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Definition

Transfused blood may transmit infection due to unrecognized donor infection or due to bacterial overgrowth in the blood product.

Risk factors

 Improper collection and storage of blood, including skin contamination during collection, refrigeration without strict temperature control, break in sterility during warming or administration of blood

 Blood‐borne disease in donor horse

Pathogenesis

Bacterial contamination can occur at many points during the collection, storage, and administration of blood products. Horses are most often transfused with fresh whole blood, so the risk of substantial bacterial contamination is low since the blood is not stored. Donor horses may transmit viral, bacterial, and protozoal diseases, such as equine infectious anemia (EIA), piroplasmosis, and equine parvovirus.

Prevention

The USDA issues standards for equine plasma labelled for treatment of failure of passive transfer of immunity and treatment of specific diseases. These standards include testing plasma donors for EIA, piroplasmosis, dourine, glanders, and brucellosis. The USDA recommends additional testing for equine viral arteritis, West Nile virus, and equine parvovirus. The USDA does not have regulatory oversight of whole blood or packed RBCs, but the guidelines for plasma donors are logical for blood donors as well. Blood donors should not give blood if they are showing any signs of illness, including fever.

The blood collection site (usually jugular vein) should be clipped and prepared with a surgical scrub, especially if blood will be stored. Sterile technique should be used with needle or catheter placement and a closed collection system should be used to limit potential for bacterial contamination. Stored blood should not be used if there are any signs of contamination or disruption of the bag. Do not leave blood products at room temperature for more than 4–6 hours.

Diagnosis

Bacterial contamination and production of toxins may result in immediate clinical signs of systemic inflammatory response syndrome in the transfused patient. Fever, tachypnea, and tachycardia can occur for a variety of reasons during transfusion, and regardless of the suspected cause, the transfusion should be stopped. Unfortunately, transmission of viral or protozoal disease will not be immediately apparent, so prevention through donor testing is strongly recommended.

Treatment

The transfusion should be stopped if there are any signs of reaction or suspicion of contamination. Any remaining donor blood can be cultured if bacterial contamination is suspected.

Expected outcome

Outcome will depend on the underlying infection. In humans, approximately 10% of transfusion‐related deaths were due to transfusion‐transmitted infections [19].