The feline AB blood group system and its importance in transfusion medicine

Production of Feline Universal Erythrocytes with Methoxy Polyethylene Glycol

Blood group mismatch in veterinary medicine is a significant problem in blood transfusion, sometimes leading to severe transfusion reactions and even patient death. Blood groups vary from species to species and there are three known blood groups in cats: A, B and AB. While A-type cats are most common, there is a shortage of feline B-type blood groups in cats. By using methoxy polyethylene glycol (mPEG) to protect antigenic epitopes on red blood cells (RBCs), we aimed to find the optimal conditions for the production of feline universal RBCs. The surfaces of feline A-type RBCs were treated with mPEG at various molecular weights and concentrations. Agglutination tests showed that the coating of feline A-type RBCs with mPEG of 20 kDa and 2 mM blocked hemagglutination to feline anti-A alloantibodies over 8 h. While no differences in RBC size and shape between intact and mPEG-treated RBCs were seen, coating RBCs with mPEG inhibited the binding of feline anti-A alloantibodies. Furthermore, the mPEG-treated RBCs did not cause spontaneous hemolysis or osmotic fragility, compared to control RBCs. According to a monocyte monolayer assay, mPEG treatment significantly reduced feline anti-A antibody-mediated phagocystosis of RBCs. These results confirm the potential of using activated mPEG on feline A-type RBC to create universal erythrocytes for transfusion to B-type cats.

Retrospective study of canine blood xenotransfusion compared with type-matched feline blood allotransfusion to cats: indications, effectiveness, limitations and adverse effects

OBJECTIVES

Xenotransfusion is the transfusion of blood from one species to another. With varying availability of allogenic feline blood (AFB) and in emergency conditions, circumstances occur when canine blood is transfused to cats. This study aimed to characterise the indications, effectiveness, limitations, and acute and late transfusion-related adverse effects of canine blood xenotransfusion compared with matched AFB to anaemic cats, and their survival and longer-term outcome.

METHODS

This retrospective study (2013-2020) examined cats receiving canine blood xenotransfusions or AFB.

RESULTS

The study included 311 cats (xenotransfusion [X-group], n = 105; allotransfusion [A-group], n = 206). Xenotransfusion was more frequent among cats sustaining haemorrhage than in those with haemolysis (P <0.01) or hypoproliferative anaemia (P <0.001). Financial constraints were the most common reason to elect xenotransfusion (49%). The post-transfusion mean packed cell volume was higher (P <0.001) in the X-group (22%) compared with the A-group (18%), and also higher (P <0.001) at 48-96 h post-transfusion (23% vs 18%, respectively). Transfusion-related adverse effects (TRAEs) were more frequent (P = 0.001) in the X-group (37.1%) compared with the A-group (19.4%), as were delayed haemolytic transfusion reactions (85% vs 42.5%, respectively; P <0.001). Acute transfusion reactions (ATRs) were more frequent (P <0.001) in the A-group (60%) compared with the X-group (20%). TRAEs were unassociated with survival to discharge. The survival to discharge rate of the X-group (55%) was lower (P = 0.007) than in the A-group (73%), while post-discharge survival rates to 30 days of cats surviving to discharge were 90% and 88%, respectively (P = 0.85).

CONCLUSIONS AND RELEVANCE

Canine blood xenotransfusions to cats might save lives in emergency conditions when AFB is unavailable or blood typing is infeasible. The survival to discharge rate of the X-group was lower than that of the A-group. The longer-term survival rate of cats administered xenotransfusions and surviving to discharge from the hospital was good.

