title: Effect of intravenous administration of furosemide on mass-specific maximal oxygen consumption and breathing mechanics in exercising horses.
abstract: OBJECTIVE
  To determine whether i.v. administration of furosemide (250 mg) to horses before maximal exercise affected maximal oxygen consumption (VO2max), breathing mechanics, or gas exchange during exercise.
  
  
  METHODS
  7 healthy, well-conditioned Thoroughbred horses.
  
  
  METHODS
  5 horses initially performed an incremental treadmill exercise test to determine VO2max 4 hours after i.v. administration of furosemide (250 mg i.v.) or placebo (saline [0.9% NaCl] solution). Time to fatigue and distance run were recorded. All 7 horses were then used to determine the effects of furosemide on gas exchange and breathing mechanics at 40, 60, 80, and 100% of VO2max. Horses were weighed immediately before exercise.
  
  
  RESULTS
  Furosemide treatment significantly increased mass-specific VO2max (5.3%), but absolute VO2max was not significantly altered. In the 2 parts of the study, body weights were 2.9 and 2.5% higher when horses were given placebo than when they were given furosemide. Time and distance run at speeds > or = 11.0 m/s were significantly greater following furosemide administration. Furosemide treatment had no effect on breathing mechanics or gas exchange.
  
  
  CONCLUSIONS
  Previous studies have suggested that prerace administration of furosemide may have a positive effect on performance. Results of this study indicate that this may be attributable, in part, to an increase in mass-specific VO2max but not to improvements in breathing mechanics or gas exchange. Most of the increase in mass-specific VO2max appeared to be attributable to weight loss associated with diuresis induced by furosemide.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman 99164-6610, USA.
authors.forename: W M
authors.initials: WM
authors.lastname: Bayly
authors.forename: R F
authors.initials: RF
authors.lastname: Slocombe
authors.forename: H C
authors.initials: HC
authors.lastname: Schott
authors.forename: D R
authors.initials: DR
authors.lastname: Hodgson
mesh_terms: D000818:Animals; D005080:Exercise Test / Q000662:veterinary; D005665:Furosemide / Q000008:administration & dosage / Q000494:pharmacology*; D006736:Horses / Q000502:physiology*; D007275:Injections, Intravenous; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects*; D010805:Physical Conditioning, Animal; D015656:Respiratory Mechanics / Q000187:drug effects* / Q000502:physiology
chemical_list: D005665:Furosemide; D010100:Oxygen