An update on blood typing, crossmatching, and doing no harm in transfusing dogs and cats - Veterinary Medicine
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An update on blood typing, crossmatching, and doing no harm in transfusing dogs and cats
Let this article help you quickly review blood typing and crossmatching processes so you'll minimize the potential for transfusion reactions. You'll learn about new blood type antigens—Dal in dogs and Mik in cats, and a recently studied extended blood typing kit for dogs.


VETERINARY MEDICINE


DETECTING A TRANSFUSION REACTION

An acute intravascular hemolytic transfusion reaction can occur in type B cats receiving type A blood. A severe reaction most commonly occurs in dogs previously sensitized to DEA 1.1 blood, but it has also been reported in dogs sensitized against DEA 4, Dal, or an unidentified type (non-DEA 1.1, 1.2, 3, 4, 5, 7).1,4,5,7 Signs associated with acute hemolytic transfusion reactions typically begin immediately after initiating the transfusion and may include fever, altered heart rate, hypotension, dyspnea, loss of bladder and bowel control, vomiting, hemoglobinemia, and hemoglobinuria.21 Since the transfused cells undergo hemolysis, the packed cell volume (PCV) fails to rise. Sequelae can include disseminated intravascular coagulation, renal failure, shock, and death. The reaction's severity is associated with the antibody titer and the amount of blood transfused. If any of the signs beyond fever are noted, the transfusion should be stopped and the appropriate therapy should be initiated.

The half-life of type-compatible blood administered to dogs and cats is about three and five weeks, respectively. Delayed transfusion reactions are more insidious than acute reactions and may be overlooked or attributed to other events, such as an antibiotic-related allergy. In these cases, the PCV may rise as expected and then fall over the course of several days to weeks. Since the hemolysis is extravascular, icterus and hyperbilirubinuria may be noted.

A first-time type B transfusion to a type A cat may result in a delayed hemolytic reaction. Delayed reactions may also occur in first-time canine recipients of DEA 1.1 or DEA 7 blood that are negative for those antigens as well as in dogs previously sensitized against weaker antigens. Donors deemed DEA 1 negative may actually be type DEA 1.2 if one relies solely on the in-house typing kit results. Ideally, permanent donors should receive complete typing and antibody screening if possible. The in-house DEA 1.1 typing kits should be reserved for screening potential donors and typing recipients requiring immediate transfusion therapy.

A dog receiving blood type-matched for DEA 1.1 can still be mismatched for any of the other antigens. Universal donors should be positive for DEA 4 only since it is a common antigen and will induce sensitization only in the rare dog that lacks it. However, it is important to remember that universal donor blood is only known to be negative for DEA 1.1, 1.2, 3, 5, and 7. The elusive DEA 6 and 8 and several other antigens for which typing sera do not exist can be present on universal donor erythrocytes and can sensitize a recipient negative for any one or more of those antigens. The Dal antigen also needs to be kept in mind when transfusing Dalmatians.

GUIDE FOR TYPING AND CROSSMATCHING DOGS


Table 2: Process for Typing and Crossmatching Dogs
Crossmatching may not detect low concentrations of antibody or predict the potential to develop antibodies against mismatched blood. Repeat transfusions may be a rare occurrence in some practices, but for those with a high volume of patients with chronic renal disease or receiving chemotherapy or those with tenacious owners battling persistent immune-mediated hemolytic anemia in their pets, repeat transfusions are not uncommon. In these cases in which multiple transfusions are anticipated, donor selection based on blood type can maximize transfusion effectiveness.

Following a few easy steps (Table 2) can help you decide whether a simple DEA 1.1 typing is sufficient or if a more complete typing is needed and whether crossmatching dogs to minimize transfusion reactions and sensitization to transfused blood is necessary. Briefly, DEA 1.1 type-matched blood is adequate for a first-time recipient requiring immediate transfusion therapy. Even if sensitization occurs, the benefits of the transfusion likely outweigh the shortened half-life of transfused cells. Universal donor blood is recommended as a first choice whenever possible and, certainly, when repeated transfusions are anticipated. Crossmatching will not be helpful in a first-time recipient (or recent recipient) but is required if the recipient has received a transfusion four or more days previously or is a Dalmatian. Common antigens that are lacking in a sensitized recipient can make locating compatible donor blood challenging. In these cases, crossmatching against siblings or same-breed donors is more likely to be successful.

Linda M. Vap, DVM, DACVP
Department of Microbiology, Immunology and Pathology
College of Veterinary Medicine and Biomedical Sciences
Colorado State University
Fort Collins, CO 80523


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