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

ACVIM consensus statement on the treatment of immune thrombocytopenia in dogs and cats

Management of immune thrombocytopenia (ITP) in dogs and cats is evolving, but there are no evidence-based guidelines to assist clinicians with treatment decisions. Likewise, the overall goals for treatment of ITP have not been established. Immunosuppressive doses of glucocorticoids are the first line treatment, but optimal treatment regimens beyond glucocorticoids remain uncertain. Additional options include secondary immunosuppressive drugs such as azathioprine, modified cyclosporine, and mycophenolate mofetil, usually selected based on clinician preference. Vincristine, human IV immunoglobulin (hIVIg), and transfusion of platelet or red blood cell-containing products are often used in more severe cases. Splenectomy and thrombopoietin receptor agonists are usually reserved for refractory cases, but when and in which patient these modalities should be employed is under debate. To develop evidence-based guidelines for individualized treatment of ITP patients, we asked 20 Population Intervention Comparison Outcome (PICO) format questions. These were addressed by 17 evidence evaluators using a literature pool of 288 articles identified by a structured search strategy. Evidence evaluators, using panel-designed templates and data extraction tools, summarized evidence and created guideline recommendations. These were integrated by treatment domain chairs and then refined by iterative Delphi survey review to reach consensus on the final guidelines. In addition, 19 non-PICO questions covering scenarios in which evidence was lacking or of low quality were answered by expert opinion using iterative Delphi surveys with panelist integration and refinement. Commentary was solicited from multiple relevant professional organizations before finalizing the consensus. The rigorous consensus process identified few comparative treatment studies, highlighting many areas of ITP treatment requiring additional studies. This statement is a companion manuscript to the ACVIM Consensus Statement on the Diagnosis of Immune Thrombocytopenia in Dogs and Cats.

Impact of a cell salvage device on blood transfusions to dogs undergoing surgery at a referral veterinary hospital

OBJECTIVE

To determine the number of homologous blood transfusions received by canine surgical patients after introducing a cell salvage device (CSD), trends in surgeries requiring blood transfusion, and the incidence of transfusion reactions.

STUDY DESIGN

Retrospective study.

SETTING

Single referral hospital.

ANIMALS

All dogs having surgery at a single center (November 2015 to February 2021).

INTERVENTIONS

Medical records of dogs having surgical treatment, including those that received either an autologous or homologous blood transfusion, were reviewed. The surgical patients were the baseline population, and the 2 transfusion groups were compared within this population to analyze the trends.

MAIN RESULTS

A total of 37 and 86 dogs received autologous and homologous blood transfusions, respectively. There was an upward trend in the number of total monthly blood transfusions. No significant increase in the monthly number of homologous transfusions was observed before or after acquisition of the CSD. There was also an upward trend in total monthly surgeries, including those with higher risks of hemorrhage. Dogs receiving homologous blood transfusions had a higher incidence of clinical signs consistent with transfusion reactions (6.98%).

CONCLUSIONS

An upward trend in autologous blood transfusions was seen with the introduction of a CSD. Hospitals with large surgical caseloads at high risk of hemorrhage may see a decreased need for outsourced blood products with the use of the CSD. The device can lead to a more responsible use of an increasingly scarce resource and decrease the risk of a blood transfusion reaction in dogs.

Evaluation of post-transfusion RBC alloimmunization in dogs using a gel-column crossmatch with and without anti-canine globulin enhancement

A blood crossmatch is essential to ensure RBC compatibility for previously transfused dogs. There is no gold standard crossmatch method for dogs, although the standards used most commonly by academic institutions and reference laboratories are the tube and gel-column crossmatches. Addition of anti-canine globulin (ACG) has been suggested to increase detection of RBC incompatibilities. Our objective was to determine if there is a correlation between results of a standard and an ACG-enhanced gel-column crossmatch in detecting post-transfusion RBC alloimmunization. Pre- and post-transfusion serum or plasma samples were obtained from 33 dogs for major crossmatches to 1-6 (median: 3) blood donors. Crossmatches were performed with (n = 202) and without (n = 202) ACG, with results scored by 4 observers, 3 of whom were anonymized. Ten of 33 (30%) dogs had major crossmatch incompatibilities post-transfusion. RBC incompatibilities (2-4+ agglutination) were detected only with ACG in 4 dogs, only without ACG in 3 dogs, and with both methods in 3 dogs. There was fair correlation between crossmatch methods for determination of compatibility (ρ = 0.34; p < 0.001) and incompatibility (ρ = 0.35; p < 0.001) scores. Among 4 observers, there was near-perfect agreement in determining compatibility (κ = 0.97; p < 0.001) and substantial agreement in overall scoring of incompatibility (κ = 0.77; p < 0.001). Our results suggest that detection of RBC incompatibilities in dogs can be maximized by performing a gel-column crossmatch both with and without ACG enhancement.

