Canine Anaplasmosis: Symptoms, Transmission Routes, and Treatment & Prevention Guide

Infection/ParasitesDiseasesMeongsiljang Veterinary Advisory Board

Canine anaplasmosis is a bacterial infection transmitted by ticks, characterized by symptoms such as high fever, lethargy, and decreased platelet count. When detected early, it can typically be fully cured with antibiotics.

What is Canine Anaplasmosis?

A puppy being tested for tick infection at a veterinary clinic

Canine anaplasmosis is a bacterial infection caused by Anaplasma spp. entering the body through tick bites. The bacteria directly parasitize white blood cells and platelets, attacking the hematologic and immune systems. While most cases can be fully cured with antibiotics if detected early, leaving the condition untreated can lead to serious bleeding risks. If your dog develops abnormal symptoms such as high fever and lethargy within one to two weeks after a tick bite, seek veterinary care immediately.

How is it Transmitted? — Tick Transmission Routes

Anaplasma bacteria are primarily transmitted by two types of ticks.

Anaplasma phagocytophilum: This is transmitted by ticks of the Ixodes genus (such as the deer tick). The risk of exposure is high when walking in forests or grassy areas. The longer the tick remains attached to the skin, the greater the risk of bacterial transmission, so it is crucial to remove any tick found immediately.

Anaplasma platys: This is transmitted by the brown dog tick (Rhipicephalus sanguineus). This bacterium infects platelets, causing periodic decreases in platelet count (cyclic thrombocytopenia in dogs), which increases the risk of bleeding.

Ticks transmit the bacteria not through their eggs, but by passing the infection to the next stage of their development. Therefore, be especially cautious to avoid exposure in outdoor environments where tick activity is high during the spring and autumn.

Key Symptom Checklist — Suspect if These Symptoms Appear

Within 1–2 weeks after infection, the following symptoms may appear:

High fever (39.5°C or higher): This is typically the first and most characteristic sign.

Severe lethargy: Your pet will show a noticeable decrease in activity compared to usual.

Loss of appetite: They may eat very little or refuse food entirely.

Joint pain and limping: Your pet may be reluctant to move their legs or stand up.

Vomiting and diarrhea: Gastrointestinal symptoms may also occur.

Signs of bleeding: If you notice nosebleeds, bleeding gums, or skin bruising, it may indicate a drop in platelet count.

Seek Emergency Veterinary Care Immediately if These Symptoms Occur

If your pet suddenly develops a nosebleed, bleeding gums, or skin bruising, is too weak to stand due to severe lethargy, or experiences vomiting and diarrhea lasting more than 24 hours, you should seek emergency veterinary care immediately. A rapid drop in platelet count can significantly increase the risk of internal bleeding.

How is it Diagnosed?

Anaplasmosis is diagnosed by combining the following tests:

Complete Blood Count (CBC): This is the first step to check for low platelet counts, abnormal white blood cell levels, and anemia.

Blood Smear Examination: This allows direct visualization of Anaplasma morulae inside white blood cells under a microscope.

PCR Test: This is the most accurate method for detecting the pathogen's DNA in the blood.

Antibody Test (ELISA/IFA): Since results may be negative in the early stages of infection, this test is used in conjunction with PCR.

Treatment — Antibiotics are Key

Doxycycline: This is the first-line standard treatment for Anaplasma infection. It is typically administered orally for about 2 to 4 weeks (14–28 days) at a dose of 10 mg per kg of body weight once daily, or 5 mg per kg twice daily.

Treatment Response: With appropriate treatment, the prognosis is generally favorable. Most pets show improvement in symptoms, such as a reduction in fever and a return of appetite, shortly after starting antibiotic therapy.

Alternative Antibiotics: Tetracyclines, including doxycycline, are the primary treatment choice. Since Anaplasma bacteria are often resistant to other antibiotic classes like beta-lactams and macrolides, if a pet has a sensitive stomach with severe vomiting or loss of appetite, we may switch to a different drug within the tetracycline class or adjust the administration method.

Supportive Care: If platelet counts are significantly low or if dehydration is present, supportive treatments such as intravenous fluids are administered alongside antibiotics. Blood transfusions may also be considered if necessary.

Post-Treatment Recheck: After completing the treatment course, blood tests are performed to check platelet and white blood cell counts, providing a final assessment of complete recovery.

