Feline blood transfusions: A pinker shade of pale

Intravenous fluid therapy compared to no treatment following blood donation in cats: a randomised controlled trial

OBJECTIVES

There is currently no consensus regarding the use of intravenous fluid therapy in feline patients post-blood donation in veterinary medicine. The primary aim of this study was to determine whether blood donation can be performed safely without post-donation intravenous fluid therapy. The secondary aim was to report owner-noted post-donation changes.

MATERIALS AND METHODS

The study aimed to enrol 100 conscious feline blood donations by client-owned cats performed at a veterinary teaching hospital. Donors were randomised to either receive intravenous compound sodium lactate (twice the volume of blood donated over 2 hours) immediately after blood donation, or to receive no post-blood donation intravenous fluid therapy. Systolic blood pressure was measured non-invasively at 0, 60 and 120 minutes post-donation. Median blood pressures were compared between the two groups using a Shapiro-Wilk test. Owners were called the day following the donation to collect information on changes in their cat post-donation.

RESULTS

One hundred cats were enrolled and the data of 97 cats were analysed; 46 who received intravenous fluid therapy and 51 who did not. Mean donation volume was 9.95 mL/kg for the intravenous fluid therapy group and 9.72 mL/kg for the non-intravenous fluid therapy group. At each time point, the median blood pressure did not differ significantly between the two groups. The main reported changes in both goups were bruising at the venepuncture site with 27.3% (12/44) in the IVFT group and 23.4% (9/37) in the no-IVFT group, and mild lethargy up to a maximum of 24 hours post donation with 11.4% (5/44) in the IVFT group and 18.9% (7/37) in the no-IVFT group.

CLINICAL SIGNIFICANCE

This study suggests that the use of intravenous fluid therapy post-feline blood donation may not be necessary. This could mean reduced hospitalisation time for feline donors, possibly decreasing feline stress.

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.

NONDOMESTIC FELID ABC BLOOD PHENOTYPING, GENOTYPING, AND CROSSMATCHING

Based upon previous clinical experience with domestic cats (Felis catus), the ability to assess ABC blood types and blood (in-)compatibilities of nondomestic felids, and adequately consider and plan for blood transfusions, may be important. Although nondomestic felids appear to have an ABC blood group system similar to domestic cats, typing with point-of-care kits and by CMAH genotyping for domestic cats have not been reported. In this study, 162 blood samples from 18 different nondomestic felid species (cheetah [Acinonyx jubatus, n = 42], lion [Panthera leo, n = 33], tiger [Panthera tigris, n = 23], Canada lynx [Lynx canadensis, n = 11], snow leopard [Uncia uncia, n = 10], puma [Puma concolor, n = 7], clouded leopard [Neofelis nebulosa, n = 6], serval [Leptailurus serval, n = 5], jaguar [Panthera onca, n = 5], fishing cat [Prionailurus viverrinus, n = 4], Pallas cat [Felis manul, n = 3], bobcat [Lynx rufus, n = 3], ocelot [Leopardus pardalis, n = 3], black footed cat [Felis nigripes, n = 2], leopard [Panthera pardus, n = 2], African wildcat [Felis lybica, n = 1], caracal [Caracal caracal, n = 1], and sand cat [Felis margarita, n = 1]) were ABC blood typed by laboratory and point-of-care tests, genotyped for four known CMAH variants for type B and type C (AB) phenotypes, and crossmatched with one another and domestic type A cats. Traditional tube typing identified blood type A (n = 106), type B (n = 8), type C (n = 43), and no discernible ABC type (n = 4). Several discrepancies were found between point-of-care and traditional typing test results. None of the tested felids possessed the four CMAH variants responsible for type B and C (AB) in domestic cats. Crossmatch incompatibilities (≥2+ agglutination) were identified within and between nondomestic felid species and beyond ABC incompatibilities. Of 26 crossmatches performed between domestic cats and various nondomestic felids, only 7 (27%) were compatible. In conclusion, point-of-care typing kits and CMAH genotyping, successfully used in domestic cats, may not identify the correct ABC blood type in nondomestic felids. Prior crossmatching is recommended to increase the likelihood of compatible transfusions between any nondomestic felids.

Successful autologous transfusion from the subcutaneous space in a domestic shorthair cat with suspected anticoagulant rodenticide toxicity

Case summary

A 6-month-old female entire domestic shorthair cat was presented with a 4-day history of progressive swelling over the dorsal cranium. Subsequent diagnostics revealed a large haematoma, a secondary haemostatic defect and a moderate anaemia. The owner disclosed access to multiple brodifacoum bait stations. The anaemia and haematoma progressed despite treatment with fresh frozen plasma and phytonadione and the cat developed signs of haemorrhagic shock. Allogenic transfusion was declined due to cost and 18 ml of blood was aspirated from the haematoma and transfused. The cat stabilised quickly and was discharged the next day with oral phytonadione.