Major crossmatch compatibility of rabbit blood with rabbit, canine, and feline blood

OBJECTIVE

To evaluate the major crossmatch compatibility between rabbit recipients, rabbit donors, and the major canine and feline blood types.

DESIGN

Prospective in vitro study in December 2021.

SETTING

Academic veterinary teaching hospital.

ANIMALS

Whole blood samples were collected from 11 healthy New Zealand White rabbits (Oryctolagus cuniculus) with no previous transfusion history. Three pigtail segments were acquired from dog erythrocyte antigen (DEA)-1-positive, DEA-1-negative, and feline type A blood units. Whole blood was collected from a healthy type B blood donor cat.

INTERVENTIONS

Blood from each rabbit recipient underwent a major crossmatch using standard tube crossmatch methodology with itself and the following donor blood types: rabbit, DEA-1-positive, DEA-1-negative, feline type A, and feline type B.

MEASUREMENTS AND MAIN RESULTS

Self-crossmatches and crossmatches between rabbit recipients and conspecific donors were negative for hemolysis and agglutination. Crossmatches between rabbit recipients and canine and feline donors yielded no hemolysis but produced varying degrees of macroscopic and microscopic agglutination. Rabbit recipients had 1.4 (95% confidence interval: 1.1-1.8) times the risk of macroscopic agglutination when major crossmatched with canine blood compared to feline blood. No significant difference in agglutination was found between DEA-1-positive and DEA-1-negative or feline type A and type B donors.

CONCLUSIONS

These findings support allogeneic blood transfusions between rabbits being highly compatible and suggest rabbits have naturally occurring alloantibodies against both canine and feline red blood cells. However, feline red blood cells had a lower rate of in vitro incompatibility on major crossmatch, suggesting potentially higher in vivo compatibility if an emergency xenotransfusion is needed. Further prospective research is needed to determine if xenotransfusion is associated with a higher incidence of acute and delayed transfusion reactions in rabbits than allogeneic transfusions.

Retrospective evaluation of indications, transfusion protocols, and acute transfusion reactions associated with the administration of lyophilized canine albumin: 53 cases (2009-2020)

OBJECTIVES

To describe the administration of lyophilized canine albumin (LCA) and determine the increase in serum albumin concentrations post-LCA transfusion. To describe the incidence and types of acute transfusion reactions (TRs) and associated outcome in dogs presenting to a veterinary teaching hospital.

DESIGN

Retrospective and descriptive study from 2009 to 2020.

SETTING

University teaching hospital.

ANIMALS

Fifty-three client-owned dogs included in the study if they received an LCA transfusion and had vital sign monitoring recorded for at least for 4 hours after starting the LCA transfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The 53 dogs available for study inclusion received 64 LCA transfusions. Signalment; underlying disease; indications for LCA transfusion; pre- and posttransfusion serum albumin concentration; volume, concentration, and dose of LCA; duration of transfusion; administration of other blood products or synthetic colloids; occurrence, timing, and type of TR; length of hospitalization; and outcome were recorded. Serum albumin concentrations increased post-LCA transfusion, with a median dose of 0.56 g/kg and a median posttransfusion serum albumin increase of 3 g/L (0.3 g/dL) (P = 0.008). TRs occurred in 13 of 64 (20.3%) transfusion events. Volume per kilogram, dose (g/kg), concentration, duration of transfusion, and additional administration of synthetic colloids were not associated with TRs. Three (23%) TRs were classified as febrile nonhemolytic transfusion reaction, 5 (38.5%) as transfusion-associated dyspnea (development of respiratory distress and limited diagnostics), and 5 (38.5%) had clinical signs that could not be defined by any 1 TR category. Six (46.1%) of 13 events were nonsevere, 5 (38.5%) were severe, and 2 (15.4%) were life-threatening.

CONCLUSIONS

Administration of LCA can be used to increase serum albumin concentrations, although the clinical implications of this increase are unknown. Acute TRs associated with LCA are relatively frequent and can be life-threatening. Careful monitoring is vital.

