Canine anaplasmosis
Also called Cyclic thrombocytopenia (Anaplasma platys)
A tick-borne infection of dogs that is often silent. When it causes illness, there is fever, joint pain or bleeding tendencies, and the platelet count in the blood falls.
Cause and spread
- Cause
- The bacteria Anaplasma phagocytophilum (white cells) and Anaplasma platys (platelets).
- How it spreads
- By ticks: Anaplasma platys by the brown dog tick, and Anaplasma phagocytophilum by Ixodes ticks. It can also pass through blood transfusion.
- People
- Anaplasma phagocytophilum can infect people; take care to remove ticks promptly and safely.
Signs to watch for
- Usually no signs
- Fever, swollen lymph nodes and spleen
- Pinpoint bleeds and bruising
- Lameness (with Anaplasma phagocytophilum)
- A low platelet count that rises and falls in cycles of 1 to 2 weeks (Anaplasma platys)
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
A blood count shows low platelets, usually 1 to 2 weeks after infection. Antibody tests may be negative in the first week, so they are repeated 2 to 4 weeks later. PCR on blood can find infection soon after it starts.
- Usually the first testComplete Blood Count (CBC)Shows a low platelet count.
- Confirms the diseaseAnaplasma platys PCRDetects Anaplasma platys.
- Confirms the diseaseAnaplasma phagocytophilum PCRDetects Anaplasma phagocytophilum.
- Supports the diagnosisBlood Smear ExaminationCan show inclusions in blood cells.
Prevention and control
- Control tick exposure: tick-control products, avoid tick-infested areas and check dogs after walks
- Remove ticks carefully to avoid exposing people
Where this information comes from
- Anaplasmosis in Dogs · Merck Veterinary Manual
- Ehrlichiosis and Anaplasmosis (factsheet) · Center for Food Security and Public Health, Iowa State University
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.