Relevance and novel information

Autologous transfusion from the subcutaneous space has not been previously reported. It was well tolerated and life-saving in this case.

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.

Effect of microaggregate filter passage on feline whole blood stored for 35 days

OBJECTIVES

The aim of this study was to compare the characteristics of fresh and stored feline red blood cells (RBCs) after passage through an 18 μm microaggregate filter.

METHODS

Nine cats were recruited for a single blood donation using an open collection system. A simulated transfusion using a syringe driver and microaggregate filter was performed over 2 h with half the blood on the day of donation and the other half after 35 days of storage. Differences in haematological parameters, haemolysis percentage and osmotic fragility (OF) were compared on the day of donation pre-filter passage (D0-) vs day of donation post-filter (D0+) or day 35 storage pre-filter (D35-) and post-filter (D35+). Blood was cultured at D0+ and D35+.

RESULTS

There were no statistically significant differences in the D0- vs D0+ comparisons. There were statistically significant (P <0.05) increases in haemolysis percentage, red cell distribution width (RDW) percentage and mean OF, and decreases in packed cell volume (PCV), RBC count, haemoglobin and haematocrit for D0- vs D35-. The same was found for D0- vs D35+ with the addition of a significant increase in mean cell haemoglobin (MCH). For D35- vs D35+ only MCH significantly increased. At day 35, 6/9 units had haemolysis percentages that exceeded 1%. This increased to 8/9 of stored units post-filter passage. All blood units cultured negative.

CONCLUSIONS AND RELEVANCE

Fresh RBCs exhibited no in vitro evidence of injury following passage through an 18 μm microaggregate filter. Increased MCH was observed in the stored blood and may represent haemolysis induced by the filter. All other changes can be explained by storage lesion rather than filter passage. The findings highlight the importance of blood banking quality controls and the need for further research to assess the effects of transfusion technique, specifically filter passage, on storage lesion-affected feline blood.

Quantitative assessment of infusion pump-mediated haemolysis in feline packed red blood cell transfusions

OBJECTIVES

Haemolysis caused by the use of peristaltic infusion pumps (PIPs) has been described in human and canine packed red blood cells (pRBCs). The aim of this study was to evaluate the effects of two different linear PIPs on the haemolysis of feline pRBC units stored for a long time.

METHODS

Feline pRBC units stored with adenine, dextrose, mannitol and sodium chloride (SAGM) were manufactured. After 35-42 days of storage at 2-4°C, a line administration system with a 180 µm filter was attached to every pRBC bag, the system was drained by gravity alone (8 drops/min) and a 1.3 ml sample was collected (G). A NIKI V4 pump was then used at a flow rate of 25 ml/h, the flow was stopped when the infusion system was filled with blood coming from the infusion pump and another 1.3 ml sample was collected (NK). Finally, an Infusomat FmS pump was evaluated, collecting another 1.3 ml sample (IM). Packed cell volume (PCV) was measured in all samples by microhaematocrit centrifugation, total haemoglobin (HGB) was measured using a specific haemoglobin analyser and, after centrifugation, free HGB was determined by spectrophotometry. The percentage of haemolysis was calculated. Friedman's test was used to compare the samples.

RESULTS

Fifteen feline pRBC units were evaluated. The average degree of haemolysis for sample G (gravity-assisted) was 1.12%. Comparison of the degree of gravity-assisted haemolysis with haemolysis in PIP NK (1.13%) and IM (1.14%) samples revealed no significant differences, with differences of only 0.01% and 0.02%, respectively.

CONCLUSIONS AND RELEVANCE

The results of this study demonstrate that the use of two common PIPs in veterinary hospitals does not produce levels of haemolysis that are significantly different than that caused by gravity alone during transfusion of feline pRBCs at a rate of 25 ml/h.

Investigation of biomarkers for impending fluid overload in a feline acute haemorrhage-resuscitation model

OBJECTIVE

To determine biomarkers for impending fluid overload during intravenous fluid administration in a feline haemorrhage-resuscitation model.

STUDY DESIGN

Randomized crossover study.

ANIMALS

A group of six domestic cats (mean age and weight: 21 months; 4.9 kg, respectively).