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.

Clinical Use of Canine Thawed Refrigerated Plasma: A Historical Case Series

Thawed plasma (TP) refers to defrosted fresh frozen plasma stored refrigerated. TP is used in human medicine for the rapid provision of coagulation factors and resuscitation of haemorrhagic shock, but its use in dogs is poorly described. The objectives of this historical case series were to describe the reasons for TP transfusion, treatment outcomes, and adverse events associated with canine TP transfusions in a veterinary teaching hospital. We hypothesised that TP would be used most commonly for the treatment of haemorrhage secondary to anticoagulant rodenticide intoxication and trauma. Blood bank plasma transfusion logs were searched to identify dogs that received at least one unit of TP between December 2015 and June 2021. Briefly, 166 dogs received a total of 262 units of TP. Anticoagulant rodenticide intoxication (37/166, 22.3%) was the most common reason for transfusion, followed by traumatic haemorrhage (23, 13.9%) and spontaneous haemoperitoneum (22, 13.2%). The majority of dogs received one unit of TP (111/166, 67.1%) and pRBCs were commonly simultaneously transfused with TP (65, 39.2%). Severe prolongations of prothrombin time and activated partial thromboplastin time were reduced following TP transfusions. Allergic reactions were the most common transfusion reaction (19/166, 11.4%). Most dogs survived to discharge (101/166, 60.8%).

Surgical interventions and outcome in a population of feline trauma patients

OBJECTIVE

To determine signalment, injury type, trauma severity score, and outcome of feline trauma patients undergoing surgical (emergency room [ER] and operating room [OR]) and nonsurgical treatments in addition to time to surgery, specialty services involved, and cost in the OR surgery population.

DESIGN

Retrospective evaluation of medical record and hospital trauma registry data on feline trauma cases.

SETTING

University teaching hospital.

ANIMALS

Two hundred and fifty-one cats presenting for traumatic injury between May 2017 and July 2020.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographics and outcomes were compared for cats undergoing surgical intervention in an OR (12%, 31/251) or an ER (23%, 58/251) setting and feline trauma patients without surgical intervention (65%, 162/251). Between the 2 surgical groups, 99% survived to discharge compared to 73.5% of the nonsurgical group (P < 0.0001). For the OR surgical cohort, electronic medical records were reviewed to determine the specialty surgery service involved, time to and duration of anesthesia and surgery, and visit cost. The most common surgery services involved were orthopedics (41%, 12/29) and dentistry (38%, 11/29), and the most common surgeries performed were mandibular fracture stabilization (8/29) and internal fixation for long bone fractures (8/29). The ER surgical group had a significantly lower Animal Trauma Triage score than the OR group (P < 0.0001), but a significant difference was not found between OR surgical and nonsurgical groups (P = 0.0553). No difference in modified Glasgow Coma Scale score was found between any groups.

CONCLUSIONS

Surgical intervention in feline trauma patients appears to be associated with higher survival rates, but no difference in mortality was found across surgery services. OR surgical intervention, in particular, orthopedic surgery, was associated with increased length of hospitalization, increased cost, and increased use of blood products.

Effect of donor blood storage on gel column crossmatch in dogs

BACKGROUND

Compared with fresh blood, stored equine donor blood results in spurious tube crossmatch incompatibilities. Interpretation of blood crossmatch results is considered subjective.

OBJECTIVES

We aimed to determine if the duration of canine donor blood storage impacts compatibility testing using a standard gel column crossmatch and evaluate interobserver variation in the interpretation of crossmatch results.

METHODS

Observational study. Whole blood segments were obtained from 23 canine packed red blood cell (RBC) units for use in crossmatches after storage for 0, 7, 14, 21, 28, and 35 days. Major and minor crossmatches were performed using serum and RBCs, respectively, from two to three healthy "recipient" dogs per unit. All crossmatch results were interpreted by four observers, of whom three were blinded.

RESULTS

All major crossmatches (n = 61) were compatible on day 0 and remained compatible through day 35 of storage. All minor crossmatches (n = 69) were compatible at all time points, except for five donor pairs with 1 to 3+ agglutination. Repeat testing of these five donor pairs confirmed crossmatch incompatibilities on days 0 through 35, with no change in the degree of incompatibility over time. There was substantial agreement among four observers in determining compatibility (κ = 0.94) and scoring incompatibility (κ = 0.76).

