Massive transfusion in the dog: metabolic complications
32 kg Golden Retriever with haemoabdomen from a ruptured splenic mass. Over the last 8 hours he has received about 3 litres of packed red cells and fresh frozen plasma. He now has facial tremors, hypotension unresponsive to fluids and a prolonged QT interval.
| Parameter | Result | Reference |
|---|---|---|
| Haematocrit | 30% | 37–55 |
| Total calcium | 9.4 mg/dL | 9.0–11.5 |
| Ionised calcium | 0.72 mmol/L | 1.20–1.40 |
| Ionised magnesium | 0.38 mmol/L | 0.43–0.60 |
| Potassium | 4.6 mmol/L | 3.5–5.1 |
| Temperature | 37.4 °C | 38.0–39.2 |
What best explains the tremors and refractory hypotension?
chevron_right Show answer and explanation
A. Acute haemolytic reaction due to red-cell incompatibility
It would cause haemoglobinaemia, haemoglobinuria and fever, which are not described, and would not explain the very low ionised calcium.
B. Calcium chelation by the citrate in the blood products
Correct. The citrate in the anticoagulant binds ionised calcium and, with massive volumes, the liver cannot metabolise it in time. Ionised hypocalcaemia reduces contractility and vascular tone and causes tremors; total calcium may be normal. Treat with slow IV calcium gluconate under ECG monitoring.
C. Hyperkalaemia from lysis of stored red cells
Potassium is normal; moreover, the red cells of most dogs contain little potassium, so this risk is lower than in humans.
D. Hypothermia from giving unwarmed blood products
Temperature is only slightly low and does not explain tremors with a long QT; hypothermia does contribute to coagulopathy, and products should be warmed.
lightbulb Key takeaway
Massive transfusion means replacing one blood volume in 24 hours or half a blood volume within a few hours. Serially measure ionised (not total) calcium, magnesium, potassium, temperature and coagulation: dilutional coagulopathy, hypothermia and acidosis potentiate each other.
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Updated: November 1, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.