METHODS

The cats underwent three treatments, 2 months apart. They were anaesthetized and instrumented to measure a range of physiological, blood gas, haematological and biochemical variables over time. Samples were taken during a health check, before haemorrhage, after haemorrhage and then at 30 minute intervals during fluid resuscitation and 24 hours later. The three treatments were: 1) control, sham haemorrhage and resuscitation; 2) lactated Ringer's solution (LRS); and 3) 6% tetrastarch 130/0.4 (Vol) where the cats underwent a controlled haemorrhage then resuscitation by administering LRS and Vol at 60 and 20 mL kg^-1 hour^-1, respectively, for 120 minutes. Fluid overload was identified by nasal discharge and radiographic evidence. Biomarkers were variables that exceeded the reference interval for cats during treatment. Potential biomarkers were analysed using receiver operating characteristic curves (p < 0.05).

RESULTS

Mean ± standard deviation total blood loss was 10.2 ± 2.3, 29.3 ± 9.0 and 29.1 ± 6.3 mL kg^-1 for control, LRS and Vol, respectively. The total volume of LRS and Vol administered was 120 and 40 mL kg^-1, respectively. Haematocrit, albumin, magnesium, chloride-to-sodium ratio and sodium-chloride difference were identified as potential biomarkers. These variables exceeded the reference intervals from 30 minutes of resuscitation onwards. A chloride-to-sodium ratio > 0.84 was the most sensitive (90%) and specific (75%) of all potential biomarkers.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in physiological variables, haematocrit and albumin were poor biomarkers of impending fluid overload compared with electrolytes. Finding the ideal biomarker to identify impending fluid overload of commonly used intravenous fluids should improve the safety of their administration in cats.

2021 ISFM Consensus Guidelines on the Collection and Administration of Blood and Blood Products in Cats

PRACTICAL RELEVANCE

Blood and blood products are increasingly available for practitioners to use in the management of haematological conditions, and can be lifesaving and therapeutically useful for patients with anaemia and/or coagulopathies. It is important for feline healthcare that donors are selected appropriately, and transfusions of blood or blood products are given to recipients that will benefit from them. Complications can occur, but can be largely avoided with careful donor management and recipient selection, understanding of blood type compatibility, and transfusion monitoring.

CLINICAL CHALLENGES

Feline blood transfusion, while potentially a lifesaving procedure, can also be detrimental to donor and recipient without precautions. Cats have naturally occurring alloantibodies to red cell antigens and severe reactions can occur with type-mismatched transfusions. Blood transfusions can also transmit infectious agents to the recipient, so donor testing is essential. Finally, donors must be in good health, and sedated as appropriate, with blood collected in a safe and sterile fashion to optimise the benefit to recipients. Transfusion reactions are possible and can be mild to severe in nature. Autologous blood transfusions and xenotransfusions may be considered in certain situations.

EVIDENCE BASE

These Guidelines have been created by a panel of authors convened by the International Society of Feline Medicine (ISFM), based on available literature. They are aimed at general practitioners to provide a practical guide to blood typing, cross-matching, and blood collection and administration.

Comparison of a closed system and an open system for blood collection in feline donors

OBJECTIVES

This research aimed to evaluate the performance of a closed blood collection system and to compare it with an open system in terms of feasibility, tolerability by the donor, quality of blood collected and bacterial contamination.

METHODS

Eight feline blood donors were prospectively and randomly subjected to both collection methods. Heart rate (HR), respiratory rate (RR) and blood pressure (BP) were evaluated before sedation, after sedation and after blood collection. The duration of the donation, the formation of a hematoma, and the degree of hemolysis and packed cell volume (PCV) of each blood unit were evaluated. Aliquot samples were aseptically collected from each unit and tested for bacterial contamination by culture and PCR on days 0, 14 and 28 of storage.

RESULTS

There was no significant difference between collection methods for HR and RR at any time point. Before sedation, the mean systolic BP was significantly higher with the closed system (closed 169 mmHg, open 137 mmHg; P = 0.003). The average duration of collection was significantly shorter with the closed system (closed 3 mins 10 s, open 8 mins; P = 0.035); however, the prevalence of a successful blood collection with a single venipuncture and hematoma formation were not significantly different between systems. The mean unit PCV was significantly higher with the open system (closed 31%, open 34%; P = 0.026). On bacterial culture, 15/16 units were negative at all time points (closed 7; open 8). Using PCR, 5/16 units were positive for Ralstonia species for at least one time point (closed 3; open 2).

CONCLUSIONS AND RELEVANCE

Our designed closed system appears to be well adapted to feline blood collection and was well tolerated by the donors, performing similarly to an open system, and could represent a valuable clinical device for the development of a feline blood bank, namely feline blood storage.

Current fluid and blood product availability in veterinary setting: a survey of UK small animal practices

OBJECTIVES

To investigate and discuss current fluid and blood products stocked in small animal practices in the UK.

