Blood groups and transfusion medicine

• Types of feline blood groups

  Pre-formed naturally occurring antibodies against non-self feline blood antigens.

  Type A - carry weak ant—type B antibodies.

  Type B - carry very string anti-type A antibodies.

  Type AB - (rare) carry no antibodies against type A or B antigens.
• Importance of blood typing in cats

  Type A cats will all have antibodies against type B antigens.

  All donor and recipient cats must be blood types prior to transfusion, even in an emergency.
• Mismatched transfusion in cat

  Type A blood to Type B cat:

  • Severe acute haemolytic reaction (intravascular haemolysis of type A blood).
  • Within seconds of receiving transfusion.
  • May be fatal>

  Type B to type A cat:

  • Extravascular haemolysis (milder clinical signs).
  • Low half-life of RBCs, PCV will fall to pre-transfusion levels within days.
• Feline neonatal isoerythrolysis

  Type A or AB kittens born from a type B queen.

  RBCs in the kittens are targeted by anti-A antibodies from the queen (which are present naturally in type B cats from approx. 3 months).

  • These transfer from colostrum while <24hours.

  Fading kittens

  • Red/brown urine, jaundice, anaemia, sudden death; varies subclinical to severe.

  Breeders should be urged to type Queen (and the tom if queen found to be type B).
• Canine blood groups

  There have been over 12 canine red cell surface antigens proposed internationally.

  DEA 1 antigen has the most transfusion significance (highly antigenic).

  This is the only canine blood type that has a commercial test kit widely available.

  Dogs are described as DEA 1 positive (~70%) or DEA 1 negative (~30%).

  • Certain breeds more likely to be a particular type.

  Dogs do not have pre-formed antibodies against non-self canine blood types.
• Blood typing in dogs

  DEA 1 +ve blood should only be administered to a DEA 1 +ve patient.

  • This will prevent sensitising a DEA 1 -ve dog to the DEA 1 antigens.
  • Also reduce chance of delayed haemolytic reaction.

  Subsequent administration of DEA 1+ve to a sensitise DEA -ve dog can produce acute haemolytic transfusion reaction.

  • Potentially fatal!

  No adverse affects if adminster DEA -ve to DEA +ve but not a good use of -ve blood.
• What is Cross-matching in dogs?

  In-vitro test that looks for potential reactions between a donor’s and patients blood.

  These show as agglutination or haemolysis.

  Major cross match:

  • Assesses compatibility between donor red blood cells and patient plasma/serum.

  Minor cross match:

  • Assesses compatibility between donor plasma/ serum and Pateints RBCs.
• Options for cross-matching in dogs

  Manuually in-house if required.

  Rapid Vet-H in house gel cross-match kit.

  Submit to commercial lab (e.g. Idexx).

  
• Why cross match?

  Additional blood groups that can’t be tested in-house.

  • Dogs have many blood types that coexist.
  • Cats likely have additional blood types recognised.

  Aim is to always try and find compatible blood to transfuse
• What do you do if you only have incompatible blood?

  Urgent cases - may need to transfuse despite incompatibility.

  • Can call pet blood bank/ Lab personnel in these circumstances for advice.
  • Generally transfuse the least incompatible
  • Advice should be sought and signed statement from supervising vet.
• When is cross-matching required?

  Cats have naturally occurring antibodies, therefore crossmatching is recommended prior to any transfusion.

  Dogs:

  • If recipient has been previously transfused >4 days prior.
  • History of previous transfusion reaction.Transfusion history unknown.
• Indications for a blood transfusion

  A precise trigger point for when to transfuse a specific patient cannot be given.

  History, present signs and diagnosis impacts decision.
• Imminent triggers for a blood transfusion

  Evidence for circulatory collapse means transfusion is essential.

  Rapid drop in PCV t0 <20% in dogs and <15% in cats.

  Absolute PCV of 15-25%

  • If the PCV is this low then automatic trigger as organ hypoxia is imminent (particularly myocardium).

  Signs of specific organ hypoxia - particularly CNS.

  Clear evidence of reduced oxygen carrying capacity.

  • Tachycardia, tachypnoea, bounding peripheral pulse.
• What are the blood transfusion products?

  Whole blood (fresh or stored)

  • Platelets
  • Packed red cells.
  • Plasma
  • Fresh frozen plasma
  • Cryoprecipitate
  • Cryosupernatant
  • Frozen plasma
• Whole blood transfusion

  Collected aseptically into a closed collection system.

  Single unit contains ~450ml of blood.

  Whole blood (generally FWB) - main purpose is for acute blood loss or active bleeding.

  Fresh (FWB):

  • Transfused within 8 hours of collection
  • Contains all components of blood.

  Stored (SWB):

  • Refrigerated (<4C) and not transfused within 8 hours of collection.
  • 3 weeks
  • Lacks PLTs, WBCs and labile clotting factors
• Packed red blood cells (PRBCs)

  Whole blood centrifuged - separates RBCs from plasma.

  PRBCs suspended in nutrient solution (SAG-M) stored in the fridge for up to 42 days.