CONCLUSIONS

The current practice of performing canine crossmatches with whole blood segments stored for up to 35 days is acceptable, with no spurious changes in compatibility expected over time. The substantial interobserver agreement suggests that the gel column is suitable for performing canine crossmatches in a laboratory setting with multiple personnel.

Case report: Xenotransfusion of canine lyophilized platelets for hemostasis in a feline patient with post-operative abdominal hemorrhage

Objective

To describe the management of post-operative abdominal hemorrhage with a xenotransfusion of canine lyophilized platelets in a feline patient.

Case summary

A 9-year-old male castrated domestic shorthair presented for a spontaneous hemoabdomen secondary to hepatic amyloidosis. Clinically significant hemorrhage occurred in the perioperative and post-operative period and the patient received a massive transfusion and anti-fibrinolytic therapy in combination with a xenotransfusion of canine lyophilized platelets at 0.9 × 10⁹ particles/kg and recombinant human factor VIIa (rhFVIIa). The combination of these interventions decreased transfusion requirements in this patient and the xenotransfusion was well tolerated with no acute or immediate transfusion reactions noted.

New or unique information provided

This case report describes the xenotransfusion of canine lyophilized platelets in a feline patient with severe, non-compressible abdominal hemorrhage.

Evaluation of the utility and accuracy of body fluids containing red blood cells to determine canine and feline blood types

OBJECTIVE

To examine the accuracy of using body fluids macroscopically suspected to contain erythrocytes to determine the blood type in dogs and cats by use of an immunochromatographic cartridge (ICC), compared to systemic blood as the reference standard.

DESIGN

Prospective study.

SETTING

University teaching hospital.

ANIMALS

Thirty client-owned dogs and 8 cats.

INTERVENTIONS

Dogs and cats with a sanguineous or serosanguineous body fluid (SBF) that also required a blood sample were eligible for inclusion. PCV and blood type were determined in all blood and fluid samples. For body fluids with a low PCV and discordant blood type results compared to systemic blood, sample concentration and repeat blood typing from the fluid was performed when enough sample was available.

MEASUREMENT AND MAIN RESULTS

Body fluid samples consisted of 16 pleural (11 dogs; 5 cats), 12 peritoneal (10 dogs; 2 cats), and 4 canine pericardial effusions, 3 urine samples, and 1 each of feces and epistaxis from dogs and a seroma sample from a cat. Median (range) manual PCV of blood and fluid samples was 34% (14%-66%) and 6% (0.5%-70%) for dogs and 28% (14%-48%) and 14% (0.5%-19%) for cats, respectively. Dogs were correctly classified as being DEA 1 negative, DEA 1 positive, and DEA 1 weak positive when using body fluid for blood typing 13 of 14, 4 of 9, and 5 of 7, respectively. All reference blood type to fluid blood type (FBT) discordant results had a body fluid PCV equal to or below 2%. Subsequently concentrated body fluid samples had a PCV above 8% and repeat FBT matched reference blood type (RBT). All cats were classified as type A by all RBTs and FBTs.

CONCLUSIONS

Body fluids containing erythrocytes may be utilized to blood type dogs if sufficiently concentrated and type A cats.

The hemostatic profile of cold-stored whole blood from non-greyhound and greyhound dogs over 42 days

Objectives

To compare the hemostatic characteristics of cold-stored whole blood (CSWB) from non-greyhound dogs (NGD) and greyhound dogs (GD) over 42 days of storage, notably, platelet closure time (PCT) (NGD only), manual platelet count (PLT) (GD only), ellagic acid (INTEM) and tissue factor activated (EXTEM) rotational thromboelastometry, prothrombin (PT) and activated partial thromboplastin time (aPTT), fibrinogen concentration (FIB), and the activities of factors (F) FII, FV, FVII, FVIII, FIX, FX, FXIII antigen (FXIII:Ag), and von Willebrand factor antigen (vWF:Ag).

Design

Whole blood from 10 NGD and 10 GD, was refrigerated in CPD blood bags at 4°C for 42 days. Blood was analyzed before refrigeration (day 0) and at day 1 (d1), 3, 5, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, and 42. Multivariate linear mixed effects models were created to evaluate coagulation parameters over time and compare NGD and GD. Data are summarized as estimated marginal means with 95% confidence intervals. Significance was set at P < 0.05.