Wild Felids Blood Group System

Wild felids and domestic cats share the AB blood group. However, there have been few studies regarding the characterization and prevalence of the different blood types in wild animals. The erythrocyte membrane glycolipids of the wild cats correspond to the major disialoganglioside patterns observed in domestic cats. Like in domestic cats, type A blood seems to be the most common, although wild felid species seem to exhibit one single blood type. Of the species studied, the wild domestic cats, and the Panthera and ocelot lineages, all had type A blood; the Puma lineage showed almost exclusively type B blood. The prevalence of wild felids blood types show that there seems to be variation between species, but not within species, and no evidence of geographical variation has yet been found, showing apparently no genetic variability. The presence of alloantibodies has also been demonstrated, so the risk of life-threatening transfusion reactions due to mismatched transfusions and neonatal isoerythrolysis is a possibility. Like in other species, the recognition of wild felids blood groups is clinically relevant, as it can also be important in establishing phylogenetic relationships within the Felidae family. We will review the current knowledge on this topic and give insights into the wild felids blood groups potential for zoo transfusion medicine and phylogenetic studies in order to help support reintroduction projects and to preserve genetic diversity.

Identification of 5 novel feline erythrocyte antigens based on the presence of naturally occurring alloantibodies

Background

Since the discovery of the Mik antigen, several studies have described blood incompatibilities unrelated to the AB system in cats.

Objective

To estimate the prevalence of cats with non‐AB incompatibilities associated with naturally occurring alloantibodies (NOAb), and to begin mapping the corresponding feline erythrocyte antigens (FEA).

Animals

Two hundred and fifty‐eight type A cats.

Methods

Prospectively, cats were evaluated for the presence of NOAb by crossmatching in groups of 4‐6 cats. When NOAb were detected in a cat, its plasma was used as reagent to assess for the presence of the corresponding FEA in all cats included thereafter, and agreement observed between results of this extensive blood typing was evaluated.

Results

The chance of detecting incompatibilities by randomly crossmatching 2 cats was 3.9%, which resulted in at least 7% of type A cats having NOAb. Blood typing and agreement analyses performed with 7 newly detected NOAb allowed the identification of 5 presumably distinct FEA. Feline erythrocyte antigens 1 and 5 were most frequent with prevalence of 84% and 96%, respectively. Only FEA 1‐negative status was associated with a higher risk of presenting NOAb; with 16.7% of 42 FEA 1‐negative cats having NOAb compared to 5.1% of 216 FEA 1‐positive cats.

Conclusions and Clinical Importance

This study represents a first step of FEA identification outside the AB system. Because of its prevalence and association with NOAb, FEA 1 might correspond to the Mik antigen.

Exploration of risk factors for non-survival and for transfusion-associated complications in cats receiving red cell transfusions: 450 cases (2009 to 2017)

OBJECTIVES

To describe red blood cell transfusion practices and short-term outcomes in anaemic cats. To determine clinical variables associated with non-survival and transfusion-related complications.

MATERIAL AND METHODS

In this retrospective study, blood bank records from the Ontario Veterinary College Health Science Centre (OVC-HSC) were reviewed to identify cats that received packed red blood cells or whole blood from 2009 to 2017. We extracted cause of anaemia, history of previous transfusion, pre- and post-transfusion packed cell volume, pre-transfusion compatibility testing, volume and dose of blood product, age of red blood cell unit, transfusion-associated complications and patient survival.

RESULTS

A total of 450 transfusion events were recorded in 267 cats. Blood loss was the most common indication for blood transfusion (44.9%), followed by ineffective erythropoiesis (37.5%) and red blood cell destruction (22.5%). Transfusion-associated complications occurred in 10.2% events and there was a 20.2% mortality after transfusion. Mean increase in packed cell volume 24-hours after transfusion was greater in cats undergoing major cross-match testing before transfusion (7.2%) versus those that did not (4.0%). Non-survival was associated with higher packed cell volume before transfusion, low patient body temperature before transfusion, anaemia due to blood loss and number of transfusions administered. Older age of transfused blood units was associated with non-survival and transfusion-related complications.

CLINICAL IMPORTANCE

This study was observational and so our analyses were exploratory, but suggest that major cross-match before transfusion tended to have greater transfusion efficacy and transfusion of older blood products might have detrimental effects on survival.