A puppy receiving an antibiotic prescription at the veterinary clinic

Care Points to Monitor at Home

Here are the key steps to follow at home during treatment:

Complete the full course of antibiotics: Even if symptoms improve, it is essential to finish the entire prescribed duration to prevent recurrence.

Ensure adequate rest: Avoid strenuous exercise while your pet is experiencing joint pain.

Maintain hydration and provide easily digestible food: Even if appetite is low, frequently offer water and soft, gentle foods.

Follow-up examination in 1–2 weeks: A follow-up blood test is necessary to confirm platelet recovery.

Prevention is Best — Consistently Use Tick Preventatives

The most effective prevention is regular tick control. Consistently use monthly spot-on treatments or oral isoxazoline-class medications, and after walks, carefully check the inside of the ears, between the toes, armpits, and groin. If you find a tick, grasp it vertically as close to the skin as possible with tweezers and pull it out slowly without crushing it, to prevent the spread of bacteria.

Dogs with Frequent Outdoor Activities Require Extra Caution

Environments with high tick exposure risk: Dogs that frequently visit grassy areas such as hiking trails, campgrounds, and rural regions have a much higher chance of encountering ticks.

Check preventive medications: Always verify whether tick preventatives have been administered and review the dosing schedule before and after outdoor activities in spring and autumn.

Prompt tick removal: The longer a tick remains attached to the skin, the greater the risk of pathogen transmission; therefore, removing it immediately upon discovery significantly reduces the risk of infection.

Caution with immunosuppression and co-infections: In dogs with weakened immune systems or concurrent tick-borne infections such as ehrlichiosis, even the same infection may present with more severe symptoms.

Regular blood tests: For dogs that engage in frequent outdoor activities, regular blood tests are recommended to detect early signs of infection, such as abnormalities in platelet and white blood cell counts.

A pet owner checking their dog for ticks after a walk

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can Anaplasma infection be transmitted to humans?

Anaplasma phagocytophilum is a zoonotic pathogen. While it does not spread directly from an infected dog to humans, people can become infected if bitten by the same ticks in the shared environment. Finding a tick on your dog is a sign that your entire household has been exposed to tick-infested areas.

How long should I wait after removing the ticks before getting tested?

If your pet develops a high fever or lethargy within one to two weeks after tick removal, seek veterinary care immediately. Even if no symptoms are present, antibody tests often do not turn positive until two to four weeks post-infection, making PCR testing more accurate in the early stages. During peak tick activity seasons, we recommend a blood test two weeks after removing any ticks.

Can the condition recur after treatment is completed?

Completing the full course of antibiotics during the prescribed period significantly reduces the risk of recurrence. However, since reinfection is still possible after treatment, consistent tick prevention is essential. It’s a good idea to have a follow-up blood test 2–4 weeks after treatment to confirm that platelet levels have returned to normal.

How do Anaplasmosis and Ehrlichiosis differ from each other?

Both are tick-borne bacterial diseases, but they are caused by different bacteria. Anaplasmosis is caused by bacteria of the genus Anaplasma, while ehrlichiosis is caused by bacteria of the genus Ehrlichia. The symptoms are very similar, making it difficult to distinguish between them based on clinical signs alone, and co-infections can occur. Fortunately, both diseases can be treated with doxycycline.

Are young puppies and senior dogs at greater risk if they become infected?

Puppies with weakened immune systems and senior dogs may experience symptoms that develop more rapidly and severely. In particular, the risk of bleeding due to low platelet counts is heightened, which may necessitate intensive supportive care. In such cases, fluid therapy is administered alongside more frequent monitoring of blood parameters.

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References

[1] Breitschwerdt EB. Anaplasmosis and Ehrlichiosis. In: Greene CE (ed.), Infectious Diseases of the Dog and Cat, 4th Ed. Elsevier, 2012. Chapter 27.

[2] Schaer M, Gaschen FP (eds.). Clinical Medicine of the Dog and Cat, 4th Ed. CRC Press, 2022.

[3] Bowman DD et al. Georgis' Parasitology for Veterinarians, 10th Ed. Elsevier, 2014. Chapter 2.

[4] Neer TM et al. Consensus Statement on Ehrlichial Disease of Small Animals from the Infectious Disease Study Group of the ACVIM. J Vet Intern Med 16(3):309-315, 2002.