Frusemide results in an extracellular to intracellular fluid shift in horses.
BACKGROUND
Frusemide (Lasix) is commonly used diuretic in horse racing and equine clinical practice. While pharmacology, pharmacodynamics, renal and haematological effects of frusemide have been studied in horses, its effects on the distribution of fluid within the horse remain unknown.


OBJECTIVE
To quantify the effects of frusemide on extracellular and intracellular fluid shifts.


METHODS
Horses were infused with 1 mg/kg body mass (n = 7) or 2 mg/kg (n = 9) i.v. frusemide. Total body water (TBW), extracellular fluid volume (ECFV) and plasma volume (PV) were measured using D2O, NaSCN and Evans blue dilution. Change in ECFV was assessed from the change in plasma [protein] and from repeated infusion/dilution of NaSCN.


RESULTS
Frusemide resulted in a 0.020 +/- 0.002 l/kg decrease in TBW within 120 min. At 120 min after frusemide infusion the ECFV losses were nearly double the TBW losses, therefore ECFV loss in excess of TBW loss is seen as an increase in ICFV.


CONCLUSIONS
Frusemide resulted in a net shift of fluid (electrolytes and water) from the extracellular to intracellular fluid compartment.


CONCLUSIONS
The fluid shifts that occur within horses administered frusemide has not previously been characterised. The intracellular shift of fluid is of performance and clinical significance.
Forro
M
M
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Lindinger
M I
MI
D000818:Animals; D001825:Body Fluid Compartments / Q000187:drug effects / Q000502:physiology; D001834:Body Water / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004232:Diuretics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D045604:Extracellular Fluid / Q000187:drug effects*; D005260:Female; D005665:Furosemide / Q000494:pharmacology*; D006736:Horses / Q000378:metabolism*; D007201:Indicator Dilution Techniques / Q000662:veterinary; D007262:Infusions, Intravenous / Q000662:veterinary; D007424:Intracellular Fluid / Q000187:drug effects*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology; D010953:Plasma Volume / Q000187:drug effects / Q000502:physiology / Q000662:veterinary
D004232:Diuretics; D005665:Furosemide