Calculator
CRI Calculator for Dogs & Cats (Constant-Rate Infusion)
Constant-rate infusion maths in mcg/kg/min, mcg/kg/h, mg/kg/h or mg/kg/day — either the drug to add to a fluid bag, or the syringe-pump rate for undiluted drug.
Results are calculated in your browser. Always double-check before administering and use your clinical judgement.
How it is calculated
Drug needed (mg/h) = dose rate × weight, converted to mg per hour (mcg/kg/min × kg × 60 ÷ 1000).
Bag method: mg to add = (mg/h ÷ fluid rate mL/h) × bag volume (mL).
Syringe pump: pump rate (mL/h) = mg/h ÷ drug concentration (mg/mL).
Worked example
20 kg at 2 mcg/kg/min = 2.4 mg/h; at 50 mL/h a 500 mL bag needs 24 mg (2.4 mL of 10 mg/mL).
More dosing calculators
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Ask WeVet about thisFor veterinary professionals. Information supports — never replaces — clinical judgement; always check the current product label and local regulations.