Transfusion reactions in cats due to AB blood group incompatibility

Discordance between ABC blood phenotype and genotype in a domestic short-haired cat

An adult domestic short-haired feline leukemia virus-infected cat was referred for kidney failure and worsening anemia requiring transfusions. ABC blood typing was performed with an immunochromatographic strip assay at different occasions. Gel column systems were used for the major and minor crossmatching tests, and anti-A and anti-B titers were determined. No discrete A or B bands appeared on the immunochromatographic strips at any time point for the recipient cat. The recipient's plasma agglutinated RBCs from tested type A and B cats. The recipient's RBCs appeared compatible with plasma from 1 type A and 2 B donors, and incompatible with plasma from another type A cat. Genotyping of recipient blood revealed a single homozygous c.179G>T CMAH variant predicting a blood type B. These studies suggest an unusual weak type B or missing all ABC antigens. The latter resembles the exceedingly rare Bombay phenotype in the human ABO blood group system.

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.

Phenotypic and Genetic Characterization for Incompatible Cross-Match Cases in the Feline AB Blood Group System

The feline AB blood group system (blood types A, B, and AB) encoding the cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) gene is the most significant in transfusion medicine and hemolysis of the newborn for cats. Blood typing and cross-matching in pre-transfusion testing are crucial to determining blood compatibility and thus prevent hemolytic transfusion reactions. We here performed serological and genetic investigations to characterize blood samples from cats with discordant results for card agglutination (CARD) and the alloantibody agglutination test for blood typing in two cats (subjects K and R). Subject K showed incompatible cross-matching in pre-transfusion testing. Red blood cells from subjects K and R determined blood type B from the CARD method showed blood type AB by alloanti-A and alloanti-B antibodies in agglutination testing. Genomic DNA sequencing of the coding region (exons 1a to 14) for the cat CMAH gene showed that subject K had four mutations with heterozygosity at c.139C>T, c.179G>T, c.327A>C, and c.364C>T. Similarly, the CMAH gene of subject R carried six mutations with heterozygosity at c.142G>A, c.187A>G, c.268T>A, c.327A>C, c.773G>A and c.1603G>A, representing a new diplotype including a novel synonymous single nucleotide polymorphism (SNP) in exon 7 (c.773 G>A: Arg258Gln). The CMAH diplotype in subjects K and R was different from major diplotype in blood type B cats. This study is the first to report CMAH variants in cats with discordant blood types between CARD and TUBE methods. These results could assist in the classification of feline AB blood types for transfusion medicine to avoid blood incompatibilities.

Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS). Part 1: Definitions and clinical signs

OBJECTIVE

To use a systematic, evidence-based consensus process to develop definitions for transfusion reactions in dogs and cats.

DESIGN

Evidence evaluation of the literature was carried out for identified transfusion reaction types in dogs and cats. Reaction definitions were generated based on synthesis of human and veterinary literature. Consensus on the definitions was achieved through Delphi-style surveys. Draft recommendations were made available through industry specialty listservs and comments were incorporated.

RESULTS

Definitions with imputability criteria were developed for 14 types of transfusion reactions.

CONCLUSIONS

The evidence review and consensus process resulted in definitions that can be used to facilitate future veterinary transfusion reaction research.

Accuracy of a point-of-care major crossmatch test and risk factors for major crossmatch incompatibility in cats

Major crossmatch testing can help identify immunologic incompatibilities between blood donors and recipients; however, there are limited studies describing the accuracy of point-of-care crossmatch tests. The first aim of this study was to determine if a gel-based, point-of-care major crossmatch method (GEL-CM), without antiglobulin-enhancement, could accurately detect compatible and incompatible donor-recipient pairings, using an antiglobulin-enhanced laboratory-based major crossmatch method (LAB-CM) as the reference standard. The second aim was to describe the incidence of, and risk factors for, major crossmatch incompatibility in cats. Nineteen previously-transfused cats and 32 transfusion-naïve cats, representing 132 unique donor-recipient pairings, were included in this study. Both LAB-CM and GEL-CM tests were performed for most parings. There was poor agreement between the LAB-CM and GEL-CM results (kappa = 0.111; 95% confidence interval [CI], -0.093 to 0.314). Transfusion-naïve cats had incompatibility rates of 3% and 6% using LAB-CM and GEL-CM, respectively; previously-transfused cats had incompatibility rates of 32% and 26% using LAB-CM and GEL-CM, respectively. History of previous transfusion was the only identified cat risk factor for an incompatible LAB-CM (odds ratio [OR], 31.0; 95% CI, 3.77-254.98; P = 0.0019) and GEL-CM (OR, 5.7; 95% CI, 1.72-19.20; P = 0.0054). Further studies are needed to determine if GEL-CM can detect clinically-relevant immunologic incompatibilities that would result in transfusion reactions. Major crossmatch testing is of greater importance in cats that have previously received a transfusion.

Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS) Part 2: Prevention and monitoring

OBJECTIVE

To systematically review available evidence to develop guidelines for the prevention of transfusion reactions and monitoring of transfusion administration in dogs and cats.

DESIGN

Evidence evaluation of the literature (identified through Medline searches through Pubmed and Google Scholar searches) was carried out for identified transfusion reaction types in dogs and cats. Evidence was evaluated using PICO (Population, Intervention, Comparison, Outcome) questions generated for each reaction type. Evidence was categorized by level of evidence (LOE) and quality (Good, Fair, or Poor). Guidelines for prevention and monitoring were generated based on the synthesis of the evidence. Consensus on the final recommendations and a proposed transfusion administration monitoring form was achieved through Delphi-style surveys. Draft recommendations and the monitoring form were made available through veterinary specialty listservs and comments were incorporated.

RESULTS

Twenty-nine guidelines and a transfusion administration monitoring form were formulated from the evidence review with a high degree of consensus CONCLUSIONS: This systematic evidence evaluation process yielded recommended prevention and monitoring guidelines and a proposed transfusion administration form. However, significant knowledge gaps were identified, demonstrating the need for additional research in veterinary transfusion medicine.

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.

Prevalence of Blood Types and Alloantibodies of the AB Blood Group System in Non-Pedigree Cats from Northern (Lombardy) and Southern (Sicily) Italy

Simple Summary

The most important blood group system in cats is the AB, in which cats are classified as type-A, B or AB. Cats have antibodies against the blood type they do not possess, called alloantibodies. The aims of this study were to update blood type prevalence in cats from Northern Italy and study for the first time the blood type in cats from an insular region of Southern Italy, Sicily; to detect alloantibodies in these feline populations; to compare results with previous studies performed in Italy and between regions in Northern and Southern Italy. Cats from Southern Italy had the highest prevalence of type-B and type-AB, and the lowest prevalence of type-A blood in Italy. In particular, type-AB prevalence was higher than all previous reports in non-pedigree cats in Europe and the Italian prevalence of anti-type-B alloantibodies in type-A cats was the lowest reported worldwide. These results highlight the usefulness of regional studies to report different prevalences in feline blood types. Compatibility tests such as blood typing and cross matching must be considered fundamental in cats of any origin to ensure safe and efficient blood transfusion and to prevent neonatal isoerythrolysis.

Abstract

The aims of this study were to determine the prevalence of A, B and AB blood types and alloantibodies in non-pedigree cats from two regions, one in Northern and one in Southern Italy (Lombardy and Sicily, respectively). A total of 448 samples (52.0% from Northern and 48.0% from Southern Italy) were blood typed. The prevalence of A, B and AB blood types in northern and southern cats were 91.0%, 5.2%, 3.8%, and 77.2%, 12.1% and 10.7%, respectively. The prevalence of type-A blood in southern cats was significantly lower (p = 0.0001) than in northern cats, while type-B and AB blood were significantly higher (p = 0.0085 and p = 0.0051, respectively) in Southern compared to Northern Italian cats. Alloantibodies against type-A blood were found in 94.1% of type-B cats, 11.2% of type-A cats had alloantibodies against type-B blood, while no type-AB cats had alloantibodies with no significant difference between the two Italian populations. Type-AB prevalence in non-pedigree cats in Southern Italy was the highest reported in Europe. Italian type-A cats had the lowest worldwide prevalence of alloantibodies against type-B blood. These results highlight the usefulness of regional studies to report different prevalences in feline blood types and reinforce the importance of blood typing cats before transfusions and mating.

Comparison of Conventional Tube and Gel-Based Agglutination Tests for AB System Blood Typing in Cat

Gel technology is widely used for blood typing in human medicine. It has a number of advantages over routine tube testing, including standardization, stability, smaller sample volume, ease of performance and analysis, and speed. The aim of this study was to evaluate feline blood typing using the gel column technique. TUBE agglutination typing was performed in 143 feline blood samples from blood donors and recipients, healthy and sick patients, and whole-blood units anticoagulated with ethylenediamine tetraacetic acid or citrate phosphate dextrose adenine. Plasma from type B cats was used as anti-A reagent, Triticum vulgaris lectin as anti-B reagent, and the control was saline solution. Agglutination in backtyping of types B and AB samples with type A red blood cells (RBCs) was used to confirm whether the samples were type B (presence of alloantibodies) or type AB (absence of alloantibodies). Blood typing in a neutral gel column technique (GEL) using the same anti-A and anti-B reagents was performed on duplicate samples. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive predictive value, negative predictive value, overall accuracy, and Cohen κ coefficient (κ) for GEL were calculated, with TUBE considered the gold standard technique. Of 143 samples typed with TUBE, 98 (68.5%) were type A, 25 (17.5%,) type B, and 20 (14.0%) type AB. Backtyping confirmed the categorization of all types B and AB samples. Of these samples, gel testing produced 115 (80.4%) concordant results; a mixed-field agglutination pattern (layers of RBCs at both the top and at the bottom of the gel in either the A or B gel column) was seen in 27 samples, and one type B sample was misidentified as type AB. If the mixed-field pattern was interpreted as a negative result, 141/143 (98.6%) samples showed concordant results with an overall accuracy of the GEL of 100.0% for type A, 98.9% for type B, and 99.1% for type AB. Strength of agreement was very good (κ = 0.97). When the same anti-A and anti-B reagents are used, GEL is a sensitive and specific method for blood typing feline samples. Until additional studies have been performed, mixed-field patterns obtained in GEL testing should be classified as negative results.

