Download blood trAnsfusions in cAts- froM tyPing, cross MAtcHing, donor

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Blood transfusions in cats- from ­typing,
cross matching, donor selection,
­collection and administration
Lindsey Dodd RVN BSc
(Hons) VPAC
Introduction
Transfusion of blood and blood products is often required in an emergency situation
and when prepared and administrated correctly, can be a life saving procedure. Most
frequently blood is required for patients that have occurred blood loss and are anaemic
due to haemorrhage. Administration of whole blood will replace blood volume and
assist with stabilisation. However blood transfusion comes with risks to both recipient
and donor and the risks associated should be weighed before collection of blood from
the donor takes place.
Feline blood types; the AB blood group system
Feline erythrocyte antigens (FEA)
• transfusion relevant blood types
• A, B and AB (positive or negative for the antigen)
• AB most antigenic
• no ‘universal’ donor type; vital to determine recipient and donor blood type prior to
any transfusion
• cats carry naturally occurring alloantibodies reactive to the blood type antigens that
they do not possess
• MiK is a relatively newly recognised feline blood type however unlike A, B and AB
blood types it is not routinely tested for
Natural occurring alloantibodies
It is vital that a cat receives blood from a donor of the same blood type; A blood to the A
cat and B blood to the B cat. When treating a type AB cat it becomes more complicated.
As blood type AB cats are rare in most countries it is often difficult to find another AB
donor. Cats carry naturally occurring alloantibodies to the blood type that they are not.
Giving type A blood to type B cat can have fatal consequences as often blood type B
cats will carry a high titre of anti A alloantibodies. A smaller proportion of blood type A
Abstracts | European Veterinary Conference Voorjaarsdagen 2013
cats will generally carry lower titres of anti B alloantibodies. Therefore if type B blood is
transfused to a type A cat transfusion reaction is less likely to be fatal however the transfused blood will have a very short half life. It is thought that type AB cats don’t carry
alloantibodies for A or B so can either receive type AB blood or can be safely transfused
with type A and B blood however type AB cats can only donate to type AB cats.
Due to naturally occurring alloantibodies to the blood type that they are not it is vital to
blood type all cats receiving blood and donating blood for transfusion. Gold standard
preparation would be to perform a cross match prior to transfusion to establish suitability of the transfusion to the recipient due to the potential presents of other less
researched blood group systems; such as Mik. Cats are either positive or negative to
Mik. Currently there is no point of care assessment method for Mik however incompatibilities will be shown on cross match between recipient and donor blood.
Compatibility testing
Blood typing
By blood typing both recipient and donor, acute and fatal and delayed transfusion reactions can be avoided. There are several point of care assessment tools which are commercially available; FEA blood typing cards that indicate type by agglutination in the
relevant blood type test window. As this test card relies on the visualisation of agglutination it is important to check first for patient auto-agglutination. Another testing kit
exists similar to a pregnancy testing stick. Unlike the card format this test indicates
blood type via a result line alongside the corresponding blood type. Both tests require a
small sample of patient whole blood and take only a few minutes to run. The predominant blood type is type A; most domestic shorthaired cats are blood type A whereas
pedigree breeds such as the Dexon Rex and British Shorthair have been reported to be
commonly blood type B.
Cross matching
After ascertaining the patient’s blood type and selecting an appropriate donor of the
same blood type it is best practice to perform a cross match. However the clinician may
opt to administer the blood transfusion without cross matching if the risk of waiting for
the cross match result will impact negatively on the donor; for example the severely
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acutely anaemic cat.
A cross match assesses for potential transfusion reactions before administrating the
blood product to the patient and therefore highlights the potential risk of reaction and
can assist the clinician in donor selection.
Cross matching- examining for agglutination and haemolysis
Centrifuge both recipient and donor blood and separate cells from plasma
• major
1 drop donor red blood cells – 2 drops recipient serum and/or plasma
• minor
1 drop recipient red blood cells – 2 drops donor serum and/or plasma
• Controls
donor control (donor RBCs and donor serum or plasma)
Recipient control (recipient RBCs and recipient serum or plasma)
In feline transfusion medicine, unlike canine transfusion medicine, it is rare to give
blood component therapies; a unit of pack red cells, or a unit of fresh frozen plasma etc.
