how do I recognize and manage an acute transfusion reaction in a dog intraoperatively?

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Intraoperative transfusion reactions in dogs are underdiagnosed because general anesthesia masks the most common presenting signs. The most frequently reported acute reaction — febrile nonhemolytic transfusion reaction (FNHTR) — is difficult to identify under general anesthesia due to anesthesia-induced hypothermia, and the lack of reported reactions in anesthetized dogs likely reflects this diagnostic gap rather than true absence of reactions. 7 Recognition requires heightened vigilance for non-febrile signs. Acute reactions to watch for intraoperatively include hemolysis, respiratory distress, and acute allergic reactions. 1 Transfusion-related acute lung injury (TRALI) — presenting as acute non-cardiogenic pulmonary edema — can develop within hours of packed red blood cell (pRBC) administration and has been documented in dogs, including with associated severe pulmonary hypertension. 4 Transfusion-associated circulatory overload (TACO) presents as acute respiratory distress, tachycardia, and acute or worsening pulmonary edema occurring during or within 6 hours of transfusion. 9 When rapid infusion is used, signs of acute reaction such as fever and vomiting may not be apparent until the entire volume has been delivered. 8 If a reaction is suspected intraoperatively, stop the transfusion immediately and reassess the patient. Vital signs should be assessed every 15 minutes during the first hour of transfusion, hourly until completion, then at 15 minutes, 1 hour, and 24 hours post-transfusion — this monitoring schedule applies regardless of anesthetic status. 1 Packed cell volume (PCV) should be assessed at transfusion completion to evaluate efficacy. 1 Two modifiable risk factors directly increase reaction risk and should be addressed before transfusion begins. pRBC units stored longer than 28 days are associated with higher odds of FNHTR and acute hemolytic transfusion reaction compared with units stored 14 days or fewer. 2 Higher pRBC dose is also associated with h