Cryopreservation of feline red blood cells in liquid nitrogen using glycerol and hydroxyethyl starch

OBJECTIVES

The objective of this study was to evaluate the techniques and short-term effects of cryopreservation of feline red blood cells (RBCs) in liquid nitrogen using glycerol or hydroxyethyl starch (HES) as a cryoprotectant.

METHODS

Feline RBCs were manually mixed with either 20% glycerol or 12.5% HES and frozen for 24 h in liquid nitrogen. The samples were thawed and glycerolized samples were manually washed. Success of the freeze/thaw process was determined by recovery rate of RBCs and evaluation of morphological changes using scanning electron microscopy (SEM). A unit of canine packed RBCs was also subjected to the same methodology to evaluate the cryopreservation handling technique.

RESULTS

Feline RBCs preserved with 20% glycerol had a high recovery rate (94.23 ± 1.25%) immediately after thawing. However, the majority of the cells were lost during the washing process, with a final packed cell volume of <1%. A recovery rate was unable to be assessed for samples preserved with HES owing to the high viscosity of the mixture. SEM revealed significant morphological changes after glycerol was added to the feline RBCs. Although these morphological changes were partially reversed after thawing, the majority of the RBCs were lost during the washing process. Minimal morphological changes were noted in the HES sample. Similar results were noted with the canine RBCs.

CONCLUSIONS AND RELEVANCE

The described manual technique for cryopreservation using glycerol was not able to successfully preserve feline or canine RBCs. In the present study, it was difficult to make conclusions about the efficacy of HES. Further studies evaluating HES as a cryoprotectant are warranted.

Sistema de grupos sanguíneos AB em felídeos neotropicais e compatibilidade com gatos domésticos

RESUMO O principal sistema de grupos sanguíneos reconhecido para gatos é o AB. Os felinos apresentam anticorpos naturais contra o antígeno do tipo sanguíneo a que não pertencem, o que torna os testes de compatibilidade e as tipagens sanguíneas importantes na prevenção de reações transfusionais. O objetivo deste estudo foi realizar a tipagem sanguínea de oito gatos-mouriscos (Puma yagouaroundi), oito jaguatiricas (Leopardus pardalis), sete gatos-palheiros (Leopardus colocolo), sete gatos domésticos (Felis catus) da raça Persa e oito gatos domésticos sem raça definida (SRD), bem como realizar testes de compatibilidade entre os tipos sanguíneos iguais das diferentes espécies, para avaliar a possibilidade de transfusões interespecíficas. A técnica empregada para a tipagem foi a hemaglutinação em tubos de ensaio. A ocorrência do tipo sanguíneo tipo A foi de 100% entre as jaguatiricas, os gatos-palheiros e os gatos Persas e de 85,72% entre os gatos SRD. A ocorrência do tipo B foi de 100% nos gatos-mouriscos e de 14,28% nos gatos SRD. Considerando os testes de compatibilidade sanguínea, 87,5% (n=4) das jaguatiricas foram incompatíveis com os gatos domésticos, 100% (n= 6) dos gatos-palheiros foram compatíveis com os gatos domésticos e 100% (n= 4) dos gatos-mouriscos foram incompatíveis com os gatos domésticos do tipo B.

FREQUÊNCIAS DOS TIPOS SANGUÍNEOS E TÍTULOS DOS ALOANTICORPOS EM FELINOS DOMÉSTICOS

Resumo A área da hemoterapia necessita de testes de compatibilidade sanguínea confiáveis, como a tipagem sanguínea, para se evitarem possíveis reações transfusionais, mas em felinos é também importante para se evitar a isoeritrólise neonatal. Transfusões sanguíneas realizadas entre felinos doadores e receptores que não possuem compatibilidade sanguínea podem refletir em reação transfusional aguda, particularmente severa quando o sangue tipo A é transfundido em um gato tipo B, pois geralmente este último possui altos níveis de aloanticorpos de ocorrência natural. Portanto, o conhecimento da frequência dos tipos sanguíneos da população de gatos de uma região pode auxiliar na determinação dos riscos de reações transfusionais e de ocorrência de isoeritrólise neonatal. Tais riscos podem ser prevenidos com a tipagem sanguínea em casos de transfusão. Foram coletadas 100 amostras sanguíneas de felinos para a realização da tipagem sanguínea com plasmas reagentes anti-A e anti-B conhecidas e titulações de aloanticorpos anti-A e anti-B dos plasmas armazenados. A distribuição das frequências dos grupos sanguíneos foi 96% de felinos com tipo sanguíneo A e 4% de felinos com tipo sanguíneo B, não sendo encontrado na amostra populacional de felino tipo AB. Há um grande risco de reação adversa através da transfusão sanguínea randomizada entre felinos não tipados previamente.

