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Key takeaways

Anaplasmosis is a bacterial infection transmitted through a tick bite. Ticks that transmit the disease are found worldwide.

  • Active, outdoor dogs in high density tick areas are most likely to contract the disease
  • Symptoms are generally mild, including loss of appetite, lethargy, fever, joint swelling and stiffness
  • Diagnosis includes an antibody test, and is part of annual screenings in high risk areas
  • Treatment is a round of antibiotics
  • Symptoms tend to clear up within 1-2 days after treatment begins
  • There is no vaccine against anaplasmosis
  • Tick control and prompt removal of ticks are effective preventative strategies against anaplasmosis
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A closer look: Anaplasmosis in Dogs

Anaplasmosis is transmitted through tick bites. The bacteria is not transmitted immediately after attachment, with the odds for transmission increasing over time. It usually takes at least 12-24 hours to transmit anaplasmosis, with another 1-2 weeks before symptoms develop, if any.

Dogs that contract anaplasmosis generally show mild symptoms, if any at all. Treatment is straight-forward, with a round of antibiotics prescribed by a veterinarian.

Anaplasmosis is not a concern for dogs who are kept on a veterinarian-approved flea and tick control plan because these products usually kill ticks before they are attached long enough to transmit a disease.

In high risk areas veterinarians regularly screen healthy dogs for antibodies against Anaplasma during annual heartworm screening.

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Risk factors

Cases of anaplasmosis are usually mild, often showing no symptoms at all.

Tick-borne transmission is the only known origin of anaplasmosis. Indoor dogs and dogs living in lower tick density areas are at lower risk of contracting anaplasmosis. Dogs that are outside regularly in densely tick populated areas are at higher risk.

In the United States, most cases occur in the Northeast, upper Midwest and West Coast. Ticks carrying the disease are found worldwide.

Possible causes

Anaplasmosis is caused by infection with Anaplasma species of bacteria. Not all infections lead to symptoms.

Black-legged ticks (Ixodes spp.), also known as deer ticks, are responsible for spreading most cases of anaplasmosis.

Main symptoms

Some cases may also show signs of dehydration. Not all dogs that contract Anaplasmosis show symptoms.

Testing and diagnosis

Anaplasmosis is diagnosed with a blood test.

Dogs showing clinical symptoms of anaplasmosis typically undergo a full screening process including a physical examination, blood work, urinalysis and diagnostic imaging.

Steps to Recovery

The infection is treated with a round of prescribed antibiotics for 10-21 days. Anti-inflammatories, analgesics, and fluid therapy may also be prescribed as needed.

Dogs with a positive antibody test but no symptoms are usually not treated. Further blood samples may be sent to a lab to confirm infection, and in some cases the usual course of antibiotics may be prescribed as a precaution. Symptoms should dissipate within 1-2 days of starting antibiotics, but it is important to give the medication for the entire duration prescribed.


As a tick-borne illness, general tick prevention strategies apply to prevent anaplasmosis. These include:

  • Use veterinarian recommended tick prevention medication for all exposed pets year round
  • Routine tick-checks and removal
  • Maintain a tick-free household and resistant yards
  • Avoid high density tick environments
  • Annual pet blood tests in endemic areas
  • Reduce or eliminate exposure to tick habitats (long grasses, shrubbery, forested areas) during peak season

There is no vaccine against anaplasmosis. If the infected tick is not removed from the home it may bite and transmit anaplasmosis to a new host. Infected dogs do not directly transmit to other pets or humans unless there is blood-to-blood contact.

Is Anaplasmosis in Dogs common?

Anaplasmosis is common in active outdoor dogs, particularly those living in areas with high tick populations.

Typical Treatment

  • Antibiotics


No Author - Writing for Centers for Disease Control and Prevention
Becky Lundgren, DVM; Jacqueline Brister, DVM - Writing for Veterinary Partner
Dr. Aly Cohen - Writing for Cornell University College of Veterinary Medicine
Becky Lundgren, DVM - Writing for Veterinary Partner
Jacqueline Brister, DVM - Writing for Veterinary Partner
No Author - Writing for Companion Animal Parasite Council
Janet E. Foley, DVM, PhD - Writing for Merck Veterinary Manual
Jennifer H. McQuiston, DVM, MS - Writing for Merck Veterinary Manual

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