Measuring urine output in veterinary medicine | VETgirl Veterinary Continuing Education Videos
In this VETgirl online veterinary continuing education video, we review the importance of measuring urine output (UOP) in your veterinary patients. Urine output monitoring is an easy but valuable measurement for critical patient monitoring. So why measure urine output? Urine production is a sign of renal perfusion, renal function, and patient hydration status. Normal urine output is 1-2 ml/kg/hour in the healthy dog and cat.
The easiest way to perform UOP measurements is to place a sterile, indwelling urinary catheter connected to a closed collection system, which many critical patients (e.g., acute kidney injury patients, feline urethral obstruction, etc.) have already in place. Noncritical, non-ambulatory patients without a urinary catheter can have their urine collected in a large bowl and subsequently measured, also. When placing a urinary catheter, again, sterile technique and routine cleaning and catheter maintenance is imperative.
As urine color can change with various conditions (e.g., hematuria, pigmenturia, trauma, etc.), color alone should not be your only indicator of patient hydration. Measuring and tracking urine specific gravity (USG) can reveal hydration trends, which can help you know how to adjust your fluid rates (with the goal being isosthenuria while on fluid therapy). When determining fluid rates, keep in mind other sources of ongoing fluid loss (e.g., vomiting, diarrhea, wound drainage, NG tube suction from gastric secretions, evaporative losses from excessive panting, etc.). Hence, measuring ins and outs is imperative, particularly in the azotemic patient. The amount of fluids going “in” (e.g., orally, IV) should equal the amount of fluids going “out” (e.g., lost through ongoing sources, urine output, etc.).
Urine output is measured typically about every 4 hours. Simply divide the amount of UOP by 4 hours, and then by the kilogram weight to obtain the ml/kg/hour. Be sure to include urine output monitoring in your next critical patient. Check out our other VETgirl videos for more life saving tips.