Use of blood and blood products.

It is sometimes necessary for the practitioner to transfuse the ruminant with whole blood or plasma. These techniques are often difficult to perform in practice, are time-consuming, expensive, and stressful to the animal. Acute loss of 20% to 25% of the blood volume will result in marked clinical signs of anemia, including tachycardia and maniacal behavior. The PCV is only a useful tool with which to monitor acute blood loss after intravascular equilibration with other fluid compartments has occurred. An acutely developing PCV of 15% or less may require transfusion. Chronic anemia with PCV of 7% to 12% can be tolerated without transfusion if the animal is not stressed and no further decline in erythrocyte mass occurs. Seventy-five percent of transfused bovine erythrocytes are destroyed within 48 hours of transfusion. A transfusion rate of 10 to 20 mL/kg recipient weight is necessary to result in any appreciable increase in PCV. A nonpregnant donor can contribute 10 to 15 mL of blood/kg body weight at 2- to 4-week intervals. Sodium citrate is an effective anticoagulant, but acid citrate dextrose should be used if blood is to be stored for more than a few hours. Blood should not be stored more than 2 weeks prior to administration. Heparin is an unsuitable anticoagulant because the quantity of heparin required for clot-free blood collection will lead to coagulation defects in the recipient. Blood cross-matching is only rarely performed in the ruminant. In field situations, it is advisable to inject 200 mL of donor blood into the adult recipient and wait 10 minutes. If no reaction occurs, the rest of the blood can probably be safely administered as long as volume overload problems do not develop. Adverse reactions are most commonly seen in very young animals or pregnant cattle. Signs of blood or plasma transfusion reaction include hiccoughing, tachycardia, tachypnea, sweating, muscle tremors, pruritus, salivation, cough, dyspnea, fever, lacrimation, hematuria, hemoglobinuria, collapse, apnea, and opisthotonos. Intravenous epinephrine HCl 1:1000 can be administered (0.2 to 0.5 mL) intravenously or (4 to 5 mL) intramuscularly (preferable) if clinical signs are severe. Pretreatment with antipyretics and slowing the administration rate may decrease the febrile response. Blood or plasma administered too rapidly will also result in signs of cardiovascular overload, acute heart failure, and pulmonary hypertension and edema. Furosemide and slower administration of blood or plasma should alleviate this problem. Administration rates have been suggested starting from 10 mL/kg/hr; faster rates may be necessary in peracute hemorrhage. Plasma should be administered when failure of absorption of passive maternal antibody has occurred or when protein-loosing enteropathy or nephropathy results in a total protein of less than 3 g/dL or less than 1.5 g albumin/dL. Plasma can be stored at household freezer temperatures (-15 to -20 degrees C) for a year; coagulation factors will be destroyed after 2 to 4 months when stored in this manner. To maintain viability of coagulation factors, plasma must be stored at -80 degrees C for less than 12 months. When administering plasma, a blood donor set with a built-in filter should always be used. When bovine plasma is thawed, precipitants form in the plasma and infusion of these microaggregates may result in fatal reactions in the recipient.