What kind of organism causes equine granulocytic anaplasmosis?
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This is a tricky question to help you remember that two diseases FORMERLY classified as Ehrlichia have now been RE-classified.
The causative organism of equine granulocytic anaplasmosis (a.k.a. anaplasmosis; formerly equine granulocytic ehrlichiosis) was originally classified as Ehrlichia equi, but is now called ANAPLASMA phagocytophilum due to DNA sequencing studies.
Do not confuse equine anaplasmosis, a necrotizing vasculitis, with BOVINE anaplasmosis, which primarily causes an anemia with icterus and fever.
Another name change occurred with the causative organism of Potomac horse fever (PHF), from Ehrlichia risticii to NEOrickettsia risticii.
PHF presents as a febrile colitis/diarrhea, with laminitis 3-5 d after diarrhea in horses of all ages: A big rule out is salmonella (think septicemia/fever + diarrhea).
