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Red blood cells (Erythrocytes)
- Antigens on surface of RBC stimulate antibody reaction:
- - genetically determined
- - different species have different genes and different animals within a species have different alleles so...
- -- ... different animals can have different red cell antigens
- - all the red cell surface antigens that arise from single alleles at a single locus belong to the same blood group
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Human blood groups
- simplest
- one gene locus with 3 alleles: A, B, O
- Naturally occuring antibodies to "foreign" red blood cells
- Phenotype (blood type)/Genotype/Antibodies in serum:
- - A /AA or AO/Anti-B => universal platelet donor
- - B /BB or BO/Anti-A
- - AB /AB /None => universal recipient
- - O /OO /Anti-B and Anti-A => O- is universal donor
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Determination of the blood group and blood type
- called bloodtyping
- Use reagents containing one antibody
- test for each antigen separately
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Crossmatch
- if can't do bloodtyping, then at the very least do a crossmatch
- Minor - mix donor serum and recipient cells/whole blood
- Major - mix recipient serum and donor cells/whole blood
- can use EDTA, heparin, citrated plasma
- look for agglutination (sandy appearance)
- clear is a match
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Blood transfusion reactions
- can happen even with a blood match
- hemolytic reaction
- anaphylaxis
- Pyrexia (fever)
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Hemolytic reaction
- lysing of red blood cells
- signs (within minutes) include (Sheila has seen the first two):
- - restlessness
- - panting
- - vocalization
- - limb extension
- - opisthotonus - arch back, tail up
- treatment
- - stop transfusion
- - start O2 & fluids, steroids
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Anaphylaxis reaction
- mast cell degranulation, histamine release
- signs (within minutes) include:
- - pruritus (itchiness)
- - urticaria (redness)
- - bronchiospasm
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Pyrexia (fever) reaction
- leukocytes, platelets in donor blood are also antigenic
- antibody response to these can cause an increase in temperature
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Blood groups in cats
- simplest of domestic animals:
- - one gene locus
- - three alleles: A, B, AB (rare)
- - allele A is dominant to allele B
- -- group B animals are homozygous for the B allele (B/B)
- - AB allele is recessive to allele A and co-dominant to allele B
- frequency of blood types depends on geographic location and breed of cat:
- - 95% group A - mostly DSH, DMH, DLH
- - < 5% group B - mostly purebred
- - < 1% AB
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Blood transfusions in cats
- have naturally occuring antibodies to other blood types
- - eg type B naturally have a high titer of anti-A antibodies
- - important to blood type
- > 85% of cats are type A only
- - approx 1/3 of type A cats have circulating antibodies to type B cells (and only weakly)...
- - ... so low risk of reaction
- type AB lack naturally occurring antibodies
- - can get transfusion from any donor
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Blood donor cat
- clinically healthy, free of disease
- packed cell volume (PCV) at top of normal range
- weigh > 5 kg (11 lbs)
- maximum donation volume 10-12 ml/kg
- each transfusion: one unit of blood (50 mls) every 4-6 weeks
- cat easily handled, remain unstressed (stress hormones not good for sick cat), +/- sedation
- post - fluids, good protein meal
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Blood groups in dogs
- red cell surface antigens called "dog erythrocyte antigen" DEA
- 3 differetn blood groups
- - antiserum only available for 5 systems
- - eg DEA 1.1, 1.2, 1.3
- at birth, dogs do not contain naturally occurring antibodes for the red cell surface antigens
- DEA 1.1 has the greatest potential for antigen formation
- ideal blood donor is DEA 1.1 negative and DEA 1.2 negative (negative => not there)
- first transfusions are safe without type/crossmatch
- - after that need to type/crossmatch as it will develop antibodies after first transfusions
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Blood donor dog
- clinically healthy, free of disease
- > 1 year, < 8 years old
- weigh > 25 kg (55 lbs)
- maximum donation volume 16 ml/kg
- each transfusion: one unit of blood (450 mls) every 4 weeks
- easily handled, remain unstressed (stress hormones not good for sick cat)
- post - fluids, good protein meal
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Neonatal isoerythrolysis
- RBC in newborn undergo lysis in the body because of antibodies acquired from the dam
- fetus inherits red cell antigens from sire (as well as dam)
- at paturition, neonatal RBC are absorbed and enter the circulation of the dam
- dam produces antibodies to the foreign RBCs
- antibodies get transferred to the offspring via colostrum
- first pregnancy not a problem for both dogs & cats: dam becomes sensistized
- subsequent offspring receive high levels of antibody to the RBCs through the colostrum
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Neonatal isoerythrolysis Symptoms
- anemia
- jaundice
- lethargy
- increased pulse
- respiration rate
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Neonatal isoerythrolysis Treatment
- don't let them feed from mom, fluids, possibly blood transfusion
- can probably send bloodwork to lab to see if it is this
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