Effects of meloxicam and phenylbutazone on renal responses to furosemide, dobutamine, and exercise in horses.

This research investigates how two non-steroidal anti-inflammatory drugs (NSAIDs), namely meloxicam and phenylbutazone, affect kidney function in horses, particularly in response to the drugs furosemide, dobutamine, and exercise.

Methodology

• The research employs a randomized blinded placebo-controlled crossover study involving nine Thoroughbred or Standardbred mares aged between 2 to 12 years.
• Each horse was subjected to three treatments – phenylbutazone, meloxicam, or a placebo – to evaluate their renal responses to applications of furosemide, dobutamine, and exercise for 15 minutes at 60% of their maximum heart rate.
• The renal function was assessed by bilaterally catheterizing the ureters for simultaneous determination of creatinine clearance, sodium excretion, and urine flow rate.

Results

• Both phenylbutazone and meloxicam were found to reduce the effects of diuresis (increased or excessive production of urine) and natriuresis (excretion of sodium in the urine) prompted by furosemide. This also led to a reduction in the glomerular filtration rate, which is a test to measure the level of kidney function and determine the stage of kidney disease.
• After administering dobutamine or conducting exercise, the mean arterial blood pressure, urine flow rate, and glomerular filtration rate were increased.
• Both NSAIDs resulted in reduced urine flow rate and sodium excretion associated with dobutamine infusion and exercise, but these did not impact the glomerular filtration rate.

Conclusion

• The responses to meloxicam, a drug that prefers cyclooxygenase (COX)-2, seemed similar to those from phenylbutazone treatment. This suggests that COX-2 was responsible for causing prostanoid-induced changes to renal function in horses. It further implies that COX-2-preferential agents could potentially have adverse renal effects similar to nonselective COX inhibitors, particularly in horses suffering from volume depletion.