title: Doxycycline clearance of experimentally induced chronic Ehrlichia canis infection in dogs.
abstract: BACKGROUND
  Ineffective clearance of Ehrlichia canis after doxycycline administration has been reported despite the fact that the recommended treatment for canine ehrlichiosis is doxycycline. The effectiveness of doxycycline in clearing E canis infection from the blood and tissues of dogs requires additional evaluation.
  
  
  OBJECTIVE
  Doxycycline (5 mg/kg PO q12h), administered for 4 weeks, will eliminate E canis infection from the blood and tissues of experimentally infected dogs.
  
  
  METHODS
  Fifteen Walker hound-mixed breed dogs were inoculated subcutaneously with E canis-infected canine histiocytic cells 4 months before doxycycline treatment.
  
  
  METHODS
  Four dogs were treated with doxycycline (5 mg/kg PO q12h for 3 weeks), 5 dogs were treated with doxycycline at the same dosage for 4 weeks, and 5 control dogs were not treated. Dexamethasone (0.4 mg/kg i.v.) was given after treatment to precipitate recrudescence of any remaining E canis organisms. Platelet counts, anti-E canis immunofluorescent antibodies, and polymerase chain reaction (PCR) detection of E canis deoxyribonucleic acid (DNA) in blood and tissues were evaluated.
  
  
  RESULTS
  E canis DNA was not detected in the blood and tissues of doxycycline-treated dogs after treatment. Platelet counts were within reference intervals, and E canis antibodies decreased. Spontaneous clearance of E canis infection occurred in 2 of 5 control dogs. Three control dogs had E canis DNA detected in blood and tissues, platelet counts remained low or within the reference interval, and E canis antibodies remained high.
  
  
  CONCLUSIONS
  As administered in this study, doxycycline cleared E canis from the blood and tissues of experimentally infected dogs.
authors.affiliation: Department of Veterinary Clinical Sciences, Louisiana State University, School of Veterinary Medicine, Veterinary Clinical Sciences, Skip Bertman Drive, Baton Rouge, LA 7080, USA. seddlestone@vetmed.lsu.edu
authors.forename: S M
authors.initials: SM
authors.lastname: Eddlestone
authors.forename: P P V P
authors.initials: PP
authors.lastname: Diniz
authors.forename: T M
authors.initials: TM
authors.lastname: Neer
authors.forename: S D
authors.initials: SD
authors.lastname: Gaunt
authors.forename: R
authors.initials: R
authors.lastname: Corstvet
authors.forename: D
authors.initials: D
authors.lastname: Cho
authors.forename: G
authors.initials: G
authors.lastname: Hosgood
authors.forename: B
authors.initials: B
authors.lastname: Hegarty
authors.forename: E B
authors.initials: EB
authors.lastname: Breitschwerdt
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002908:Chronic Disease; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004318:Doxycycline / Q000627:therapeutic use*; D041061:Ehrlichia canis; D016873:Ehrlichiosis / Q000188:drug therapy / Q000662:veterinary*
chemical_list: D000900:Anti-Bacterial Agents; D004318:Doxycycline