Feline blood genotyping versus phenotyping, and detection of non-AB blood type incompatibilities in UK cats

OBJECTIVES

The aim of this study was to determine the agreement between AB blood phenotyping and genotyping and determine whether non-AB blood type incompatibilities exist in UK cats.

METHODS

Blood samples underwent phenotyping (A, B or AB) using microplate agglutination, and genotyping (AA, Ab or bb) using pyrosequencing of a fragment of the cytidine monophospho-N-acetylneuraminic acid hydroxylase gene. Non-AB blood type incompatibilities were investigated by cross-matching against reference blood of the same phenotype.

RESULTS

Of 112 cats tested, 86 (77%) were blood phenotype A, 19 (17%) type B and 7 (6%) type AB. Genotype and initial phenotype agreed in 96% (107 of 112) of cats, but 5 were discordant; these were all B phenotype with either AA (n=2) or Ab (n=3) genotype. Two of the five cats had repeat blood samples tested: one was reclassified as phenotype A; the other remained phenotype B. Two cats had incompatibilities on minor cross-match, but these were attributed to phenotyping errors.

CLINICAL SIGNIFICANCE

Unknown mutation(s) associated with phenotype B, resulting in false AA or Ab genotyping, were evident in a small number of cases in this study. No conclusive evidence for non-AB blood type incompatibilities was found.

Blood groups in the Species Survival Plan®, European endangered species program, and managed in situ populations of bonobo (Pan paniscus), common chimpanzee (Pan troglodytes), gorilla (Gorilla ssp.), and orangutan (Pongo pygmaeus ssp.)

Blood groups of humans and great apes have long been considered similar, although they are not interchangeable between species. In this study, human monoclonal antibody technology was used to assign human ABO blood groups to whole blood samples from great apes housed in North American and European zoos and in situ managed populations, as a practical means to assist blood transfusion situations for these species. From a subset of each of the species (bonobo, common chimpanzee, gorilla, and orangutans), DNA sequence analysis was performed to determine blood group genotype. Bonobo and common chimpanzee populations were predominantly group A, which concurred with historic literature and was confirmed by genotyping. In agreement with historic literature, a smaller number of the common chimpanzees sampled were group O, although this O blood group was more often present in wild-origin animals as compared with zoo-born animals. Gorilla blood groups were inconclusive by monoclonal antibody techniques, and genetic studies were inconsistent with any known human blood group. As the genus and, specifically, the Bornean species, orangutans were identified with all human blood groups, including O, which had not been reported previously. Following this study, it was concluded that blood groups of bonobo, common chimpanzees, and some orangutans can be reliably assessed by human monoclonal antibody technology. However, this technique was not reliable for gorilla or orangutans other than those with blood group A. Even in those species with reliable blood group detection, blood transfusion preparation must include cross-matching to minimize adverse reactions for the patient.

Comparison of gel column agglutination with monoclonal antibodies and card agglutination methods for assessing the feline AB group system and a frequency study of feline blood types in northern Italy

BACKGROUND

A new commercial gel column agglutination system is reported to have high sensitivity in detecting cats with blood type AB.

OBJECTIVES

The aims of this study were to compare gel column agglutination and card agglutination methods for feline blood-typing and to determine the frequency distribution of feline blood types in northern Italy.