The Prevalence of Blood Groups in Domestic Cats in the Saskatoon and Calgary Areas of Saskatchewan and Alberta, Canada

The purpose of this study was to evaluate blood types of domestic cats in two cities in Western Canada (Saskatoon, Saskatchewan and Calgary, Alberta), as well as to determine the risk of mismatched transfusion and neonatal isoerythrolysis. Several cat studies around the world have shown variability in the prevalence of blood types in domestic and pedigree cats. Canadian data based on feline blood types is based out of Montreal. In this study the cohort of cats revealed a higher than anticipated prevalence; of 5% type B and 0.6% AB blood types. In our study, blood typing was performed in 400 domestic cats; 200 in Saskatoon and 200 in Calgary. Blood typing was performed using the gel tube method and the risk of transfusion mismatch (MT) was estimated by adding the risk of a major transfusion reaction and the risk of a minor transfusion reaction. The risk of neonatal isoerythrolysis (NI) was estimated according to the equation (p²)(q²) + 2pq(q²), with q being the b allele frequency and p = 1 – q. There was an identical frequency for feline blood types in both Saskatoon and Calgary cats, with 96% type A, 4% type B, and 0% AB. Based on these percentages, the risks of MT and NI in domestic cats were 7.6 and 4 % respectively. The frequency of type B cats in the population was similar to that in the previous Canadian study. These results demonstrate regional differences in prevalence of type B blood in domestic shorthairs across the world and serve to reinforce recommendations to blood type prior to transfusion or mating.

Acute hemolytic reaction due to A-B mismatched transfusion in a cat with transient AB blood type

OBJECTIVE

To document a case of transient AB blood type indicated by immunochromatography in a type B cat following administration of an incompatible type A transfusion.

CASE SUMMARY

A 7-month-old neutered male domestic longhair cat was evaluted for anemia, pigmenturia, and intravascular hemolysis 1 day after receiving a feline whole blood transfusion. Neither blood donor nor patient had been blood-typed or crossmatched. The cat presented in shock with a severe non-regenerative anemia, hyperlactatemia, hyperbilirubinemia, hemoglobinemia, hemoglobinuria, and a positive saline slide agglutination test. Immunochromatographic blood typing tests initially indicated the cat had type AB blood, but crossmatch tests with blood from type A and type B donors suggested that the cat was type B. The cat was transfused with type B packed red blood cells without apparent complications and clinically improved. The cat's blood type reverted to type B once all the previously transfused type A cells were cleared from circulation. Furthermore, the original donor was subsequently identified as a Siamese cat and confirmed to have type A blood. While the cause of the original anemia remained unknown, the cat completely recovered and regained a normal hematocrit.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first documented report of transient AB blood type diagnosed using immunochromatography after a transfusion mismatch and shows the utility of crossmatching or back-typing to identify the cat's correct blood type during the hemolytic transfusion reaction.

Molecular characterization of cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) associated with the erythrocyte antigens in dogs

Background

N-glycolylneuraminic acid (Neu5Gc) is synthesized from its precursor N-acetylneuraminic acid (Neu5Ac) by cytidine-5′-monophospho-N acetylneuraminic acid hydroxylase (CMAH), which is encoded by the CMAH gene. Most mammals have both Neu5Gc and Neu5Ac, but humans and ferrets have only Neu5Ac because of loss-of-function mutations. Dogs and cats are polymorphic for Neu5Gc and Neu5Ac expression like cats, in which the CMAH gene is responsible for the AB Blood group system. Although the CMAH gene has been characterized in many species, not much is known about it in dogs. In this study, we cloned the dog CMAH cDNA, and performed mRNA expression analysis of this gene in several organs. We also identified single nucleotide polymorphisms (SNPs) in the CMAH gene.

Results

We cloned the 1737-bp open reading frame of the dog CMAH gene. This gene consists of at least 14 coding exons and codes for a polypeptide of 578 amino acids and is located on chromosome 35. The amino acid identities of dog CMAH with the corresponding sequences from cat, pig, chimpanzee, mouse, and rat were high (89 to 93%). RT-PCR analysis showed that the dog CMAH cDNA was expressed in various tissues. We identified four exonic SNPs (three synonymous and one non-synonymous), 11 intronic SNPs, and an indel in 11 dog breeds by analyzing the nucleotide sequences of the 14 exons, including the coding region of CMAH. In the genotype of the non-synonymous SNP, c.554 A > G (p.Lys185Arg), in a total of 285 dogs of seven different breeds, the allele G was widely distributed, and the allele A was the most frequent in the Shiba dogs. The dogs expressing Neu5Ac did not carry the loss-of-function deletion of CMAH found in humans and ferrets, and it remains unclear whether the point mutations influence the expression of Neu5Ac.

