became PCR negative in blood approximately 30 and 60 days after treatment onset. Additionally, 13/13 (100%) of lymph node specimens tested post-treatment were PCR negative. Select clinicopathological abnormalities persisted in <i>A. phagocytophilum</i> uninfected dogs after treatment. Clinical Significance: The results of this study support the efficacy of doxycycline therapy for clinical treatment of dogs naturally infected with <i>A. phagocytophilum</i> in the US. This study did not find clinical, haematologic or microbiologic indicators that supported the persistence of <i>A. phagocytophilum</i> infection in naturally infected dogs following treatment with doxycycline for 28 days.