Canine & Feline Transfusion Medicine: A Practical Clinical Guide

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Key takeaways

• Component therapy beats whole blood when you only need oxygen-carrying capacity or clotting factors.
• Type before elective transfusion; protect DEA 1 negative red-cell stock for dogs that truly need it.
• Start slow (about 0.5–1 mL/kg/h for 15–30 minutes), then titrate to volume status.
• Breached units generally must finish within 4 hours; monitor and document every transfusion.
• Acute reactions are a stop-and-treat emergency — never “push through” fever, collapse, or haemoglobinuria.

When transfusion is indicated

Transfusion is not triggered by a single PCV number. Decide from clinical oxygen delivery, haemorrhage rate, coagulopathy, and the trajectory of the patient. A stable chronic kidney disease cat at PCV 15% is not the same case as an acutely bleeding dog at PCV 20% with tachycardia and lactate rise.

• Red cells: symptomatic anaemia, ongoing haemorrhage, preparation for major surgery with low oxygen-carrying reserve.
• Plasma: clinically important coagulopathy, factor deficiency, some anticoagulant toxicities (product-dependent), not a primary albumin strategy.
• Cryoprecipitate: von Willebrand disease, haemophilia A, hypofibrinogenaemia when available.
• Platelets: life-threatening thrombocytopenia with active bleeding when concentrate is available.

Blood typing essentials

Dogs

DEA 1 is the most clinically important antigen for everyday practice. DEA 1 negative recipients should receive DEA 1 negative red cells whenever possible to avoid sensitisation. DEA 1 negative blood can be used more broadly in true emergencies, but routine typing helps conserve negative units for the patients who need them most.

Cats

AB system incompatibility can cause fatal acute reactions. Type A, B, and AB cats before any transfusion. Type B cats given type A blood are at especially high risk. Never assume “most cats are A” is safe enough without typing.

Cross-matching

Cross-match when the patient has been transfused before, has an uncertain transfusion history, has had a prior reaction, or when delayed serological risk is a concern. Major cross-match checks donor red cells against recipient plasma; minor checks donor plasma against recipient red cells. A compatible cross-match reduces risk — it does not eliminate it.

Dosing rules of thumb

Product	Common starting estimate
Packed RBC	~1 mL/kg raises PCV ~1%
Whole blood	~2 mL/kg raises PCV ~1%
Plasma	10–30 mL/kg to effect
Cryoprecipitate	~1 unit / 10 kg
Platelet concentrate	~1 unit / 10 kg

Use the GlobalVetCo transfusion calculator for bedside volume, drip interval, and duration estimates.

Administration rates

1. First 15–30 minutes: 0.5–1 mL/kg/h while watching closely for reactions.
2. If stable and euvolaemic: often increase toward about 5–10 mL/kg/h.
3. If hypovolaemic / actively bleeding: rates may need to match losses (shock physiology) under direct supervision.
4. If cardiac disease, oliguric renal failure, or volume intolerance: often keep 1–2 mL/kg/h and reassess frequently.

Always use a blood administration set or validated inline filter. Do not run blood with calcium-containing fluids in the same line.

Monitoring & reactions

Record baseline TPR, mucous membrane colour, CRT, mentation, and demeanour. Recheck frequently during the first half hour, then at least every 30–60 minutes. A dedicated transfusion flow sheet helps catch trends early.

Stop the transfusion and treat if you see: sudden fever rise, facial swelling, urticaria, vomiting, restlessness, tachycardia/tachypnoea out of proportion, hypotension, collapse, pigmenturia, or unexpected pain at the catheter site.

For consensus definitions and treatment frameworks, see the AVHTM TRACS transfusion reaction statements (Journal of Veterinary Emergency and Critical Care, 2021) via AVHTM transfusion guidelines.

Storage basics (clinic fridge/freezer discipline)

• Red cells: refrigerated blood bank conditions; never freeze pRBC/whole blood intended for transfusion.
• Plasma products: frozen storage until thaw; follow product-specific thaw and post-thaw timelines.
• Platelets: room-temperature agitation conditions when supplied as concentrate — do not fridge them.
• Log temperatures. If a unit’s cold chain is broken, quarantine and contact your supplier before use.

Traceability

Every transfusion note should include product type, unit ID, expiry, volume given, start/stop times, rates, staff, and reaction details. This protects the patient and allows look-back if a donor unit problem is discovered later.

Red flags

• Transfusing cats without AB typing
• Giving DEA 1 positive red cells to a DEA 1 negative dog when negative units are available
• No filter set / co-infusing incompatible fluids
• Leaving a breached unit hanging beyond 4 hours
• “Mild fever — keep going” without reassessment

Clinical pearls

• Treat the patient, not the number — but do not delay oxygen-carrying support in decompensating anaemia.
• If you only need factors, do not spend red cells.
• Calculate the dose, then check whether the bag volume and 4-hour rule force unit splitting or rate adjustment.
• Build a clinic transfusion kit: typing kits, filter sets, monitoring sheet, calcium gluconate, antihistamine/protocol sheet, and emergency drugs.

Educational content by GlobalVetCo. Not affiliated with Pet Blood Bank UK. Always follow your local regulations, product inserts, and attending clinician judgement.