Results

The PCT for all NGD CSWB was above the device limit by d7. The PLT for GD CSWB did not change during storage. The mean alpha-angle for INTEM and EXTEM decreased to <50% of baseline at d38 and d31 for NGD, and d31 and d17 for GD CSWB. The mean maximum clot firmness (MCF) for INTEM and EXTEM reduced to <50% of baseline at d42 and d28 for both GD and NGD. PT and aPTT for NGD and GD increased over time. For NGD CSWB, the mean FVIII and vWF:Ag activities decreased to <50% of baseline at d7 and d28, respectively, and FIB reached 0.982 g/dL by d24. For GD CSWB, FVIII, FXIII:Ag and FV activities decreased to <50% of baseline by d3, d38, and d38, respectively, and FIB was 0.982 g/dL at baseline. Alpha-angle and MCF for both INTEM and EXTEM, and activities for FII, FV, FIX, FXIII:Ag were significantly lower, and vWF:Ag was significantly higher overall in GD CSWB compared with NGD. A significant difference in the pattern of change over time was detected between NGD and GD in EXTEM alpha-angle, INTEM and EXTEM MCF, FII, and FVIII activities.

Conclusions

The in vitro viscoelastic parameters of GD and NGD CSWB declines over 42 days, but numerous hemostatic parameters (INTEM and EXTEM alpha-angle and MCF, activity of FII, FV, FV, FVII, FIX, FX, FXIII:Ag, vWF:Ag, and FIB) remain within 50% of baseline for more than 14 days. CSWB from GD compared to NGD has reduced hemostatic activity overall, but a similar pattern of decline for most parameters over time.

Incidence of acute haemolysis in cats receiving canine packed red blood cells (xenotransfusions)

OBJECTIVES

The aim of this study was to report the incidence of transfusion reactions in cats, including acute haemolysis (AH), occurring within 24 h of receiving a xenotransfusion. An additional aim was to determine whether cases with AH could be classified as having an acute haemolytic transfusion reaction (AHTR) as per the definition provided by the Association of Veterinary Haematology and Transfusion Medicine's Transfusion Reaction Small Animal Consensus Statement.

METHODS

Medical records of cats that received canine packed red blood cells (PRBCs) between July 2018 and September 2020 at a veterinary hospital were reviewed. The incidence of AH, AHTRs, febrile non-haemolytic transfusion reactions (FNHTRs), transfusion-associated circulatory overload and septic transfusion reactions were recorded.

RESULTS

The medical records of 53 cats were retrospectively evaluated. Twenty-three (43%) cats had transfusion reactions. Thirteen (25%) cats had AH; however, only four (8%) met the definition of an AHTR. Ten (19%) cats were determined to have FNHTRs. Survival to discharge of cats affected by AH was 50% (25% for cases that met the definition of an AHTR). Survival to discharge of cats not suffering from AHTR was 40%.

CONCLUSIONS AND RELEVANCE

This report indicates that a higher proportion of cats undergo AH (25%) when administered canine PRBCs than previously reported, although many could not be classed as having an AHTR due to an apparently adequate packed cell volume rise. Challenges with sourcing feline blood in emergency situations occasionally necessitates the use of xenotransfusion in transfusion medicine. Clinicians should be aware that haemolysis after xenotransfusion can occur within 24 h and that a repeat feline transfusion may be required sooner than anticipated in some cases.

Do Blood Phenotypes of Feline AB Blood Group System Affect the SARS-CoV-2 Antibody Serostatus in Cats?

