title: Antimicrobial use in critically ill horses.
abstract: OBJECTIVE
  To discuss controversies surrounding antimicrobial use in critically ill horses.
  
  
  METHODS
  PubMed searches from 1970-present for terms including, but not limited to: "horse," "foal," "antimicrobial," "prophylaxis," "infection," "surgery," "sepsis," and "antimicrobial resistance."
  
  
  RESULTS
  Increasing bacterial antimicrobial resistance has changed first-line antimicrobial choices and prompted shortening of the duration of prophylactic and therapeutic treatment. The need to decrease bacterial resistance development to critically important antimicrobials has been highlighted.
  
  
  RESULTS
  Veterinary medicine has followed a similar trend but often without a high-level evidence. Common dilemmas include diseases in which the theoretically most effective drug is a reserved antimicrobial, the inability to differentiate infectious from noninfectious disease, the duration and necessity of prophylactic antimicrobials and use of antimicrobials in primary gastrointestinal disease. These problems are illustrated using examples of purulent infections, neonatal sepsis, colic surgery, and treatment of colitis. Although enrofloxacin, cephalosporins, and doxycycline, in contrast to gentamicin, reach therapeutic concentrations within the lungs of healthy horses, the first two should not be used as first line treatment due to their reserved status. Due to the high risk of bacterial sepsis, antimicrobial treatment remains indispensable in compromised neonatal foals but shortening the length of antimicrobial treatment might be prudent. One prospective randomized study demonstrated no difference between 3 and 5 days of perioperative antimicrobial treatment in colic surgery but shorter durations were not evaluated. High-level evidence to recommend antimicrobial treatment of adult horses with undifferentiated diarrhea does not exist.
  
  
  CONCLUSIONS
  Few evidence-based recommendations can be made. Commonly used antimicrobial combinations remain the mainstay for treating purulent infections. Antimicrobial treatment for compromised foals should not extend beyond recovery. Continuation of prophylactic antimicrobials >3 days is likely unnecessary after colic surgery; shorter durations might be equally effective. Antimicrobial prophylaxis in adult horses with diarrhea is unlikely to be beneficial.
authors.affiliation: Department of Clinical Science and Services, The Royal Veterinary College, North Mymms, Hatfield, Hertforshire, United Kingdom, United Kingdom.
authors.forename: Bettina
authors.initials: B
authors.lastname: Dunkel
authors.forename: Imogen C
authors.initials: IC
authors.lastname: Johns
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D019072:Antibiotic Prophylaxis / Q000662:veterinary; D016470:Bacteremia / Q000188:drug therapy / Q000662:veterinary*; D003422:Critical Care; D016638:Critical Illness; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D006801:Humans; D011446:Prospective Studies; D014730:Veterinary Medicine
chemical_list: D000890:Anti-Infective Agents
keywords: antibiotics; diarrhea; equine; pneumonia; prophylaxis; sepsis