How much blood do you transfuse a dog or cat?

Name: Vetinuity
Brand: Vetinuity

Vetinuity's transfusion table: volume (mL) = weight x blood volume (90 mL/kg dog, 60 mL/kg cat) x (target PCV - patient PCV) / donor PCV; pRBC 10-15 mL/kg raises PCV about 10%.

Updated October 2026

By Vetinuity, founded by Brian Toncray, DVM, emergency veterinarian

● VETINUITY TRANSFUSION DOSE CALCULATOR

Vetinuity transfusion dose calculator

Starting volumes by product. For a PCV target, use the formula on this page or the transfusion calculator.

Weight (kg)

Drug	Dose	Route
Packed red blood cells	mL/kg	IV over up to 4 h
Fresh whole blood	mL/kg	IV over up to 4 h
Fresh frozen plasma	mL/kg	IV over 2 to 4 h
Test rate, first 15 to 30 min	mL/kg	IV, per hour

● WHAT'S DOCUMENTED

Vetinuity’s transfusion table: the volume to give is the patient’s weight in kg times its blood volume (about 90 mL/kg in dogs, 60 mL/kg in cats) times the desired rise in PCV divided by the donor PCV; as a quick check, 10 to 15 mL/kg of packed red cells or about 20 mL/kg of whole blood raises PCV by roughly 10 percentage points, and fresh frozen plasma runs 10 to 20 mL/kg. The Vetinuity transfusion dose calculator above gives the starting volume of each product, and the blood transfusion calculator solves the PCV formula. Vetinuity, the clinical assistant, is the work of Brian Toncray, DVM, an emergency veterinarian.

Worked example

A 25 kg dog with IMHA has a PCV of 12% and the target is 20%. Packed red cells from the blood bank have a PCV of 60%. Volume = 25 x 90 x (20 - 12) / 60 = 300 mL, about 12 mL/kg.

Rates and monitoring

Start at 0.25 to 0.5 mL/kg/h for the first 15 to 30 minutes while recording temperature, heart rate, respiratory rate and blood pressure every 5 to 15 minutes, then raise the rate so the unit finishes within 4 hours of leaving storage. Use a filter set. Stop and reassess for fever, hives, vomiting, tachycardia, hemolysis (pink plasma) or dyspnea; the TRACS consensus defines each reaction type.

Matching blood to patient

Species	Before first transfusion	Before later transfusions
Dog	DEA 1 type when possible	Crossmatch if transfused more than about 4 days ago
Cat	Always type (A, B, AB)	Type and crossmatch

Plasma corrects clotting factors in rodenticide coagulopathy, DIC and liver failure, but raises albumin only slowly. Recheck PCV 1 to 2 hours and 24 hours after a red cell transfusion; a lower-than-expected rise in IMHA usually means ongoing destruction, not a wrong dose.

● SOURCES

1. Davidow EB, Blois SL, Goy-Thollot I, et al. Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS). Part 1: Definitions and clinical signs. J Vet Emerg Crit Care (San Antonio). 2021;31(2):141-166. PMID 33792171. Definitions; monitoring. Checked 2026-10-26.
2. Merck Veterinary Manual: Blood Transfusions in Dogs and Cats. Administration. Checked 2026-10-26.

● RELATED ANSWERS

IMHA Treatment Protocol in Dogs
Evidence-based canine IMHA treatment protocol from the 2019 ACVIM consensus, with antithrombotics per the ACVECC CURATIVE guidelines.
Rat Poison in Dogs: Vitamin K1 Dose and Duration
Vitamin K1 at 2.5 mg/kg PO every 12 hours or 5 mg/kg PO every 24 hours for four weeks with a fatty meal, then a PT check after the last dose.
GDV in Dogs: Emergency Stabilization Steps
Vetinuity's GDV table: two large forelimb catheters, crystalloid boluses of 20 mL/kg, gastric decompression by trocar or tube, a full mu opioid and lidocaine 2 mg/kg IV then 50 mcg/kg/min.
Shock Fluid Bolus Volumes for Dogs and Cats
Vetinuity's shock bolus table: isotonic crystalloid 10-20 mL/kg over 15-30 minutes in dogs and 5-10 mL/kg in cats, reassessed after each, or 7.5% hypertonic saline at 3-5 mL/kg in dogs.
Heatstroke in Dogs: Cooling, Fluids and Plasma
Vetinuity's heatstroke table: cool with room-temperature water and moving air, stop active cooling at 39.5 C (103.1 F), give crystalloids to effect and plasma for coagulopathy.

● FAQ

Do cats need blood typing before the first transfusion?

Always. Cats carry naturally occurring alloantibodies, and a type B cat given type A blood can die from a reaction to the first transfusion.

When does a dog need a crossmatch?

Before any transfusion if the dog was transfused before, or has an unknown transfusion history, because antibodies form after the first exposure.

● OPEN APP

SEE HOW VETINUITY HANDLES THIS.

Vetinuity explains clinical options with journal citations.

The veterinarian diagnoses and prescribes.

Open Vetinuity → See full pricing →