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 25-28 September, 2018 | Singapore
transfusion reactions. Standard laboratory tube and gel column crossmatching techniques, but also in-clinic gel tube (DMS) and strip kits are now available. Screening feline blood donors and patients for the presence of naturally occurring alloantibodies (AB and Mik systems) prove necessary in clinical practice. The presence of autoagglutination or severe hemolysis may preclude the crossmatch testing.
The major crossmatch tests for alloantibodies in the recipient’s plasma against donor cells, whereas the minor crossmatch test looks for alloantibodies in the donor’s plasma against the recipient’s red blood cells. Mixing
a drop of donor/recipient blood with donor/recipient plasma will detect A-B incompatibilities if typing is not available. However, proper techniques for crossmatching and experience are required to detect other less severe incompatibilities. A major crossmatch incompatibility
is of greatest importance because it predicts that the transfused donor cells will be attacked by the patient’s plasma, thereby causing a potentially life-threatening acute hemolytic transfusion reaction. As fatal reactions may occur with <1ml of incompatible blood, compatibility testing by administering a small amount of blood is
not appropriate. This has been shown in experimental studies to result in fatal reactions. The major and minor crossmatch can show incompatibility prior to any transfusion due to the presence of naturally occurring alloantibodies in cats, not only for the AB but also the Mik and possibly other blood group systems.
Previously transfused cats should always be crossmatched, even when receiving blood from
the same donor. The time span between the initial transfusion and incompatibility reactions may be as short as 4 days and lasts for many years (i.e., years after the last transfusion alloantibodies may be present). Obviously, a blood donor should never have received a blood transfusion to avoid sensitization.
Xenotransfusion: Occasionally anemic cats are given canine blood because either no feline blood is available or the feline blood is incompatible (AB, mik and other mismatch). In a recent study by the author’s laboratory (Euler et al 2016) we determined that canine blood
is incompatible and very short-lived (<4 days) in cats. Therefore, we do not recommend such xenotransfusions (Euler et al 2016). Apparently, Oxyglobin, a highly purified bovine hemoglobin solution should be again shortly available in the USA as it has been in Europe.
Feline blood donors: There are few commercial blood bank that offer feline blood products. Many hospitals have a small in-house colony and/or involve the staff’s
or client’s cats. Healthy, young adult (1-8 years), good tempered cats of at least 4 kg lean body weight can
be recruited. Due to the infectious disease risks indoor cats free of fleas and intestinal parasites are selected. A freely roaming cat in a veterinary hospital would not be a good donor candidate because of the potential of having
acquired some infections from patients.
Blood donors must have no history of prior transfusion; have been regularly vaccinated and are healthy as determined by history, physical examination, and laboratory tests (complete blood cell count, chemistry screen, and fecal parasite examination every 6-12 months) as well as free of infectious diseases (testing depends on geographic area but may include
regular FeLV, FIV, FIP, Hemomycoplasma, Cytauzoon testing. Donors should receive a well-balanced, high performance diet, and may be supplemented twice weekly with ferrous sulfate (Feosal, 10 mg/kg), if bled several times a year. Packed cell volume (PCV) or hemoglobin (Hb) should be >35% and >12 g/dl in cats.
Blood collection: Cats are regularly sedated e.g. with
a combination of ketamine (10 mg), diazepam (0.5 mg), and atropine (0.04 mg) by intravenous injection. Some sedatives, such as acepromazine, interfere with platelet function and induce hypotension, hence they should
not be used. Blood is collected aseptically by gravity or blood bank vacuum pump from the jugular vein over 5
to 10 minute period. Large plastic syringe containing 1
ml CPD-A or 3.8% citrate per 9 ml blood and connected to a 19 gauge butterfly needle is commonly used for cats. This represents an open collection system in which connections allow exposure of blood to the environment; because of the potential risk for bacterial contamination, blood collected via an open system should not be stored for more than 48 hours. The maximal blood volume to
be donated is 40-50 ml blood (one typical feline unit) per ≥ 5 kg cat. We have developed a closed blood collection system that permits component preparation into packed red blood cells and fresh frozen plasma as well as storage (28 days of red cells, 1 year FFP). Blood components are prepared from a single donation of blood by simple physical separation methods such as centrifugation generally within 4 hours from collection.
Blood administration: The regular principles used in transfusing dogs are applied in cats. No food is given during the transfusion, and blood is administered separately without any drugs or other fluids. Because
of the small volumes shorter tubing with a small filter
are used instead of the large infusion sets. Despite assuring blood compatibility particular attention is given to the first few milliliters infused. Monitoring is done like in dogs. Transfusion reactions may be related to blood type incompatibilities but also allergic reactions, physical hemolysis, hypocalcemia, and infection.
Author’s studies were supported in part by grants from the National Institutes of Health (OD010939) and the Winn Feline and other Foundations. The author is the director of the non-for-profit PennGen Laboratory which is offering genetic, hematological and blood typing and compatibility testing.

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