Anaplasmosis in Dogs
Veterinary & Aquatic Services Department, Drs. Foster & Smith

Anaplasmosis in dogs is caused by the bacteria Anaplasma phagocytophilum. It used to be known as Ehrlichia equi and Ehrlichia phagocytophilia. The more complete name for the disease is "canine granulocytic anaplasmosis." It commonly affects the platelets in the blood, which are small cellular components found in the blood which help clots to form. Anaplasmosis causes thrombocytopenia, which is a lower than normal number of platelets in the blood.

In the body, microscopically small vessels often break in the normal course of events. Platelets and a protein called fibrinogen 'plug' the break in the vessel and prevent blood from leaking out. When platelet levels are low, bleeding can occur from these vessels. The bleeding may be into the digestive tract, skin, or other organs.

How is anaplasmosis in dogs transmitted?
Anaplasmosis in dogs is transmitted by the bite of ticks, the same ticks that transmit Lyme disease.

What are the symptoms of anaplasmosis in dogs?
Three of the most common signs of anaplasmosis are lethargy, loss of appetite, and fever. These are common signs of many diseases. Other signs that may be seen include pale mucous membranes (e.g., pale gums), vomiting, diarrhea, lameness, nosebleeds, and dark stools (due to the presence of digested blood). Often these symptoms are noticed in spring and fall, when ticks are most abundant. Some dogs can become infected, but show no symptoms. This is called a "subclinical infection."

How is anaplasmosis in dogs diagnosed?
Many of the symptoms of anaplasmosis are common to many different diseases, which makes the disease more difficult to diagnose. On the physical exam, an enlarged spleen is often palpated. A complete blood count generally shows an anemia , low numbers of certain white blood cells called lymphocytes, and low numbers of platelets. Rarely, the A. phagocytophilum may be seen on the blood sample under the microscope. There is an antibody blood test for anaplasmosis, but one sample alone is not sufficiently accurate to make the diagnosis. Instead a test called a polymerase chain reaction (PCR) test is used to identify the presence of the bacteria in the blood.

How is anaplasmosis in dogs treated?
Anaplasmosis in dogs is treated with the antibiotic doxycycline for at least 4 weeks. Reinfection from another tick bite can occur.

How is anaplasmosis in dogs prevented?
Avoiding areas where ticks are in high numbers and using a good tick preventive are the most important things you can do to protect your dog. If you do see a tick on your dog, remove the tick safely. There is no vaccine against anaplasmosis.

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