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Blood Transfusion Calculator

Dogs & Cats

Species

Choose the target according to clinical status. Normalization of PCV is usually unnecessary.

Enter weight and valid PCV/HCT values to see the estimate.

Donor calculator

Whole-blood ceiling: 18 mL/kg, excluding anticoagulant. No separate recommended volume is assumed.

Donor health, age, body condition, blood typing, infectious-disease screening and local protocols still apply. Screening reference: 20 kg.

Clinical notes
  • Calculated volume is an estimate, not a transfusion prescription.
  • Use the actual measured PCV/HCT of the blood product.
  • Select the target according to clinical status. Normalization is generally unnecessary.
  • Reassess clinical response and PCV/HCT after transfusion.
  • Appropriate typing/crossmatching, donor screening and monitoring remain necessary.
References

Volume = body weight (kg) × species blood-volume estimate × (target PCV − current PCV) ÷ product PCV.

Blood-volume defaults: dog 85 mL/kg; cat 55 mL/kg. Merck ranges: 80–90 and 40–60 mL/kg respectively. These are implementation assumptions within those ranges.

Whole-blood donor ceilings: dog 18 mL/kg (Italian profile); cat 12 mL/kg lean BW (ISFM profile). Volume-only whole-blood estimate using the selected ceiling, excluding anticoagulant. Screening floors apply separately. Whole-blood yield cannot be equated to packed-cell yield. No separate recommended rate is assumed.

Minimum donor weight is volume ÷ ceiling, rounded upward to 1 kg for dogs and 0.1 kg for cats. Screening requirements are separate from this volume-only estimate.

Large-volume cautions use the upper common-dose references: whole blood 12–20 mL/kg; packed cells 6–10 mL/kg (Cornell). Results are never capped.

The 20% default and 20/25% shortcuts are workflow choices, not universal guideline targets. Merck supports individualized endpoints without PCV normalization.

  1. Blood Transfusions in Dogs and Cats

    MSD/Merck Veterinary Manual · Shauna Blois · 2026

  2. 2021 ISFM Consensus Guidelines on the Collection and Administration of Blood and Blood Products in Cats

    Taylor, Spada, Callan et al. · JFMS · 2021

  3. Italian national veterinary blood guideline · 60/CSR

    Conferenza Stato-Regioni · 17 April 2025 · 2025

  4. Comparative Coagulation — Transfusion Guidelines

    Cornell University College of Veterinary Medicine ·

  5. Update on Canine and Feline Blood Donor Screening for Blood-Borne Pathogens

    Wardrop et al. · JVIM · 2016