Clinical Calculator Guide
Fluid Deficit Guide: Veterinary Dehydration Replacement Planning
Fluid deficit calculations are easy to over-simplify. This guide shows how to convert dehydration percentage into replacement volume while keeping reassessment central.
Last reviewed: February 13, 2026
What This Guide Does
It helps estimate replacement volume, distribute timing, and avoid overcorrection by integrating dynamic clinical reassessment.
The objective is to reduce arithmetic errors, improve clinical consistency, and connect each formula to a practical interpretation step.
How to Use This Guide in Study Blocks
Run one worked example manually, then verify it in the linked tool. Next, answer practice questions that force you to apply the same concept under time pressure. This sequence builds speed and reliability for exam scenarios while also improving day-to-day calculation safety in supervised clinical settings.
Inputs and Outputs
| Input | Definition |
|---|---|
| Body weight | Patient weight in kilograms. |
| Estimated dehydration | Clinical dehydration percentage estimate. |
| Replacement window | Target timeframe for deficit replacement. |
| Output | Definition |
|---|---|
| Deficit volume | Estimated mL needed to replace dehydration deficit. |
| Hourly replacement target | Deficit portion translated to mL/hr over selected window. |
Formula Summary (High Level)
Deficit (mL) = body weight (kg) x dehydration fraction x 1000. Then distribute replacement across chosen hours with reassessment.
Example Calculation
- A 15 kg dog is estimated 8% dehydrated.
- Deficit = 15 x 0.08 x 1000 = 1200 mL.
- If planned over 12 hours, deficit portion is 100 mL/hr before maintenance and ongoing losses.
- Reassess perfusion and hydration signs often and adjust rate rather than locking one static plan.
Common Pitfalls and Safety Checks
- Dehydration percentage is an estimate and should be corrected with serial reassessment.
- Ignoring ongoing losses can underdose total fluid support.
- Replacing full deficit too quickly may stress cardiopulmonary status.
- Maintenance and deficit are separate components and should not be merged blindly.
Related Content
- Return to pillar: Veterinary Calculators Guide: Dose, Fluids, CRI, and Acid-Base Workflows
- Maintenance Fluids Guide for Veterinary Inpatients
- Anion Gap Interpretation Guide for Veterinary Acid-Base Cases
- Use the Fluid Calculator
- Link deficit planning with shock phenotype decisions
- Apply fluid logic in heatstroke stabilization
- Use deficit logic in GDV perfusion planning
- Use normal values to interpret fluid response trends
- Unlock unlimited practice (Premium)
Sources and Review Notes
- Drug label search (DailyMed)
- IRIS stages
- Normal lab values
- Heartworm treatment protocol
- Lab test protocols
- Microchip lookup
- Vertebral Heart Score
- BCS charts
- ACVIM cardiology consensus guideline references
- Dental charts
- AAHA vaccination guidelines
- Flea/tick product info
- Dog/cat breed search
- RECOVER CPR guidelines
Last reviewed: February 13, 2026
Educational only. This page is designed for study and does not replace case-specific diagnosis, local protocols, or direct supervision.