Effect of diuresis on urinary excretion and creatinine clearance in the horse.

This research examines how diuresis, or increased urine production, affects the clearance of creatinine and the excretion of certain compounds in horses.

Study Summary

• The study focused on the effects of diuresis on endogenous creatinine clearance and the excretion of phenylbutazone, osmotically active materials, and compounds contributing to the urinary refractive index in thoroughbred mares.
• Diuresis was induced in the horses by the administration of water and furosemide, a diuretic commonly used in horses.
• The urine of the horses was collected quantitatively using urinary bladder catheters, allowing precise and accurate analysis of the excreted materials.

Experimental Results

• The experiment commenced without inducing diuresis in the horses, recording a baseline urine flow of around 9 microliters per minute per kilogram of horse weight.
• Following this, diuresis was induced by water administration, leading to a significant increase in urine flow to about 50 microliters per minute per kilogram. This also caused increased creatinine clearance and excretion of phenylbutazone, a nonsteroidal anti-inflammatory drug commonly used in horses.
• Diuresis was then induced by administering furosemide, resulting in the highest observed urine flow of about 70 microliters per minute per kilogram. The effect of furosemide administration differed from water administration; it increased the urinary excretion of osmotically active compounds and substances influencing the urinary refractive index, but interestingly reduced the excretion of phenylbutazone.

Implications of the Study

• This research highlights the substantial effect that induced diuresis can have on the renal function of horses.
• The changes seen in the clearing of creatinine and the excretion of different compounds with increased urine production could significantly impact the pharmacokinetics of drugs or the evaluation of renal function in horses.
• In general, this study underscores the importance of considering urinary flow rates and the factors influencing them when evaluating renal function or managing drug dosages in horse.