Cats are susceptible to coronavirus infections, including infection by human severe acute respiratory syndrome coronavirus (SARS-CoV). In human ABO system blood groups, alloantibodies can play a direct role in resistance to infectious diseases. Individuals with the AB blood type were over-represented in the SARS-CoV-2 infection group. Blood type AB individuals lack both anti-A and anti-B antibodies, and therefore lack the protective effect against SARS-CoV-2 infection given by these antibodies. Starting from this knowledge, this pilot preliminary study evaluated a possible association between feline blood phenotypes A, B, and AB and serostatus for SARS-CoV-2 antibodies in cats. We also investigated selected risk or protective factors associated with seropositivity for this coronavirus. A feline population of 215 cats was analysed for AB group system blood phenotypes and antibodies against the nucleocapsid (N-protein) SARS-CoV-2 antigen using a double antigen ELISA. SARS-CoV-2 seropositive samples were confirmed using a surrogate virus neutralization test (sVNT). Origin (stray colony/shelter/owned cat), breed (DSH/non DSH), gender (male/female), reproductive status (neutered/intact), age class (kitten/young adult/mature adult/senior), retroviruses status (seropositive/seronegative), and blood phenotype (A, B, and AB) were evaluated as protective or risk factors for SARS-CoV-2 seropositivity. Seropositivity for antibodies against the SARS-CoV-2 N-protein was recorded in eight cats, but only four of these tested positive with sVNT. Of these four SARS-CoV-2 seropositive cats, three were blood phenotype A and one was phenotype AB. Young adult age (1-6 years), FeLV seropositivity and blood type AB were significantly associated with SARS-CoV-2 seropositivity according to a univariate analysis, but only blood type AB (p = 0.0344, OR = 15.4, 95%CI: 1.22-194.39) and FeLV seropositivity (p = 0.0444, OR = 13.2, 95%CI: 1.06-163.63) were significant associated risk factors according to a logistic regression. Blood phenotype AB might be associated with seropositivity for SARS-CoV-2 antibodies. This could be due, as in people, to the protective effect of naturally occurring alloantibodies to blood type antigens which are lacking in type AB cats. The results of this pilot study should be considered very preliminary, and we suggest the need for further research to assess this potential relationship.

Alloimmunization in dogs after transfusion: A serial cross-match study

BACKGROUND

Cross-matching is performed to determine the serological compatibility of donor and recipient blood. Current guidelines recommend that cross-matching should be performed in dogs when an initial transfusion was performed more than 4 days ago or when the transfusion history is unknown.

HYPOTHESIS

Determination at what time point alloantibodies are detected in dogs after transfusion. The hypothesis was that dogs would form alloantibodies within 4 days after a transfusion.

ANIMALS

Twenty-one anemic dogs were transfused and monitored for at least 4 subsequent days. Exclusion criteria were persistent red blood cell (RBC) agglutination and a previous transfusion.

METHODS

Prospective observational study. Cross-matching was performed before the initial DEA 1-compatible transfusion and on days 1, 2, 3, and 4 and if possible, between day 5 and 28, using the tube method without enhancement (major cross-match, recipient controls); recipients were monitored for transfusion reactions.

RESULTS

In 12/21 dogs a positive cross-match (microscopic degree of agglutination [AD] 1+ to 2+) was observed within 4 days after the transfusion. In a nonlinear regression model, no significant association was detected between type of anemia (P = .41), RBC storage time (P = .44), immunosuppressive treatment (P = .75) nor transfusion volume (P = .70) and the occurrence of positive cross-matches within 4 days after transfusion. Another 4 dogs developed a positive cross-match (microscopic AD 1+ to 2+) after 6 to 13 days.

CONCLUSIONS AND CLINICAL IMPORTANCE

Because production of alloantibodies was detected as early as 1 day after transfusion, cross-matching should be performed before every subsequent transfusion.

Evaluation of Association between Blood Phenotypes A, B and AB and Feline Coronavirus Infection in Cats

Cats are susceptible to feline coronavirus (FCoV), a highly contagious virus with fecal–oral transmission. In people, susceptibility to coronavirus infection, such as SARS-CoV infection, has been associated with the ABO blood group, with individuals with blood group O having significantly lower risk of SARS-CoV infection. This study evaluated a possible association between feline blood group phenotypes A, B and AB and serostatus for antibodies against FCoV. We also investigated risk or protective factors associated with seropositivity for FCoV in the investigated population. Feline populations were surveyed for AB group system blood types and for presence of antibodies against FCoV. Blood phenotype, origin, breed, gender, reproductive status and age of cats were evaluated as protective or risk factors for coronavirus infection. No blood type was associated with FCoV seropositivity, for which being a colony stray cat (p = 0.0002, OR = 0.2, 95% CI: 0.14–0.54) or a domestic shorthair cat (p = 0.0075, OR = 0.2, 95% CI = 0.09–0.69) were protective factors. Based on results of this study, feline blood phenotypes A, B or AB do not seem to predispose cats to seropositivity for FCoV. Future studies on other feline blood types and other infections could clarify whether feline blood types could play a role in predisposing to, or protecting against, feline infections.