Conclusions

We characterized the canine CMAH gene at the molecular level for the first time. The results obtained in this study provide essential information that will help in understanding the molecular roles of the CMAH gene in canine erythrocyte antigens.

Prevalence of naturally occurring non-AB blood type incompatibilities in cats and influence of crossmatch on transfusion outcomes

BACKGROUND

Recognition of the feline red blood cell (RBC) antigen Mik and the presence of naturally occurring anti-Mik antibodies resulting in acute hemolytic transfusion reactions prompted the recommendation to perform a crossmatch before a cat's first RBC transfusion, but this guideline has not yet become a standard practice.

OBJECTIVE

To determine the prevalence of naturally occurring non-AB alloantibodies detectable by tube crossmatch, and to compare transfusion outcomes in cats with and without a crossmatch performed.

ANIMALS

Three hundred cats that received an RBC transfusion, with or without a major crossmatch performed.

METHODS

Retrospective study.

RESULTS

Major crossmatch incompatibilities were documented in 23 of 154 transfusion-naive cats (14.9%) and in 15 of 55 previously transfused cats (27%; P = 0.042). Type-specific packed RBCs (pRBCs) were administered to 167 and 82 cats with and without a crossmatch, respectively. Median volume of pRBCs administered during the first transfusion was 5.3 mL/kg (range, 2.4-18 mL/kg). Median change in PCV scaled to dose of pRBCs was +0.8%/mL/kg; administration of crossmatch-compatible pRBCs was not associated with a greater increase in PCV. Febrile transfusion reactions occurred more often in cats that received non-crossmatched (10.1%) compared to crossmatched (2.5%) pRBCs (P = 0.022). Seventy-six percent of cats that received pRBC transfusions survived to hospital discharge. A crossmatch was not associated with improved survival to discharge or at 30 or 60 days posttransfusion.

CONCLUSIONS AND CLINICAL IMPORTANCE

The prevalence of naturally occurring non-AB incompatibilities is sufficiently high to justify the recommendation to perform a crossmatch before all (including the first) RBC transfusions in cats.

Titres of alloantibodies against A and B blood types in non-pedigree domestic cats in Turkey: Assessing the transfusion reaction risk

The severity of a transfusion reaction depends on alloantibody titres within the recipients' blood. Determination of an agglutination titre of naturally occurring alloantibody may help to assess the risk of transfusion reactions following an unmatched transfusion in a cat population. In this group of 312 cats 227 had blood type A, 78 had blood type B, and seven had type AB blood. All type B cats tested showed gross evidence of agglutinating anti-A antibody with plasma titres ranging from 2 to 256. Among the 227 type A domestic cats tested for plasma anti-B alloantibody titres, 70% had gross agglutination with titres ranging from 2 to 16, while 17.6% had microscopic agglutination. The remaining 12.4% of the type A cats were negative for both gross and microscopic agglutination. Based on agglutinating titres, the relative risk of a transfusion reaction when type A or AB blood was given to a type B cat was 6.4% with acute severe reaction, acute mild reactions in 85.9% and premature red cell destruction in 7.7%. On the other hand, transfusion of type AB blood or type B blood to type A cats carries a potential risk of acute mild transfusion reaction in 4.4% and premature red cell destruction in 83.3%. Transfusion of type A or B blood to type AB cats results in no apparent clinical transfusion reactions.

Molecular Characterization of the Cytidine Monophosphate-N-Acetylneuraminic Acid Hydroxylase (CMAH) Gene Associated with the Feline AB Blood Group System

Cat’s AB blood group system (blood types A, B, and AB) is of major importance in feline transfusion medicine. Type A and type B antigens are Neu5Gc and Neu5Ac, respectively, and the enzyme CMAH participating in the synthesis of Neu5Gc from Neu5Ac is associated with this cat blood group system. Rare type AB erythrocytes express both Neu5Gc and Neu5Ac. Cat serum contains naturally occurring antibodies against antigens occurring in the other blood types. To understand the molecular genetic basis of this blood group system, we investigated the distribution of AB blood group antigens, CMAH gene structure, mutation, diplotypes, and haplotypes of the cat CMAH genes. Blood-typing revealed that 734 of the cats analyzed type A (95.1%), 38 cats were type B (4.9%), and none were type AB. A family of three Ragdoll cats including two type AB cats and one type A was also used in this study. CMAH sequence analyses showed that the CMAH protein was generated from two mRNA isoforms differing in exon 1. Analyses of the nucleotide sequences of the 16 exons including the coding region of CMAH examined in the 34 type B cats and in the family of type AB cats carried the CMAH variants, and revealed multiple novel diplotypes comprising several polymorphisms. Haplotype inference, which was focused on non-synonymous SNPs revealed that eight haplotypes carried one to four mutations in CMAH, and all cats with type B (n = 34) and AB (n = 2) blood carried two alleles derived from the mutated CMAH gene. These results suggested that double haploids selected from multiple recessive alleles in the cat CMAH loci were highly associated with the expression of the Neu5Ac on erythrocyte membrane in types B and AB of the feline AB blood group system.