Often the feline recipient will receive a unit of whole blood and therefore require both
major and minor crossmatch. However if a unit of packed red cells only was to be transfused only a major crossmatch would be necessary and if a unit of plasma was to be
transfused only a minor crossmatch would be required.
Compatibility testing prior to transfusion maximises the effect of blood administration
and reduces the risk of transfusion reaction and is the gold standard preparation for
feline transfusion medicine. However, it should be noted that a compatible major and
minor crossmatch will not eradicate the risk of transfusion reaction; reaction to donor
leukocytes or plasma proteins and delayed transfusion reaction; normal red blood cell
survival. It is paramount that all patients receiving blood products are be monitored
closely.
Donor selection
Feline
• age- 1-10 years old, preferably 1-8years old
• at least 4kg, preferably 4.5kg (lean body weight)
Abstracts | European Veterinary Conference Voorjaarsdagen 2013
• healthy without disease; care with clinically stable felines with significant heart disease; hypertrophic cardiomyopathy (echocardiogram prior to blood donation?)
• good temperament- behaviourally compatible- consider donor welfare
• preferably an indoor cat (care multi cat households)
• breed- DSH mostly A
• normal PCV- 35-50%
• normal TP- 50-70g/l
A good blood donor
• fully vaccinated (no donation 14 days post vaccination)
• flea and wormed
• full clinical examination
• full history
• no previous blood transfusions
• screened for infectious disease, blood type and general health status- biochemistry
and haematology
• no travel abroad
• owner of the donor- realistic, understand the procedure (sedation) flexible, contactable, OOHs?
• keep a record of all the information
Donation process
Felines
• place an i/v catheter
• sedation required; typically Ketamine and Midazolam
• blood volume- 15-20% maximum- 11-12ml/kg
• collection time 5-8mins
After donation;
• monitor sedation- Temperature, Pulse, Respiration, mucous membrane colour, capillary refill time, blood pressure
• reverse sedation if appropriate
• close monitoring post blood donation; blood pressure, rate of intravenous fluid
therapy.
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• replace blood taken with crystalloids
• Feed!
Administration of blood transfusion
Vital considerations! Heart conditions, rate,
Blood giving set; filter, preparation; aseptic technique, care with warming blood products
Giving and monitoring the blood transfusion
General protocol
• start at low rate; 0.25ml/kg/hr for the first 30 minutes
• bedside monitoring q15 minutes checks for the first 30 minutes
• increase to 5-10ml/kg/hr (normovoleamic)
• q15-30min checks
• then increase to 30-60min checks if the patient is stable and showing no sign of transfusion reaction or fluid overload
• infuse blood within 4 hours
Transfusion rates;
In an emergency life and death situation- as fast as possible?
Care must be taken with administration to feline patients as overloading the patient’s
circulation can lead to congestive heart failure.
Monitor
• temperature
• pulse/heart rate
• respiration rate
• urticaria
• erythema
• vomiting
• pyrexia
• collapse
• tremours
• seizures
• dyspnoea
• tachypnoea
Abstracts | European Veterinary Conference Voorjaarsdagen 2013
• coughing
• tachycardia
• bradycardia
If a reaction occurs
• stop the transfusion- speak to the case clinician
• intravenous fluid therapy- Crystalloids
• antihistamines
• and corticosteriods
Transfusion reaction
- Immunological or non-immunological reactions
- Acute or delayed reactions
Acute immunological reaction
• Severe and occasionally fatal
• Treat like an anaphylactic reaction
- Red blood cell incompatibility reactions
- Reactions to plasma proteins
- Reactions to white blood cells and platelets
Acute non-immunological reaction
• Hypocalcaemia- citrate in the anticoagulant
• Embolism- clots within the transfusion product
• Circulatory overload- in the normovoleamic patient- due to rapid administration of
fluid
• Bacterial infection- contaminated blood
• Haemolysis- damaged red cells- physical or thermal damage
Delayed Immunological
Early destruction of transfusion due to the recipient developing antibodies to the cells
transfused- haemoglobinuria
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Delayed Non-immunological
Generally infections (often viral)
E.g. FIV, FeLV, Mycoplasma haemofelis
Points to remember
• Pre testing- blood typing and cross match reduces the risk of transfusion reaction
• Pre testing vital in cats and second transfusions in dogs
• Keep willing donors on file and check donors regularly- retire donors when
appropriate
References
on request
Abstracts | European Veterinary Conference Voorjaarsdagen 2013
www.voorjaarsdagen.eu