Evaluating the Possibility of Transfusion Medicine, Through Crossmatching in Juvenile Galapagos Sea Lions (Zalophus wollebaeki)

The Galapagos sea lion (Zalophus wollebaeki) is an endemic pinniped to the Galapagos archipelago, and like most wild mammals, is at risk for anemia due to trauma, infectious disease, and poor nutrition. This study evaluated the health status of 26 juvenile Galapagos sea lions on the island of San Cristobal prior to evaluating 100 crossmatch combinations. On evaluation, all but one sea lion had no major systemic abnormalities. Of the 100 crossmatches performed, 23% had minor reactions. The most significant reaction was weak macroscopic agglutination found in 4% of samples. The small percentage of agglutination reactions suggests a small proportion of naturally occurring alloantibodies in this species and may be consistent with a low risk of acute immune-mediated hemolytic transfusion reaction.

Characterization of post-transfusion anti-FEA 1 alloantibodies in transfusion-naive FEA 1-negative cats

Objectives

The aim of this study was to characterize anti-feline erythrocyte antigen (FEA) 1 alloantibodies following sensitization of FEA 1-negative cats, including their rate of appearance, agglutination titer over time and immunoglobulin class. A secondary aim was to obtain polyclonal anti-FEA 1 alloantibodies to increase the availability of FEA 1 blood typing. We also describe a case study documenting an acute hemolytic transfusion reaction in a transfusion-naive FEA 1-negative feline patient that received FEA 1-positive blood.

Methods

In this prospective clinical study, 35 cats with blood group type A underwent extensive blood typing for FEA 1–5. Two cats were identified as FEA 1-negative; these cats were transfused uneventfully with 50 ml of FEA 1-positive, but otherwise compatible, packed red blood cells. Post-transfusion blood samples were collected routinely as long as anti-FEA 1 alloantibodies were detected. Appearance of anti-FEA 1 alloantibodies was detected using a gel column crossmatch method.

Results

Anti-FEA 1 alloantibodies were detected as early as 5 days post-transfusion and remained detectable for over 400 days in one cat. Agglutination titers in both cats were relatively weak (1:1 to 1:8). The main immunoglobulin class was IgM.

Conclusions and relevance

Transfusion of FEA 1-negative, transfusion-naive cats with FEA 1-positive blood results in production of post-transfusion anti-FEA 1 alloantibodies as early as 5 days post-transfusion. Our results confirm the potential immunogenicity of FEA 1 and support crossmatching prior to a blood transfusion, even in transfusion-naive cats. Further studies are needed to better document the clinical importance of these post-transfusion antibodies, as well as to facilitate routine blood typing for the FEA 1 antigen in cats.

Xenotransfusion of Blood from Dog to Cat: Should Canine Blood Be Our First Choice for Feline Transfusion in Emergency Situations?

Despite the ability to determine feline blood types, the transfusion of canine blood to cats is still practiced in some countries. Xenotransfusion is effective—even if its effects only last for a few days—and is not associated with serious adverse effects. It avoids the need for blood typing, and most importantly, it avoids the transmission of intraspecific infectious agents, notably the feline leukemia virus (FeLV). Transfusion with canine blood is easier, quicker and less costly than transfusion with feline blood; it is less disagreeable for the donor. In the light of these arguments, when feline blood collected according to current guidelines is not available, in particular when the donor is not confirmed to be negative for the FeLV provirus, the authors consider it to be judicious to use canine blood for feline transfusion in emergency situations; this practice is preferable to inaction and to the inoculation of an infectious agent. Allotransfusion remains preferable in non-emergency situations as a treatment of chronic compensated anaemiae or if an appropriate donor (negative for FeLV provirus) is available. However, 2–4 days after a xenotransfusion, if a clinical alteration and a significant decrease in haematocrit are observed, a transfusion with cat’s blood confirmed to be negative for FeLV provirus should be performed. Xenotransfusion should never be used twice.

Awareness, Motivation, and Fear towards Canine Blood Donation-A Survey of Dog Owners in Lithuania

Simple Summary

Canine blood transfusions and blood donations are integral to veterinary medicine. Currently, the supply of canine blood products is not meeting the demand, and veterinarians find it difficult to recruit blood donors, especially when animal welfare is a priority. The general aim of our study was to determine how to improve the effectiveness of canine blood donor recruitment. To do this, we conducted a survey to identify the level of dog owners’ awareness about canine blood donation and to help us understand what would motivate people to become a part of the donation process as well as what people are afraid of. The results of our study suggest that donor recruitment could be increased by dispelling the myths about possible complications and by improving communication between veterinary doctors and dog owners, as the awareness of canine blood donation is poor. In conclusion, recruitment strategies should focus on the management of fear regarding canine blood donation, as well as animal welfare and the education of clients, as motivational strategies come second.