Signalment and blood types in cats being evaluated as blood donors at two italian university blood banks

Data from potential feline blood donors presented at two university blood banks in Italy were recorded. Blood typing was performed using an immunochromatographic method. Over the three years of the study 357 cats representing 15 breeds, 45.3% female and 54.7% male, with a mean age of 3.8 years were evaluated. Of these 90.5% were blood type A, 5.6% type B, and 3.9% type AB. The majority of the cats (54.6%) were European DSH (92.3% were type A, 5.1% type B, and 2.6% type AB), and 21% were Maine Coon (MCO) cats (100% blood type A). The estimated frequencies of transfusion reactions following an unmatched transfusion between DSH (donors and recipients), MCO (donor and recipients), DSH donors and MCO recipients, and MCO donors and DSH recipients were 4.8%, 0%, 0%, and 5.1% for major reactions and 7.2%, 0%, 7.7%, and 0% for minor transfusions reactions, respectively. In a population of blood donors that includes DSH and MCO the risk of transfusion reaction is between 5% and 8% if typing is not performed on donor and recipient blood. Blood typing should therefore be performed before transfusion to remove the risk of transfusion reactions due to blood type incompatibilities.

Evaluation of a novel feline AB blood typing device

This prospective study evaluated a novel immunochromatographic (IC) blood typing test for the AB blood group system. Typing was conducted comparatively on ethylenediamine tetra-acetic acid-anticoagulated blood samples from 89 sick and 16 healthy cats with the IC test, as well as two tests as reference methods, a tube agglutination and a gel column test. The samples were between 0 and 10 days old (median 3 days) and were tested for haemolysis and agglutination; the packed cell volume ranged from 0.07 to 0.57 l/l (median 0.40 l/l). The reference methods agreed with each other in 100% of the test runs. Of the 85 samples tested as blood type A by the two reference methods, 80 were correctly identified by the IC test, four were misidentified as AB and one was rated inconclusive. All B samples were correctly typed. Two of the three AB samples were correctly identified by the IC test and one was rated inconclusive. The sample quality had no influence on test performance. Of 30 repeats, 28 were readable and showed agreement in 27 cases. The agreement of the IC test with the control methods was 96.1% for the 103 conclusive tests, and it showed high sensitivity and specificity for A and B antigen detection. It is suggested that AB results be reconfirmed with a laboratory method and that a ‘back-typing’ be performed with plasma from B samples to detect the presence of alloantibodies. Given its very good performance and ease of use, the IC test can be recommended for clinical settings.

Frequencies of blood types A, B, and AB in non-pedigree domestic cats in Beijing

BACKGROUND

Frequencies of blood types A, B, and AB in domestic cats vary geographically and among breeds and have not been reported in China.

OBJECTIVE

The purpose of this study was to survey the frequency of blood types in domestic cats in the Beijing area.

METHODS

A total of 262 cats from the city of Beijing were blood-typed using a standard tube agglutination assay. All cats were nonpedigree domestic shorthaired and longhaired cats; purebred cats were excluded. Serum obtained from type-B cats and a lectin (Triticum vulgaris) solution served as anti-A and anti-B reagents, respectively. The presence of alloantibodies was also determined in some cats.

RESULTS

The frequency of blood types was 88.2% type A, 11.4% type B, and 0.4% type AB. The tube assay resulted in 3+ to 4+ agglutination reactions with either the anti-A or anti-B reagents. The 1 type AB sample showed 3+ agglutination with both anti-A and anti-B reagents; the plasma of that sample did not react with either type-A or type-B RBCs. Tested type-B cats had strong anti-A antibodies.

CONCLUSIONS

The frequency of blood type B in the Beijing area was relatively high and similar to that reported for other Asian countries and Australia. Blood-typing is recommended to match donors and recipients before transfusion therapy and planned matings to avoid hemolytic transfusion and neonatal isoerythrolysis reactions, respectively, due to blood-type incompatibility.