METHODS

Blood-typing was performed on 120 cats using both a commercial gel column containing monoclonal antibodies (ID Gel-Test Micro Typing System) and a card agglutination method (RapidVet-H Feline). Results were confirmed with back-typing. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for the 2 methods. A second group of 140 Domestic Shorthair (DSH) cats was blood-typed using the gel column technique to determine the frequency distribution of feline blood types in northern Italy.

RESULTS

The card agglutination method demonstrated poor sensitivity in identification of type-AB cats (61%) and was only 95% specific when identifying type-B cats. The gel column agglutination technique demonstrated 100% sensitivity and specificity for typing all 3 blood types (A, B, and AB). The frequency distribution study of 140 cats demonstrated that 127 (90.7%) cats were type A, 10 (7.1%) were type B, and 3 (2.1%) were type AB.

CONCLUSION

When blood-typing cats of breeds with a relatively high frequency of blood types B and AB, methods that use monoclonal antibodies for detection of blood types B and AB are recommended. Alternatively, blood type can be confirmed by more sensitive supplemental testing, such as back-typing. The high frequency of blood type A in DSH cats in northern Italy was comparable to previously reported frequencies in Italy and world-wide.

Feline blood transfusions: A pinker shade of pale

PRACTICAL RELEVANCE

blood transfusions are a potentially life-saving procedure that are within the reach of most small animal practitioners. Only minimal equipment is required.

PATIENT GROUP

any cat with clinical signs attributable to a reduced red blood cell mass that is affecting oxygen transport (as a result of reduced packed cell volume or acute blood loss) is a potential candidate for a transfusion.

CLINICAL CHALLENGES

although the principles of transfusion medicine are not complicated, there can be fatal consequences if certain steps are omitted.

DIAGNOSTICS

blood typing kits and blood filters are readily available from veterinary wholesalers, laboratories and blood banking services.

EVIDENCE BASE

over the past three decades, a substantial body of clinical research and reports has built up covering feline blood types and transfusion medicine. This article draws on that research to provide clinical guidance aimed at all veterinarians in feline or small animal practice who either currently practise transfusion medicine or plan to do so.

Feline neonatal isoerythrolysis and the importance of feline blood types

Although feline neonatal isoerythrolysis is rare, associated mortality rate is high. It results from mating of type B blood queens with type A or AB blood toms. A comprehensive review on feline blood types and feline neonatal isoerythrolysis physiopathology, clinical features, diagnosis, treatment, and prevention is covered.

Blood types in Bengal cats in the UK

Blood samples from 100 adult Bengal cats from the UK were submitted for assessment of blood type using RapidVet-H Feline blood typing cards (dms Laboratories), with further assessment by standard blood typing in a microtitre plate assay when card typing was inconclusive or revealed blood type B or AB. Ninety-eight cats were found to be type A when assessed using the blood typing cards. One cat initially tested as type AB but was found to be type A on testing a second blood sample using the blood typing cards. One cat initially tested as type B but was found to be type A when a second sample was tested by standard blood typing assay. Finding that 100% of the cats were blood type A is in contrast with previous studies that reported 10 Bengal cats to be type A, four to be type AB and one to be type B.

Frequencies of feline blood types at a referral hospital in the south east of England

OBJECTIVES

To determine the prevalence of blood types in the feline patients and blood donors of the Queen Mother Hospital for Animals (The Royal Veterinary College, London, UK), that were typed between 2000 and 2004.

METHODS

A retrospective study was performed using files of patients and blood donors of the Queen Mother Hospital for Animals seen between January 2000 and November 2004. Commercial blood typing cards were used to determine the blood type.

RESULTS

One hundred and fifty-six cats were included in the study; 51 (32.7 per cent) were pedigree and 105 (67.3 per cent) non-pedigree. Of the 51 pedigree cats, the prevalence of blood types was as follows: type A, 42 (82.4 per cent); type B, seven (13.7 per cent) and type AB, two (3.9 per cent). Of the 105 non-pedigree cats, the prevalence of blood types was as follows: type A, 71 (67.6 per cent); type B 32 (30.5 per cent) and type AB two (1.9 per cent).

