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Clinical reference

Blood transfusion: dog and cat

A professional reference for veterinary specialists. It does not replace clinical judgement.

There is no universal PCV/Hct transfusion threshold
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.

No isolated PCV/Hct value is an automatic indication for transfusion. A clinically stable patient with chronic anaemia may be well adapted, while acute or ongoing blood loss can require transfusion at a higher or initially normal PCV/Hct. Decide from the whole clinical picture and the trend, not from one number.

Practical grading of anaemia
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.

These Hct/PCV categories describe the degree of anaemia; they are not transfusion triggers. The ranges are approximate and subjective. Interpret them against the laboratory reference interval, hydration, breed, age, trend and clinical condition.

GradeDogCat
Within reference interval41–58%31–48%
Mild30–40%25–30%
Moderate20–<30%15–<25%
Severe<20%<15%
Hydration can mask or exaggerate anaemia. Dehydration reduces plasma volume and can make PCV/Hct appear higher, sometimes concealing anaemia until rehydration. Recent or excessive fluid administration can lower it through haemodilution. Interpret the value with hydration status, total protein or albumin, fluid history and repeat measurements.
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.

Red-cell transfusion calculator
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.

Use it to estimate how much blood product is needed to reach the chosen PCV/Hct, or the expected PCV/Hct after a planned volume. Whether the patient needs a transfusion still depends on the clinical picture.

Use the actual product PCV/Hct whenever available. The circulating blood-volume assumption is visible and editable: the starting value is 90 ml/kg for dogs and 60 ml/kg for cats.

There is no universal maximum volume. Conventional initial volumes are 6–10 ml/kg for packed red cells and 10–22 ml/kg for whole blood. A calculated volume above the selected range should trigger a check of every input, staged administration and reassessment; volume tolerance depends on the patient and ongoing losses.
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Reference book
A veterinary reference written and reviewed by specialists, summarising accepted practice. The product label gives the authorised dose.

When red-cell transfusion should be considered
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.

  • Clinical signs attributable to reduced oxygen delivery: weakness or collapse, reduced mentation or exercise tolerance, persistent tachycardia or tachypnoea, weak pulses or hypotension after perfusion and volume status have been assessed.
  • Acute or ongoing haemorrhage or rapid haemolysis with haemodynamic instability, worsening signs or an anticipated PCV/Hct fall after non-blood fluid resuscitation.
  • Severe anaemia that prevents stabilisation or a necessary procedure, judged together with the cause, speed of onset, trend, lactate and response to initial treatment.

Not an indication by itself

  • A single PCV/Hct value in an otherwise stable and well-adapted patient.
  • Pale mucous membranes without evidence of impaired oxygen delivery or deterioration.
  • An attempt to return PCV/Hct to the normal reference interval. The target is the minimum increase needed to improve oxygen delivery, followed by reassessment.

Canine-to-feline xenotransfusion
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.
Scientific article
A study or review published in a scientific journal. Its findings apply to the animals and conditions it studied.

An emergency bridge only, not an equivalent substitute for compatible feline blood.

  • Consider only for a cat with life-threatening anaemia when compatible feline red cells cannot be obtained in time and waiting is expected to be more dangerous than xenotransfusion.
  • Use canine packed red cells or whole blood according to the clinical goal, perform canine-to-feline major crossmatching where feasible, and monitor exactly as for a high-risk transfusion. Cross-species incompatibility is common in laboratory testing.
  • Expect a short-lived benefit. Canine erythrocytes are removed rapidly and delayed haemolysis commonly develops over the following days; arrange PCV/Hct and haemolysis monitoring and explain this to the owner.
  • Do not repeat canine red-cell transfusion after antibodies may have developed. A subsequent exposure after several days can cause severe, potentially fatal anaphylaxis.
  • Record xenotransfusion prominently in the permanent medical history, including date, canine donor/product, volume and reactions, so it cannot later be mistaken for a feline allotransfusion.

Before starting
Guideline or consensus statement
Recommendations agreed by a panel of veterinary specialists after reviewing the evidence. They guide practice and do not authorise a product.

  • Document the indication, anaemia mechanism and trend, current perfusion, vital signs and planned endpoint.
  • Select the component for the clinical goal: packed red cells add oxygen-carrying capacity with less volume; whole blood may be appropriate when red-cell loss and volume loss coexist.
  • Compatibility first: type cats and use compatible blood; perform a major crossmatch. In dogs, type-match for DEA 1 and crossmatch when previously transfused or the history is unknown.
  • Assess circulatory-overload risk, particularly in cats and patients with cardiac or renal disease, chronic severe anaemia or normal/high circulating volume.
  • Use a blood filter and a monitoring plan. Record temperature, heart and respiratory rate, mucous membranes, pulse quality and blood pressure before and repeatedly during transfusion.
Sources

Professional reference for veterinary professionals. Not advertising and not a substitute for the product label/SPC.

For veterinary professionals only. It does not replace clinical judgement or the product label; check the dose in the official label (SPC). vetman is not liable for harm caused by using this information.

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This reference is still growing. Missing a product? Let us know. · Report an error or request an addition · Updated: 24 Oct 2026

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