It's tempting to consider canine ehrlichiosis and canine anaplasmosis as the same thing, because they're spread via pathogen-carrying ticks. The organisms causing the diseases are in the same order -- Rickettsiales -- and are closely related; however, they aren't the same pathogen. Both have a favorable prognosis with proper treatment.
Different Ticks, Different Diseases
According to the Centers for Disease Control, anaplasmosis is spread via the blacklegged tick in the Northeast and the Upper Midwest of the United States and the western blacklegged tick does the job on the West Coast. The lone star tick, found in the eastern and south central United States, is one type of tick responsible for transmitting ehrlichiosis. The brown dog tick, present throughout the United States, carries an additional type of pathogen, Ehrlichia canis, that also causes ehrlichiosis. A dog serves as a great host for any of these ticks, and all it takes is one bite for your pup to become infected with any of these infectious pathogens.
Meeting the Ehrlichia
If your pup picks up an infected brown dog tick or lone star tick, he can experience up to three phases of illness of ehrlichiosis. The acute phase occurs one to three weeks after infection and presents signs such as decreased appetite, enlarged lymph nodes and listlessness. If left untreated, the dog will pass into the second phase, the subclinical phase, where he appears back to good health. This is because the organism has taken up residence in his spleen, where it may lay in wait for months or years. Eventually, he'll enter the chronic phase, where he becomes sick again, potentially developing uveitis, a deep inflammation of his eyes. Lethargy, weight loss and hemorrhaging are also common signs of the chronic phase.
Anaplasmosis carries a wider array of symptoms, including joint pain, lameness, a loss of appetite and lethargy. Less frequently, vomiting and diarrhea will show up, as well as labored breathing and coughing. On rare occasions a dog may have seizures or appear to be in a stupor. Anaplasmosis shares symptoms with Lyme disease; it's not unusual for a dog to be infected with both illnesses at the same time, as the same tick is a carrier for both diseases.
Equal Diagnosis and Treatment
Though the diseases manifest in different ways, diagnosing them is much the same process. The vet will consider your dog's symptoms and run a variety of blood tests, including the enzyme-linked immunosorbent assay, or ELISA, test and the indirect fluorescent antibody, or IFA, test. If the blood tests are conducted at the right moment, the vet may also see the organism through a microscope to confirm diagnosis. Treatment for the diseases is also the same: Doxycycline is often used for both illnesses, requiring at least a month's worth of doses, though some vets prefer tetracycline to treat ehrlichiosis.
- Companion Animal Parasite Council: Ehrlichia spp. and Anaplasma spp.
- Centers for Disease Control: Tickborne Diseases of the U.S.
- VCA Animal Hospitals: Anaplasmosis in Dogs
- University of Wisconsin Madison School of Veterinary Medicine: Ehrlichiosis
- Centers for Disease Control: Geographic Distribution
- dvm360.com: An Update on Anaplasmosis in Dogs
- VeterinaryPartner.com: Ehrlichia Infection in Dogs