Comparison of five blood-typing methods for the feline AB blood group system

Objective-To compare the ease of use and accuracy of 5 feline AB blood-typing methods: card agglutination (CARD), immunochromatographic cartridge (CHROM), gel-based (GEL), and conventional slide (SLIDE) and tube (TUBE) agglutination assays. Sample Population-490 anticoagulated blood samples from sick and healthy cats submitted to the Transfusion or Clinical Laboratory at the Veterinary Hospital of the University of Pennsylvania. Procedures-Sample selection was purposely biased toward those from anemic, type B, or type AB cats or those with autoagglutination. All blood samples were tested by use of GEL, SLIDE, and TUBE methods. Fifty-eight samples were also tested by use of CARD and CHROM methods. The presence of alloantibodies in all cats expressing the B antigen as detected by use of any method was also assessed. Results-Compared with the historical gold-standard TUBE method, good to excellent agreement was achieved with the other typing tests: CARD, 53 of 58 (91% agreement); CHROM, 55 of 58 (95%); GEL, 487 of 490 (99%); and SLIDE, 482 of 487 (99%; 3 samples were excluded because of autoagglutination). Four of the samples with discordant test results originated from cats with FeLV-related anemia. Conclusions and Clinical Relevance-Current laboratory and in-clinic methods provide simple and accurate typing for the feline AB blood group system with few discrepancies. Retyping after in-clinic typing with the GEL or TUBE laboratory methods is recommended to confirm any type B or AB cats.

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.

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.

Cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) mutations associated with the domestic cat AB blood group

Background

The cat has one common blood group with two major serotypes, blood type A that is dominant to type B. A rare type AB may also be allelic and is suspected to be recessive to A and dominant to B. Cat blood type antigens are defined, N-glycolylneuraminic acid (NeuGc) is associated with type A and N-acetylneuraminic acid (NeuAc) with type B. The enzyme cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) determines the sugar bound to the red cell by converting NeuAc to NeuGc. Thus, mutations in CMAH may cause the A and B blood types.

Results

Genomic sequence of CMAH from eight cats and the cDNA of four cats representing all blood types were analyzed to identify causative mutations. DNA variants consistent with the blood types were genotyped in over 200 cats. Five SNPs and an indel formed haplotypes that were consistent with each blood type.

Conclusion

Mutations in type B cats likely disrupt the gene function of CMAH, leading to a predominance of NeuAc. Type AB concordant variants were not identified, however, cDNA species suggest an alternative allele that activates a downstream start site, leading to a CMAH protein that would be altered at the 5' region. The cat AB blood group system is proposed to be designated by three alleles, A > a^ab > b. The A and b CMAH alleles described herein can distinguish type A and type B cats without blood sample collections. CMAH represents the first blood group gene identified outside of non-human primates and humans.

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.

Comparison of various blood-typing methods for the feline AB blood group system

OBJECTIVE

To compare feline blood-typing results determined by use of the card (CARD), gel (GEL), tube (TUBE), University of Pennsylvania (Penn) tube, and Penn slide tests.

SAMPLE POPULATION

Blood samples from 38 healthy cats.

PROCEDURES

Blood samples, anticoagulated with EDTA, were screened by use of each blood-typing method according to manufacturers' protocols.

RESULTS

On the basis of the standard Penn tube and slide test results, 20, 11, and 7 cats were classified as type A positive, type B positive, and type AB positive, respectively. The same results were obtained with the anti-B and anti-B reagents of the TUBE test. Use of anti-A antibodies of original polyclonal and current monoclonal CARD tests resulted in mostly 2+ to 3+ (scale, 0 to 4+) agglutination reactions with blood samples from type A-positive cats; agglutination reactions with blood samples from type AB-positive cats were weak (1+). The anti-B lectin of the CARD test induced a 2+ to 4+ reaction with blood from all type B- and type AB-positive cats. Use of the GEL test allowed recognition of type A and type B blood samples; following addition of anti-A serum to control columns, type B blood was differentiated from type AB blood.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of the in-practice CARD test allows identification of type A- and type B-positive cats, but weak reactions of type AB blood with the anti-A monoclonal antibody raise concerns. The modified GEL and TUBE tests appear to be reliable clinical laboratory methods for feline blood typing.

The prevalence of feline A/B blood types in the Sydney region

OBJECTIVE

To determine the distribution of A/B blood types in pedigree and crossbred cats in the Sydney region, and to estimate the associated risk of administering incompatible blood in an unmatched random transfusion.

DESIGN

A prospective/retrospective study of blood specimens collected from both sick and healthy cats.

MATERIALS AND METHODS

Blood was collected from 355 cats from the Sydney region over a 12-year period from 1992 to 2003. Specimens were obtained from 187 domestic crossbred cats (short and long-haired) and 168 pedigree cats. The blood type of each cat was determined by one of three different laboratories using standard methods that varied over the duration of the survey.

RESULTS

The distributions of blood types obtained by the three laboratories were not significantly different. The prevalence of type-A, type-B and type-AB blood types in crossbred cats was 62%, 36% and 1.6%, respectively. This is the highest percentage of type-B cats so far reported for an outbred population of domestic cats, and is significantly higher than the 26% reported previously for cats in the Brisbane region. The calculated frequency for the type-B allele assuming Hardy-Weinberg equilibrium for this feline population is 0.60; the corresponding frequency of the type-A allele is thus approximately 0.40. The calculated proportion of random transfusions from this population giving rise to an incompatible blood transfusion is 46%, with half of these being life-threatening events. The calculated proportion of random matings from this population at risk for developing neonatal isoerythrolysis is 23%. The distribution of A and B blood types for pedigree cats was in general agreement with data reported previously for cats in North America and Europe, suggesting that the distribution of blood types in these purebred populations is relatively consistent throughout the world.

