Worked example
A 20 kg dog uses the 15 mL/kg initial-bolus reference.
Initial bolus = 20 kg x 15 mL/kg = 300 mL
The arithmetic readback is 300 mL, with reassessment deciding whether any later fluid bolus is relevant.
Live calculator
Fluid bolus calculator
Calculate an initial isotonic-crystalloid bolus volume for dogs and cats from current AAHA reference choices. This tool is arithmetic support only; reassessment determines whether any later bolus is relevant.
Safety checks
- Arithmetic support only.
- This page does not choose when or whether a bolus should be given.
- Verify the final plan against patient reassessment and current protocol.
- Reassess perfusion parameters between boluses per current protocol.
Basis and limits
- Calculation basis: initial bolus volume = body weight in kg x selected initial bolus reference in mL/kg.
- Reference choices: AAHA lists 15–20 mL/kg for dogs and 5–10 mL/kg for cats, then reassessment of perfusion parameters.
- Scope: this tool supports initial-bolus arithmetic. It does not decide when fluids should be given, whether a bolus should be repeated, or what reassessment should show next.
- Before use: verify the current fluid plan, patient reassessment, line setup, and tolerance to fluids.
Formula audit trail
Calculation steps will appear here for verification.
Worked example and practice
Try this case
Estimate the answer before revealing it: a 4 kg cat uses the 5 mL/kg initial-bolus reference.
Reveal worked answer
Initial bolus = 4 kg x 5 mL/kg = 20 mL.
Last reviewed: May 2026
References: Plumb's Veterinary Drug Handbook, Merck Veterinary Manual, BSAVA Formulary, AAHA Guidelines. Verify against current references before clinical use.