Canine Anaplasmosis: A Vet's Guide by Catherine Barnette, DVM, Reviewed by Rhiannon Koehler, DVM, MPH. Updated on April 28, 2023. (Share on Facebook, Twitter, or Email)

Discovering a Tick on Your Canine Companion Can Be Alarming

Ticks are not only unsightly, but they can also transmit various illnesses, including a bacterial infection known as anaplasmosis. According to the Companion Animal Parasite Council, nearly 4 percent of dogs in the United States tested positive for anaplasmosis exposure in 2022.

Anaplasmosis is caused by two types of bacteria: Anaplasma phagocytophilum and Anaplasma platys. The former causes dog tick fever, a form of anaplasmosis that occurs worldwide, with most cases reported in the Northeast and upper Midwest regions of the U.S. A. phagocytophilum is transmitted by deer ticks, Western black-legged ticks, and castor bean ticks.

A. platys is responsible for infectious cyclic thrombocytopenia, a less common form of anaplasmosis that affects dogs worldwide. This bacterium is spread by the brown dog tick.

Most dogs do not show symptoms after being bitten by an infected tick, but if symptoms do appear, they typically emerge one to two weeks after the bite. While mild symptoms are common, the infection can be severe in some cases.

What Causes Anaplasmosis in Dogs?

Anaplasmosis is transmitted through the bite of an infected tick that has fed on the dog for at least 12-24 hours. During feeding, bacteria move from the tick's gut to its mouth and are then injected into the dog's blood and tissues. It has been observed that Labrador Retrievers and Golden Retrievers may be more susceptible to this infection, but the reason behind this remains unclear.

Symptoms of Anaplasmosis in Dogs

Symptomatic anaplasmosis in dogs is common, but some dogs may not show symptoms of the disease.

Dogs infected with A. phagocytophilum typically develop a flu-like illness, referred to as dog tick fever or dog fever. After an initial illness, flu-like signs often resolve without treatment, but if the infection progresses, symptoms of joint inflammation may develop throughout the body. Affected dogs may limp, and visible swelling of the joints may be observed.

The symptoms of A. phagocytophilum infection include:

Lethargy
Fever
Decreased appetite
Vomiting
Diarrhea
Coughing
Shortness of breath
Limping
Generalized discomfort
Joint stiffness or pain
Visible swelling of the joints

Dogs infected with A. platys develop a different set of symptoms, which include fever, nosebleeds, unexplained bruising, pale gums, and enlarged lymph nodes.

Diagnosing Anaplasmosis in Dogs

To diagnose anaplasmosis, your veterinarian will first perform a thorough physical exam and obtain a complete medical history. Next, your veterinarian is likely to recommend blood tests, including a complete blood cell count (CBC) and serum biochemistry. Typically, a dog with anaplasmosis will have a low platelet count on the CBC, as well as anemia and changes in white blood cells. A serum biochemistry profile may show increases in liver enzymes and proteins associated with inflammation. In some cases, the organism can be seen in the blood with the aid of a microscope.

If the physical exam and bloodwork findings suggest the possibility of a tick-borne disease, your veterinarian will perform additional tests to confirm the presence of anaplasmosis. An in-house test is commonly used, which requires only a few drops of blood and provides results within 10 minutes. However, this test does not distinguish between active infection and previous exposure. A positive test may indicate that the dog has been exposed to anaplasmosis.

Treating Anaplasmosis in Dogs

As a bacterial infection, anaplasmosis is treated with antibiotics. Dogs typically start to improve within 24-48 hours of receiving antibiotics, and the course of treatment lasts at least three to four weeks. In more severe cases, hospitalization, intravenous fluids, pain medications, and, in some cases, blood transfusions may be required.

If your dog tests positive for anaplasmosis, your veterinarian will prescribe the appropriate antibiotic and discuss any potentially adverse side effects. Commonly, doxycycline is the antibiotic of choice to treat anaplasmosis in dogs. Non-steroidal anti-inflammatory medications may also be prescribed to alleviate pain and inflammation.

Preventing Anaplasmosis in Dogs

The best way to prevent anaplasmosis is to ensure that your pet receives year-round flea and tick prevention. By preventing ticks from attaching to your dog for 24 hours, anaplasmosis transmission can be stopped. Talk to your veterinarian to determine the best preventive measures for your dog.

If you find a tick on your dog, remove it promptly using tweezers. Grasp the tick's head as close to the skin as possible and pull gently to remove the entire tick, including the head. Pieces of the tick head can be left behind and will be expelled by the dog's body over time. If you spend a lot of time outdoors with your dog, make sure to regularly check for ticks.

Regularly checking one's pet's health-and-wellness, including mental-health through lifestyle habits, can help in detecting ticks early, potentially preventing the transmission of tick-borne diseases like anaplasmosis.
Understanding the common symptoms of anaplasmosis in dogs, such as lethargy, fever, decreased appetite, and joint inflammation, can aid in timely diagnosis and treatment, ensuring better health for pets.