CONCLUSIONS

The prevalence of type B cats in the owned domestic and pedigree cat population is so high that blood typing or cross matching prior to transfusion should be mandatory, except in Siamese/Oriental cats.

Frequencies of feline blood types in northern Portugal

The frequencies of feline blood types in northern Portugal were studied by surveying 185 pedigreed and nonpedigreed cats. Blood typing was performed by the traditional tube method. As a single group, the majority of cats were type A (90.3%), 3.8% were type B, and 5.9% were type AB. Among pedigreed cats, 19 were Siamese and 7 were Persian; all but 1 were type A. Among nonpedigreed cats, 89.3% were type A, 4.4% were type B, and 6.3% were type AB.

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).

Blood type A and B frequencies in Turkish Van and Angora cats in Turkey

Blood typing of domestic cats has been performed in domestic and purebred cats in various parts of the world and is important in clinical practice in order to prevent neonatal isoerythrolysis (NI) and acute haemolytic transfusion reactions. Prevalence of blood types vary greatly between breeds of cats. Turkish Van and Angora cats are different breeds that originated in geographically distinct regions of Turkey. The present survey determined the frequency of blood types in these Turkish pedigreed cats in Turkey. Ethylenediaminetetraacetic-acid anti-coagulated blood of a total of 113 Turkish Van and Angora cats were examined for blood typing using a slide and tube agglutination assay. Of the 85 Van cats surveyed, 40% had type A, and 60% had type B blood. Of the 28 Turkish Angora cats, 53.6% had type A, and 46.4% had type B blood. No type AB cats were found between both breeds. There was no significant association between blood types and gender of both Angora and Van cats or eye colours of Van cats (P > 0.05). Although these are limited surveys, the overall prevalence of type B cats in these two breeds was very high compared with the results of previous studies worldwide. It appears likely that blood type incompatibilities responsible for feline NI and transfusion reactions are occurring in these breeds. The risk of transfusion incompatibility in Turkish Angora and Van cats was 46.4 and 60%, respectively. It is therefore strongly recommended to breeders and clinicians that blood typing be performed prior to breeding and transfusing cats.

Anemia, splenomegaly, and increased osmotic fragility of erythrocytes in Abyssinian and Somali cats

OBJECTIVE

To determine clinical and clinicopathologic features of a chronic intermittent severe hemolytic anemia characterized by erythrocyte osmotic fragility in Abyssinian and Somali cats.

DESIGN

Case series.

ANIMALS

13 Abyssinian and 5 Somali cats.

PROCEDURES

History, pedigree information, and results of routine laboratory tests, special erythrocyte studies, and histologic evaluation of splenic and hepatic specimens were analyzed.

RESULTS

Age at which clinical signs of anemia were first apparent ranged from 6 months to 5 years. Ten cats had splenomegaly. Most often, the PCV was between 15 and 25%, but it was as low as 5% at some times. The anemia was characterized by macrocytosis and mild to moderate reticulocytosis, but no poikilocytosis. Hyperglobulinemia, lymphocytosis, mild hyperbilirubinemia, and high hepatic enzyme activities were common findings. Results of Coombs tests and tests for infectious diseases were negative. The erythrocytic osmotic fragility was high in affected cats (mean osmotic fragility, 0.66 to 0.78%), compared with healthy cats (0.48 to 0.58). No specific membrane protein abnormality, erythrocyte enzyme deficiency, or hemoglobinopathy was identified. Histologic evaluation of splenic and hepatic specimens revealed extramedullary hematopoiesis and hemosiderosis. Four of the 5 Somali cats were closely related.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of results of pedigree analyses, the apparent breed predilection, and the exclusion of other known causes of anemia in cats, we believe that the hemolytic anemia in these cats was likely a result of a novel hereditary erythrocyte defect. A genetic predisposition to immune-mediated destruction of erythrocytes could not be ruled out.

Measurement of titres of naturally occurring alloantibodies against feline blood group antigens in the UK

Measurement of anti-A and anti-B haemagglutinating alloantibody titres was performed on serum samples from both pedigree (n = 61) and non-pedigree (n = 43) cats previously typed using a commercial blood typing kit. All 40 type B cats had anti-A antibody with titres ranging from 4 to 1600. Among the 61 type A sera tested, an anti-B agglutination titre of greater than 2 was recorded in 16.4 per cent. There was no significant association between serum alloantibody titre and cat breed or gender (P > 0.05).

