Background: Feline granulocytic anaplasmosis (FGA) is caused by Anaplasma phagocytophilum. Hypothesis/
Objectives: To describe clinicopathological abnormalities, therapy, and outcome in cats with FGA. Animals: 704 cats tested in Europe.
Methods: Retrospective screening of A. phagocytophilum PCR results was performed in cat samples submitted to the Laboklin laboratory by European veterinarians from 2022-2025. Questionnaires were sent if cats tested positive, asking for clinical signs, hematology results, treatment, and outcome.
Results: 43/704 cats (6.1%) tested positive by PCR. Thrombocytopenia (14/18, 77.8%), eosinopenia (10/17, 58.8%), and lymphopenia (8/17, 47.1%) were the most remarkable hematological findings, 2/20 cats (10.0%) each showed anemia and leukopenia. Questionnaires were available for 29/43 cats (67.4%). Outdoor access was confirmed for all cats, lethargy was present in 23/29 (79.3%), anorexia in 22/29 (75.9%), and fever > 39.5 °C in 18/29 cats (62.0%). 20/21 cats (95.2%) were treated with doxycycline, and one (4.8%) with enrofloxacin. Uncomplicated disease was reported in 19/21 cats (90.5%). One cat with no underlying diseases was treated with doxycycline for 10 days only due to fast recovery and showed another positive PCR result 2 months later. Another cat was under doxycycline for 5 days and clinical signs re-occurred. It was treated for another 14 days with clinical recovery. Conclusions and Clinical Importance: FGA should be considered in cats with outdoor access and thrombocytopenia in endemic areas. Fever was detected in only 62% of the cats with FGA. Although infected cats usually respond rapidly to doxycycline, treatment for 14 days and PCR monitoring after finishing treatment are recommended.
