Clinical signs of a severe acute hemolytic reaction are, unfortunately, non-specific and include tachycardia, dyspnea, collapse, hypotension, salivation, tremors, convulsions, weakness, vomiting and pyrexia. Extravascular hemolysis is due to destruction of antibody-coated donor erythrocytes by the macrophages in the spleen and liver, leading to hyperbilirubinemia and bilirubinuria. Clinical signs are generally milder than those produced by intravascular hemolysis. If an acute hemolytic reaction develops, the transfusion should be immediately stopped and supportive therapy instituted. This includes administration of intravenous fluids to combat hypotension and shock and maintain renal perfusion.
Some authors also advocate the use of corticosteroids with or without low doses of dopamine.
In general, acute hemolytic transfusion reactions can be prevented by crossmatching or using only matched typed blood. This reaction may occur in dogs that are administered incompatible blood on the first transfusion. It takes about 7 to 10 days to get an antibody response to the foreign red cells, thus after the production of antibody, there is accelerated removal of the donor erythrocytes and the transfusion does not last as long as it should. Delayed hemolytic reactions are usually mild and may not be recognized. The most common signs are fever, anorexia and jaundice.