CLINICAL SIGNIFICANCE

The prevalence of type B blood in non-pedigree cats is higher than previously suggested and shows high variability within the UK; because of this, blood typing all feline patients, not only the ones of a breed typically known to have higher prevalence of type B blood before transfusion, is absolutely necessary to avoid a fatal transfusion reaction.

Frequencies of blood type A, B and AB in non-pedigree domestic cats in Turkey

OBJECTIVES

To determine the distribution of blood types and to estimate the proportion of matings at risk for neonatal isoerythrolysis in non-pedigree domestic cats.

METHODS

The present survey determined the frequency of blood types in 301 cats from four distinct regions of Turkey. Ethylenediaminetetraacetic acid-anticoagulated blood samples were typed by simple tube and slide agglutination assays. Serum obtained from type B cats and an anti-B solution, prepared with Triticum vulgaris, were used to determine type A and type B blood, respectively.

RESULTS

Of the 301 cats typed, 220 had type A blood, 74 had type B and seven had type AB. There was a significant difference (P<0.01) between the locations of the cats, with fewer type B cats in the eastern than in the western parts of Turkey. Risk for the development of neonatal isoerythrolysis due to A-B mismatch was estimated to be 18.6 per cent.

CLINICAL SIGNIFICANCE

The overall type B frequency in Turkish domestic cats is high. Thus, untyped transfusions in these cats carry a high risk of life-threatening acute haemolytic transfusion reactions and neonatal isoerythrolysis. It is therefore strongly recommended that blood typing be performed before breeding or transfusing in order to minimise blood type incompatibility risks.

Titres of naturally occurring alloantibodies against feline blood group antigens in Turkish Van cats

Seventy-eight Turkish Van cats were examined for alloantibody titres, of which 42.3 per cent had type A blood and 57.7 per cent had type B blood. No type AB cats were found. All type B cats (n = 45) showed gross evidence of agglutinating anti-A antibody, with titres ranging from 2 to 256. Sixty-seven per cent of type B cats had anti-A antibody in their plasma, with titres ranging from 8 to 32. However, 13 per cent of type B cats had plasma alloantibody titres of less than 8 and 20 per cent had titres that were higher than 32. A total of 33 type A cats were also tested for anti-B alloantibody titres in their plasma. Among the type A plasma, gross agglutination at titres of 2 and greater than 2 were determined in 24 per cent and 36 per cent of samples, respectively. Microscopic agglutination was seen in an additional 18 per cent of plasma samples. There was no significant association between gender and plasma alloantibody titres of cats (P > 0.05).

Whole blood transfusions in 91 cats: a clinical evaluation

This survey assessed the feline transfusion practices at the University of Berlin from 1998 to 2001 in regard to patient population, indications, efficacy, and transfusion reactions. Blood was obtained from seven healthy in-house donors and 127 mostly indoor client-owned pet cats. Over a 3-year period 91 cats were transfused with blood type compatible blood. The blood was fresh (within 8 h of collection) or stored no longer than 15 days. Transfusions were required because of blood loss anaemia (n=40), haemolytic anaemia (n=13), ineffective erythropoiesis (n=35), hypoproteinaemia (n=2) or coagulopathy (n=2). The anaemic cats had a pretransfusion haematocrit of 5-20% (m [median]=13), and received one to six transfusions (m=1). The survival rates of the anaemic cats at 1 and 10 days after transfusion were 84 and 64%, respectively. None of the deaths appeared to be related to transfusion reactions. The major crossmatch, undertaken before 117 transfusions, was incompatible for eight cats. All except for one had previously been transfused. Lysis of transfused cells in six cases resulted in a less than expected haematocrit rise and an increase in serum bilirubin. Transient mild transfusion reactions were only noted in two cats during the second or third transfusion. In conclusion, with proper donor selection and appropriate compatibility screening, blood transfusions are well tolerated, appear effective, and may increase chances of survival.