Abstract

The recruitment of canine blood donors remains a challenge, especially in countries where blood donation and veterinary medicine are still emerging medical fields. There are few previous studies that have discussed canine blood donation strategies, and the subject of fear and its influencing factors have not been investigated. The main purpose of our study was to investigate dog owners’ awareness, motivation, and fear regarding canine blood donation in order to improve donor recruitment strategies. We created a six-page questionnaire and submitted it to dog owners (n = 207) in person. Two-thirds of the respondents (65.7%) were not aware that canine blood donation exists in Lithuania. We did not find any factors that would significantly affect the motivation of respondents toward donation. We found an association between the fear of the owner and the health status of the owned dog (p = 0.008), as well as if their animal had needed urgent care in the past (p = 0.031). The fact that some participants were blood donors themselves did not affect their motivation, but they were 19.76% less afraid of canine blood donation (p = 0.001), as were respondents who were aware of canine blood donation (p = 0.004). In conclusion, the recruitment strategy should focus on the management of fear toward canine blood donation and the education of clients, and donor welfare must remain a priority.

Cross-sectional study of approaches to diagnosis and management of dogs with immune-mediated haemolytic anaemia in primary care and referral veterinary practices in the United Kingdom

OBJECTIVES

To determine whether veterinarians in primary care practices (PCPs) and board-certified clinicians (BCCs) approach treatment of dogs with immune-mediated haemolytic anaemia (IMHA) similarly, and whether practitioners with more experience treat similarly to those with less experience. We hypothesised those in PCPs would show more variation in their approach to similar cases than BCCs.

METHODS

A cross-sectional study was conducted by distributing a questionnaire to BCCs and veterinarians in PCPs. The questionnaire included direct questions and a number of clinical scenarios intended to capture approaches to common treatment problems.

RESULTS

Questionnaire responses were received from 241 veterinarians, including 216 in PCPs and 25 BCCs. Veterinarians in both settings used similar tests for diagnosis of IMHA, but BCCs performed more tests to exclude underlying causes of 'associative' disease. All veterinarians reported use of similar initial dosages of glucocorticoids (median 2 mg/kg per day in both groups, p = 0.92) but those used by more experienced practitioners were higher than those with less experience. Most veterinarians made allowances for the weight of dogs, using lower prednisolone dosages in a clinical scenario involving a 40 kg dog compared to a 9 kg dog (p = 0.025 for PCP, p = 0.002 for BCC). BCCs reported greater use of combinations of immunosuppressive drugs (p<0.0001) and of antithrombotic drugs (p<0.0001); use of antithrombotic drugs was also less common among more experienced practitioners compared to less experienced.

CONCLUSIONS

Approaches to treatment of dogs with IMHA differ between BCCs and those in PCP. These differences may affect design and implementation of future research studies and clinical guidelines.

Effect of Leukoreduction by Pre-Storage Filtration on Coagulation Activity of Canine Plasma Collected for Transfusion

Leukoreduction of blood products is a technique used to prevent leukocyte-induced transfusion reactions and is extensively used in human, but rarely in veterinary patients. The concentration of some coagulation proteins can be affected by the processing steps used for the preparation of leuko-reduced plasma units. In this study, we assessed the effect of leukoreduction on coagulation activity of canine plasma collected for transfusion. Ten plasma units, five obtained from non-leuko-reduced (non-LR) whole blood (WB) units and five from leuko-reduced (LR) WB units were evaluated. Prothrombin time (PT), activated partial thromboplastin time (aPTT), coagulation factor activities of factors (F) V, VIII, X, XI, and von Willebrand (vWF), fibrinogen and D-dimers content were assessed at collection (baseline value, D0) and after 7 days of frozen storage at −18 °C (D7). Compared to non-LR plasma units, LR units showed a statistically significant prolonged aPTT and reduced FXI activity. Filtration had no significant effect on the other factors and parameters evaluated. Filtration-dependent changes appear to have no impact on the therapeutic quality of plasma obtained from leuko-reduced whole blood, other than for FXI activity. Further studies on a larger sample size comparing the same unit before and after leukoreduction are needed to confirm these findings.