Plasma concentration of furosemide versus specific gravity of urine in predicting dose of administration in race horses.

The research explores the use of plasma concentration levels of furosemide and specific gravity of urine to determine the appropriate dosage of furosemide in race horses suffering from Exercise-Induced Pulmonary Hemorrhage. It finds that these methods are not entirely reliable for predicting the correct dosage, but can be used as a guideline.

Study Objective and Methods

• The aim of the research was to test the applicability of plasma concentration levels of furosemide and specific gravity of urine in determining the correct amounts of furosemide to administer to racehorses experiencing Exercise-Induced Pulmonary Hemorrhage (EIPH).
• The study used racehorses in Illinois and Pennsylvania, classified into non-bleeders (CTL) and certified bleeders (FUR).
• The team tested different doses of furosemide (less than 250, 250, 300, 350, 400 and 500 mg) administered in two ways – as a single intravenous (IV) dose or as a combination of intravenous and intramuscular (IM) doses given 4 hours before the race.
• After the race, plasma and urine samples were obtained for analyzing the furosemide concentration in the plasma and measuring the specific gravity of the urine in both CTL and FUR groups.

Results

• The test results showed a meaningful difference in the specific gravity of urine samples from the CTL group and the FUR group, irrespective of the method of administration. This outcome implies that the specific gravity of urine alone is not a reliable predictor of the correct dosage or method of administration of furosemide to racehorses.
• Furthermore, the study found that the plasma concentration levels of furosemide were not distinctly different when 250 mg or 500 mg was administered 4 hours before the race. This suggests that the majority of the horses had furosemide plasma concentration less than 40 ng/ml, which indicates that plasma concentration of furosemide can only be used as a guide rather than an exact determinant in regulating the administration of furosemide to racehorses.

Conclusion

• The research concludes that while the plasma concentration of furosemide and the specific gravity of urine can provide some guidance, these markers cannot be utilised to accurately predict the correct dosage or method of administration of furosemide to racehorses suffering from EIPH.