  Indicated for any patient developing clinical signs of low tissue oxygen toxin due to anaemia.
• Plasma

  A component of blood
• Whole blood Centrifuged

  Separates RBCs from plasma
• Plasma separated off

  Into one of the attached satellite bags
• Fresh frozen plasma

  If processed and frozen within 24hr of collection, has a shelf life of 1 year
• Frozen plasma

  If frozen >24 hours after collection or is FFP after 1 year, has a shelf life of an additional 4 years
• Cryoprecipitate

  Derived from fresh frozen plasma - shelf life of 1 year.

  Plasma fraction separated from fresh frozen plasma with controlled thawing and centrifugation.

  Concentrated product labile clotting factors:

  • Fibrinogen
  • Factor VIII
  • Von Willebrands factors.
• Cryosupernatant

  Derived from fresh frozen plasma with a shelf life of 1 year.

  Remain fraction from the FFP after the cryoprecipitate has been produced.

  Contains plasma proteins including albumin and vitamin K dependant clotting factors II, VII, IX and X.
• What to transfuse?

  Replace what is lacking.

  Relies on our ability to assess suitability of the use of each of the products.

  Considerations:

  • Some products contain more than you need - risks?
  • Some may contain less - risks?
  • Whole blood from a donor is generally cheaper - but what if multiple transfusion are required?
  • Remember the benefits of transfusion must outweigh the risks.
• What is Autologous transfusion?

  Recycling the animals own blood back into it. For example if bleeding into abdomen remove the blood from there and transfuse it back into the animal. Can not do if possible neoplastic mass causing bleeding as blood could have metastases in it and could spread.
• Benefits of autologous transfusion

  Reduces potential exposure to allogenic blood, reduces the risk of (new) infectious diseases, reduced the chance of transfusion reactions, immediately available.
• Canine blood collections

  Collection sessions run regularly by the pet blood bank or can be collected in practice.Peform full physical health check.

  Haemotology and biochemsitry (minimum PCV/TS).

  Blood typing.
• Donor criteria for canine blood donation

  Fit and healthy,

  1-8 years old.

  >25kg

  Good temperament

  Never travelled abroad

  Vaccinated

  Not on any medication.
• Equipment required for canine blood collection

  450ml blood collection bag with CPD/CPD-A.

  Electronic weigh scales

  Macoclam—P

  Tube stripper.
• How to take canine blood for transfusion?

  2 assistants to hold the dog.

  Lateral recumbency on the table.

  Venipuncture in jugular vein (generally the right jugular).

  Release clamp and blood should flow to the bag easily.

  Regulary rock the collection bag to mix with anticoagulant.

  Clamp line.

  Remove needle and apply neck bandage.

  Use the tube stripper to strip the blood in the line into the bag.

  Check demeanour, HR, MM quality and pulse quality.

  Offer small amount of food and water.
• Feline blood collection - donor criteria

  Healthy

  1-8 yeas old.

  >4kg lean bodyweight.

  Preferably indoor cat.
• Equipment needed for feline blood collection

  60ml luer tip syringe.

  Three way tap

  Source of CDPA-1/CDP

  Macoclamp-P.
• How to take blood from cat for transfusion

  Calculate amount of blood to be drawn (11-13ml/kg).

  Add required amount of CDP/CDPA-1 to the 60ml syringe.

  Lateral/dorsal recumbency.

  Assistant raises the jugular vein, then Peform jugular venepuncture and lightly pull on 60ml syringe.

  Blood should flow freely.

  When have desired amount, remove needle, apply pressure to neck for 2 minutes then apply neck bandage.

  Monitor HR, MM and can administer isotonic fluids after.
• Equipment needed for administering a blood product

  Unit to be administered.

  Zip lock bag.

  Tray/bowl to use as water bath (warm product to 37C).

  Thermometer.

  Filtered giving set (for smaller cats and dogs: Hemo-Nate filter).

  IV catheter (largest gauge possible for the patient).
• Clinical presentations or transfusion reactions

  Increase in temperature

  Change in the respiration/ heart rate.

  Change in mucous membrane colour.

  Visible oedema.

  GI signs.

  More severe signs also possible.
• What are the types of immunological transfusion reactions?

  Heamolytic

  Non-haemolytic
• What are the types of non-immunological transfusion reactions?

  Circulatory overload.

  Bacterial contamination.

  Hypothermia

  Citrate toxicity

  Dilutional coagulopahty

  Hyperammonaemia and acidosis

  Disease transmission
• Acute haemolytic transfusion reactions

  Blood type incompatibility.

  Class II (antigen-antibody) hypersensitivity reaction - acute intravascular haemolysis.

  Uncommon (particularly in horses and dogs).

  Type B cat administered type A or AB blood.

  DEA-1 -ve dogs sensitise fo DEA 1 and repeated exposure.

  Clinical signs may include: fever, tachycardia, dyspnoea, muscle tremors, V+, weakness, collapse, haemoglobinuria, shock death.

  Transfusion should be stopped immediately.
• Delayed haemolytic transfusion reaction

  Extravascular haemolysis.

  3-21 days post transfusion.

  May occur in dogs administer incompatible blood on first transfusion.

  Reduced lifespan of donated erythrocytes (post-transfusion PCV rapidly declines).

  Hyperbilirubinaemia +/- bilirubinuria.

  Specific treatment generally not required.
• Febrile non-haemolytic transfusion reactions

  Acute PLT/WBC hypersensitivity.

  Most common TR with whole blood.

  Mild and transient fever.

  Leukoreduction can help minimise this.