title: Acute recumbency associated with Anaplasma phagocytophilum infection in a horse.
abstract: An 11-year-old Hanoverian-cross gelding was evaluated because of acute onset of ataxia, recumbency, and fever. At the stable, this and other horses had recently been infested with ticks. Results of analysis of a sample of CSF were within reference limits, but hematologic abnormalities included lymphopenia, thrombocytopenia, mild anemia, and intracytoplasmic inclusion bodies in neutrophils that were consistent with Anaplasma phagocytophilum (previously Ehrlichia equi). Results of serum biochemical analyses were characteristic of infection and included high, unconjugated bilirubin concentration. Other common causes of recumbency in horses, such as equine protozoal myeloencephalitis, infection with eastern or western equine encephalitis viruses and equine herpesvirus-1, West Nile viral encephalitis, trauma, and metabolic disease, were ruled out. The horse responded quickly to i.v. administration of oxytetracycline and recovered fully within 6 days.
authors.affiliation: Hospital for Large Animals, School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA.
authors.forename: Rose D
authors.initials: RD
authors.lastname: Nolen-Walston
authors.forename: Sarah M
authors.initials: SM
authors.lastname: D'Oench
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Hanelt
authors.forename: Leslie C
authors.initials: LC
authors.lastname: Sharkey
authors.forename: Mary Rose
authors.initials: MR
authors.lastname: Paradis
mesh_terms: D000208:Acute Disease; D041081:Anaplasma phagocytophilum / Q000302:isolation & purification*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D003937:Diagnosis, Differential; D016873:Ehrlichiosis / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy / Q000662:veterinary*; D006098:Granulocytes; D006402:Hematologic Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000662:veterinary; D006734:Horse Diseases / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D006736:Horses; D002479:Inclusion Bodies; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D010118:Oxytetracycline / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D010118:Oxytetracycline