The AB blood group system in wild felids

The blood type of 131 non-domesticated felids belonging to 26 felid species was surveyed in this study. Based upon a tube hemagglutination assay established for domestic cats, 80% of felids had type-A, 18% type-B, and 2% type-AB blood. Felids in the Puma group and African and Asian golden cats had blood type B, whereas all other species were found to have blood type A. Two cheetahs and one bobcat had type-AB blood. Red cell glycolipids analysed by high performance thin layer chromatography revealed a similar ganglioside pattern in wild cats as reported in domestic cats. Independent of the AB blood group system, incompatible blood crossmatch reactions were detected between different felid groups. In conclusion, wild felids display the same AB-erythrocyte antigens as domestic cats, and the same blood typing procedures can be applied for wild and domestic felids.

Determination of the prevalence of feline blood types in the UK

The efficacy and diagnostic accuracy of a new desk-top feline blood typing kit was evaluated by comparing the results of the kit with traditional blood typing methods on 35 feline blood samples. The kit was then used to blood type 139 non-pedigree cats from Scotland and the north of England and 207 pedigree cats from throughout the UK. Of the non-pedigree cats, 87.1 per cent were type A, 7.9 per cent were type B and 5.0 per cent were type AB, while of the pedigree cats, 54.6 per cent were type A, 40.1 per cent were type B and 5.3 per cent were type AB. The majority (121 out of 207) of these pedigree cats were British shorthaired, of which 39.7 per cent were type A, 58.7 per cent were type B and 1.6 per cent were type AB. No cats were identified that failed to express the type A and/or type B antigens. The prevalence of type AB cats appears to be higher in this study than previously reported. The prevalence of blood types within specific pedigree breeds in the UK appears to vary from that reported elsewhere.

Feline transfusion medicine. Blood types and their clinical importance

Anemia is the most common indications for a blood transfusion in cats and fresh whole blood is typically administered. Recent experimental studies and clinical reports have elucidated the importance of feline blood types in transfusion medicine. The AB blood group system, the only recognized feline blood group system, consists of three blood types: type A is most common, type B is frequently found in certain breeds, and type AB occurs rarely. The blood type frequently varies geographically among domestic shorthair cats and between breeds. Because of the presence of naturally occurring alloantibodies, only AB-matched transfusions are effective and safe. Blood typing is now readily available and incompatibilities are easily recognized with blood crossmatching tests. Owing to the general presence of strong anti-A alloantibodies in type B cats, type A blood given to a type B cat results in life-threatening acute hemolytic transfusion reactions. Immediate withdrawal of a transfusion and supportive care may save a patient. Other transfusion reactions, unrelated to AB mismatch, cause only mild and transient signs. Peculiarities of feline blood banking also are reviewed.

Distribution of feline blood types detected in the Copenhagen area of Denmark

The purpose of the present study was to make the first survey of the distribution of feline AB blood types in the Copenhagen area of Denmark. A total of 244 cats (139 purebred cats and 105 Domestic Shorthair cats) were tested. 93% of all tested cats had blood type A. Neither an AB nor an O type cat was detected and thus, the frequency of blood type B among all tested cats was 7%. Most type B cats were purebred cats (Birman, British Shorthair and Persian cats). No association between sex and blood type could be demonstrated among British Shorthair and Persian cats. Thus, the present study indicates that cats in Denmark predominantly have blood type A, and that blood type B cats are rare, except for certain breeds such as Birman and British Shorthair cats.

Alloantibodies against A and B blood types in cats

This study characterizes the naturally occurring feline alloantibodies against A and B blood type. All examined type-A and type-B cats had naturally occurring antibodies against erythrocytes of the opposite blood type. In order to determine the class of immunoglobulins, sera from cats were analyzed using incubation with 2-mercaptoethanol (2-ME), immunoprecipitation, and gel filtration. Type-A cats had weak agglutinins of the IgM class and weak hemolysins which consisted of approximately equal parts of IgG and IgM class. Type-B cats had strong hemagglutinins and hemolysins mostly of the IgM class. Colostral antibodies were detectable in newborns as early as 4 h after birth and their own alloantibody production started at 6-8 weeks of age. The presence of naturally occurring alloantibodies, in particular the anti-A alloantibodies, renders cats susceptible to clinical incompatibility reactions.

Acute hemolytic transfusion reaction in an Abyssinian cat with blood type B

After receiving a transfusion with unmatched blood, an anemic Abyssinian cat developed an acute hemolytic transfusion reaction. Similar to many other purebred cats, the recipient had type B blood with strong serum anti-A alloantibodies, whereas the donor had blood type A. Subsequent transfusions with type B blood proved effective and without adverse reactions. This case of a clinical A-B incompatibility reaction emphasizes the need for blood typing and/or crossmatching prior to transfusing cats.

Drugs used for disorders of coagulation

Bleeding and thrombosis are altered states of hemostasis. Inhibition of normal hemostatic mechanisms results in spontaneous hemorrhage, whereas excessive hemostasis results in thrombus formation. The drugs used to prevent and treat thrombosis and those used to arrest bleeding are the subjects of this article.