1Why are blood groups clinically important in veterinary medicine?
To provide compatible transfusions, prevent neonatal isoerythrolysis, and advise breeders.
2What determines an animal's blood group?
Genetically inherited antigens, usually glycoproteins or glycolipids, on RBC surfaces.
3What does positive or negative mean for an RBC antigen?
Positive means the antigen is present; negative means it is absent.
4What are alloantibodies (isoantibodies)?
Antibodies directed against RBC antigens from another animal of the same species.
5What are naturally occurring alloantibodies? EXAM
Antibodies present without previous transfusion or pregnancy-related sensitization.
- risk of adverse rxn on FIRST transfusion
6What are acquired alloantibodies, and how do they develop?
Antibodies formed after exposure to foreign RBC antigens through mismatched transfusion or pregnancy.
- second time exposed = rxn
7What causes a hemolytic transfusion reaction?
Recipient alloantibodies bind donor RBC antigens, causing agglutination and hemolysis (destruction of transfused RBCs).
8What are the two goals of recipient-donor screening?
Prevent incompatible transfusions and minimize sensitization (new antibody formation) to foreign RBC antigens
9What is the difference between blood typing and crossmatching?
Typing identifies RBC antigens; crossmatching detects antibodies causing donor-recipient incompatibility.
10What is the principle behind blood typing?
Known antibodies (antisera) bind specific patient RBC antigens, producing hemagglutination.
11What are the four methods of blood typing?
Card agglutination, immunochromatographic cartridges, gel column agglutination, and tube agglutination.

12Why can IMHA interfere with blood typing?
Autoagglutination may produce false-positive results; use saline or autoagglutination controls.
- they destroy RBCs so much
13What is the purpose of crossmatching?
To detect antibody-mediated incompatibilities involving RBC antigens, including those not routinely typed. (mix donor + recipient components)
14What is a MAJOR crossmatch? EXAM
Recipient plasma/serum + donor RBCs; detects recipient antibodies against donor cells.

15What is a MINOR crossmatch? EXAM
Donor plasma + recipient RBCs; detects donor antibodies against recipient cells.

16What is the control used during crossmatching?
Recipient plasma + recipient RBCs to detect autoagglutination.

17What findings indicate an incompatible crossmatch?
Agglutination or hemolysis, detected macroscopically or microscopically.

18What does DEA stand for, and which canine antigen is MOST important?
Dog erythrocyte antigen; DEA 1 is most important and occurs in approximately 50–60% of dogs.
- do not have naturally occurring alloantibodies
19Why is canine DEA 1 especially clinically important?
It is highly antigenic and causes strong alloantibody responses after sensitization.
20Do dogs have clinically important naturally occurring alloantibodies?
Generally no; weak natural anti-DEA 3, 5, or 7 antibodies may cause delayed RBC destruction.
21Why is a dog's FIRST mismatched transfusion usually less dangerous than a later one?
Dogs generally lack natural anti-DEA 1, but the first mismatch can sensitize them.
22Which recipients can receive DEA 1-negative donor blood?
Both DEA 1-negative and DEA 1-positive dogs.
23Which recipients can receive DEA 1-positive donor blood?
Only DEA 1-positive dogs; DEA 1-negative recipients should receive DEA 1-negative blood.

24When is crossmatching recommended for a transfusion-naive dog?
It is ideal but not routinely required; it is recommended in IMHA to find a compatible unit.
25When is crossmatching REQUIRED in previously transfused dogs?
If previously transfused more than 4 days ago, even with prior compatible typing or crossmatching.
26What are the three feline AB blood types, and which is most common?
Type A, type B, and type AB; type A is most common, while AB is rare.
27What is the feline Mik antigen?
A non-AB RBC antigen; feline erythrocyte antigen 1 (FEA 1) is believed to be the same as Mik.
28Which naturally occurring alloantibodies do type B cats possess? What happens if a type B cat receives type A blood?
1. STRONG anti-A antibodies.
2. Severe, potentially fatal hemolysis can occur on the FIRST transfusion, even with about 1 mL.
29Which naturally occurring alloantibodies do type A cats possess?
Weak anti-B antibodies, causing shortened survival of transfused type B RBCs.
30Do type AB cats have naturally occurring anti-A or anti-B antibodies?
No; they lack both anti-A and anti-B.
31Why can two cats with matching AB blood types still have incompatible blood?
Mik-negative cats may possess anti-Mik antibodies against Mik-positive donor RBCs.
32What blood typing precautions are emphasized for cats?
Type ALL donors and recipients, and confirm type B or AB results with another method.
33Which RBC blood types should type A and type B cats receive?
Type A cats receive type A; type B cats receive type B.

34What can a type AB cat receive if type AB blood is unavailable?
Type A packed RBCs, because they contain very little donor plasma.
35When should cats be crossmatched?
Before EVERY transfusion is recommended; REQUIRED if previously transfused more than 2 days ago.
36Which feline breeding combination creates the classic risk for neonatal isoerythrolysis?
Type B queen × type A tom, producing type A or AB kittens.
37How does neonatal isoerythrolysis develop in kittens?
Anti-A antibodies in the type B queen's colostrum are absorbed during the first 12–24 hours and destroy kitten RBCs.
38How can feline neonatal isoerythrolysis be prevented?
Type before breeding; for at-risk kittens, avoid the queen's colostrum for ~24 hours and provide a suitable foster queen or milk replacer. The reverse mating is not the classic risk.
39How many major equine blood group systems are recognized?
Seven: A, C, D, K, P, Q, U; more than 30 factors create over 400,000 possible combinations.
40What is the difference between an equine blood group system and factor?
The uppercase letter identifies the system; lowercase identifies its antigen, e.g., Aa is factor a in system A.
41Which three equine RBC factors are MOST clinically relevant?
Aa, Qa, and Ca; Aa and Qa can cause severe reactions and NI, while Ca reactions are usually weaker.

42What is the donkey factor, and why is it important?
An antigen unique to donkeys that horses lack; it contributes to neonatal isoerythrolysis and alloimmune thrombocytopenia in mules.
43Do horses have naturally occurring alloantibodies?
About 90% do not; around 10% have anti-Aa or anti-Ca. Anti-Aa can cause acute hemolysis, while anti-Ca is usually less significant.
44How do horses acquire alloantibodies after sensitization?
Through previous transfusion or pregnancy, especially against highly immunogenic Aa and Qa factors.
45What is the ideal equine blood donor?
An Aa-negative, Qa-negative gelding with no transfusion history and a negative antibody screen; no universal donor exists.
46What pre-transfusion testing is recommended for horses?
Type donor and recipient as closely as possible, especially A, C, Q, and perform a major crossmatch.
47What are the transfusion guidelines for other species with limited blood typing?
Prefer a never-transfused donor of the same species, breed, use a close relative if necessary, and ALWAYS crossmatch.