Feline blood transfusions practical guidelines for vets

1 Feline blood transfusions practical guidelines for vets This Practice Indications Feline blood types and Pointers' article Severe anaemia blood -type reactions from the ISFM Severe anaemia with associated clini- Cats have three main blood types, A, B. is complemented cal signs particularly if anaemia has and AB, based on the blood type developed acutely, with little time for antigens they possess. Other blood by practical compensatory mechanisms to develop types (eg, mik) have been reported guidelines for is the principal reason why a blood in the literature but are not routinely vet nurses, and tested for. The presence of other blood transfusion may be performed in a cat. an information If there is concurrent hypovolaemia types may, however, may be a reason sheet for owners (eg, blood loss), whole blood will be for reduced survival of transfused on offering their most appropriate.

2 If the cat is normo- cells in cats of the same (A or B) blood cat as a blood volaemic (eg, haemolysis), packed red type. donor. Together blood cells (RBCs) are most appropri- the series is ate, although not readily available so intended to whole blood is usually given. In the UK most improve the non-pedigree cats are practice of blood Provision of clotting factors type A, with a smaller In some cats, a requirement for clotting factors contained In contrast to transfusions percentage of type B and type within fresh plasma may warrant a transfusion; consideration dogs, cats pos- and, in turn, the sess naturally AB, although the prevalence of can be given to separating red cells/plasma for an individual welfare of the patient, but this is rarely performed in the UK.

3 Note that occurring allo- type B appears to be increasing cats involved. among non-pedigrees. Type B can clotting factors degrade relatively quickly even if blood / antibodies reac- be very prevalent (approaching plasma is refrigerated. Furthermore, transfusions are not a tive against the 50%) in some pedigree breeds, good source of platelets, although whole blood does contain blood -type anti- especially the British Shorthair, some functional platelets, so may be of some benefit in gen that they Ragdoll, Birman and Rex breeds. thrombocytopenic patients. are lacking: Type B cats are also commonly >70% of type encountered among Persians, A cats have anti- Somalis, Abyssinians and B alloantibodies, Scottish Folds. Siamese mostly at low titres;. Weighing up the risks versus benefits All type B cats cats are almost invariably type A.

4 There are potential risks to the donor cat associated with have anti-A alloantibod- blood collection that must be carefully weighed up against the ies, often at high titres;. potential gain for the recipient cat. In all cases it is important Type AB cats are not to be certain that a blood transfusion thought to have alloantibodies to is definitely the most either type A or type B antigens. appropriate treatment. These alloantibodies are responsible for the two main Not every anaemic cat The potential gain to the blood -type reactions seen in cats: haemolysis due to will need a blood recipient cat must outweigh incompatible blood transfusion reactions, even with a first transfusion and so the the risk to the donor. transfusion, and neonatal isoerythrolysis.

5 Incompatible blood cat's condition must be fully transfusion reactions can be fatal in type B cats given type assessed and every treatment A blood , as the recipient's anti-A alloantibodies rapidly option considered. If the cat's anaemia is regenerative it may haemolyse the donor type A RBCs. In type A cats given type be that supportive treatment is adequate for a short period B blood , the transfusion reaction is unlikely to be fatal, but of time while the patient replaces its own RBCs. blood the transfused cells will be extremely short-lived. Neonatal substitutes such as Oxyglobin (OPK Biotech) may also be isoerythrolysis can cause kitten mortality and fading kitten appropriate. The impact of diagnostic investigations, and the syndrome and typically arises when a type B queen (having cause of the anaemia, need to be considered too; in a cat with mated with a type A tom) has type A kittens which ingest anti- a terminal illness (eg, neoplasia, FeLV) the potential benefit of A alloantibodies in the first 24 hours of life via their mother's a blood transfusion may not outweigh the risk to the donor.

6 Colostrum. These anti-A alloantibodies rapidly destroy the kitten's type A RBCs and can cause death. practice p o i n t e r s clinical advice from the International Society of Feline Medicine 2 p o i n t e r s Vet checklist prior to collecting blood from a donor Which type to give? Type A cats must only receive type A blood Checked donor eligibility . Type B cats must only receive type B blood Talked through owner information sheet and owner signed . Type AB cats should receive type AB blood , but when consent form not available type A blood is the second choice blood typed . Ensured not donated blood in the past month . Choosing a blood donor Full history and physical examination (including weight) . The following are prerequisites for a blood donor: performed, with no findings of concern Large (>4 kg) and non-obese.

7 Calm temperament; blood pressure checked on day of donation . Aged 1 to 8 years (ideally 1 to 5 years); Routine haematology and biochemistry confirmed to be . Most importantly, healthy (indoor, fully vaccinated cats are within normal limits, at least within the past 6 months but as ideal) and clinically well. close to the time of donating blood as possible In practice, this requires a number of (initial and ongoing) Confirmed Haemoplasma-negative as close to the time . assessments: of donating blood as possible Comprehensive clinical examinations should be Negative FeLV/FIV ELISA on day of donation . performed, and a complete donor history collected;. PCV determined on day of donation . Haematology (complete blood count) and biochemistry (urea, creatinine, total protein/albumin/globulin, ALT, ALP, blood glucose, Na, K, Cl) should be confirmed to be normal.

8 The cat should be screened for bloodborne infectious A diagnostic DNA PCR test, performed on blood or diseases (FeLV-, FIV- and Haemoplasma-negative essential; buccal swabs, is available in the US ( Bartonella screening) as close to the time of donation as ) that can differentiate type B from type possible. Haemoplasma testing may be omitted in an emer- A or AB cats (but cannot determine if a cat is type A or AB). gency situation, but owners should be made aware of this if This may be most appropriate for breeders in the selection of testing is not performed; mating pairs to avoid the risk of neonatal isoerythrolysis. This Packed cell volume (PCV) of the donor should be deter- test has not been validated in all breeds, however. mined before each donation and be 35%.

9 The donor's blood pressure should ideally be checked Cross-matching before each donation to ensure this is normal (120 180 Cross-matching may be performed in addition to blood typ- mmHg). Occult heart disease and other conditions can be ing if previous transfusions have been given (>5 days earlier). associated with low blood pressure that is exacerbated by or if a non-A/B blood group system incompatibility is sus- sedation and blood donation; pected, provided both sufficient time and blood is available. Echocardiography should ideally also be performed in all The major cross-match tests for alloantibodies in the cats prior to donation, to assess for occult heart disease. recipient's serum/plasma against donor RBCs. An incompat- ible major cross-match can result in an acute haemolytic blood typing transfusion reaction, where donor erythrocytes are destroyed donors and recipients must be blood typed before transfu- by alloantibodies in the recipient's plasma.

10 Sions. A number of methods are available that can type the The minor cross-match tests for alloantibodies in the cat as being A, B or AB. donor's serum/plasma against recipient RBCs. A minor EDTA blood samples can be submitted to veterinary cross-match incompatibility is less likely to cause a trans- laboratories (eg, at the Universities of Bristol and Glasgow). fusion reaction because the volume of donor plasma is small Various in-house kits are available, allowing immediate and becomes markedly diluted in the recipient. results. Examples include: The cross-match procedure, described below, is relatively In-house cards (Rapid Vet-H). These use a small quantity complex; where possible it should be performed by some- of EDTA blood and the result is based on visualisation of an one with experience of doing this.