METHODS

An online survey was circulated to small animal veterinary practices across the UK. The survey included questions regarding the level of hospital care provided, the type of fluid and blood component products stocked, the most frequently restocked products, and the available options in the event that blood products were required but not stocked.

RESULTS

There were 423 responses including 27 duplicates. The remaining 396 respondents represented a spectrum of practices including 19 referral practices. Crystalloids were stocked in all practices. Lactated Ringer's solution was the most frequently re-stocked product in 355 of 396 (90%) of practices. Where synthetic colloids were stocked, gelatin-based colloids (155/178 [87%]) were stocked in preference to hydroxyethyl starches (23/178 [13%]). Blood products were stocked by 81 of 396 (20%) of practices. If a blood product was required but not stocked, 31% of practices would use a pet blood banking service, 28% would use their own blood donors, and 21% would refer.

CLINICAL SIGNIFICANCE

This study provides an insight into the fluid and blood products stocked and used by a selection of veterinary practices within the UK and serves as a baseline for ongoing research and decision-making in both veterinary practice and industry.

Retrospective evaluation of fresh frozen plasma use in 121 cats: 2009-2016

OBJECTIVES

To document indications for fresh frozen plasma (FFP) use in cats, doses administered, and frequency of adverse transfusion reactions (ATR).

DESIGN

Retrospective observational study from January 2009 to November 2016.

SETTING

Large urban referral and emergency facility.

ANIMALS

One hundred twenty-one client-owned cats that received FFP.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Signalment, indication(s), dose, pre- and posttransfusion total plasma protein, prothrombin time, activated partial thromboplastin time, as well as possible ATR, primary disease process, and outcome were recorded. Doppler blood pressure was increased posttransfusion (mean pre 99.5 ± 30.8 mm Hg; post 108.5 ± 32.5 mm Hg, P = .027). Cats were significantly less likely to be coagulopathic posttransfusion (P < 0.001). Most common indications were suspected coagulopathy (n = 105, 83%), hemorrhage (n = 45, 35%), and hypotension (n = 32, 25%). Median dose was 6 mL/kg (interquartile range = 3 mL/kg) and was negatively correlated with body weight (r = -.598, P < 0.001). Possible ATR occurred in 17 of 108 (16%, 95% confidence interval [CI], 10-24%) of transfusions. Increased body temperature was most common in 11 of 108 (10%, 95% CI, 5-18%), followed by tachypnea/dyspnea in 8 of 108 (7%, 95% CI, 3-13%). Common primary disease processes included liver disease (n = 41, 34%), neoplasia (n = 19, 16%), and sepsis (n = 15, 12%). Overall mortality was 54%. Improvement of clotting times was associated with increased odds of survival (odds ratio = 2.4; 95% CI, 1.1-5.3; P = 0.023).

CONCLUSIONS

Clinician justifications for FFP transfusions are comparable to that reported in dogs; however, the mL/kg dose is lower. Coagulopathy and blood pressure significantly improve posttransfusion. Possible ATR were as frequent as that reported with feline packed RBCs transfusions and classified as mild.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS AND RELEVANCE

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

Prospective evaluation of the utility of cross-matching prior to first transfusion in cats: 101 cases

OBJECTIVES

To: (1) assess the frequency of crossmatch incompatibility in naïve feline blood transfusion recipients using two crossmatching methods, (2) measure the effect of crossmatch incompatibility on change in packed cell volume following transfusion, (3) assess the frequency of acute transfusion reactions and errors in blood transfusions in cats and (4) assess the impact of crossmatch incompatibility on the likelihood of transfusion reactions.

MATERIALS AND METHODS

Cats being administered a first AB-matched transfusion in a veterinary teaching hospital were prospectively recruited for this observational study. A slide agglutination method and a commercial test were both used for major and minor crossmatching. We measured increase in packed cell volume at 12 hours after transfusion relative to the mass of red blood cells given per recipient bodyweight and recorded transfusion reactions.

RESULTS

A total of 101 cats was included. Crossmatch incompatibility was common using the slide agglutination method (27% and 10% major and minor incompatibility, respectively), but less common with the commercial test (major and minor incompatibility both 4%). Crossmatch incompatibility with any method was not associated with less effective transfusion in terms of change in packed cell volume. Transfusion reactions occurred in 20 cats, most commonly febrile non-haemolytic transfusion reactions (n = 9) and haemolytic transfusion reactions (n = 7). The commercial test appeared to be most specific for predicting haemolytic transfusion reactions.

CLINICAL SIGNIFICANCE

Transfusion reactions were fairly common but not associated with increased mortality. Use of crossmatch-compatible blood did not lead to a greater increase in PCV at 12 hours. The commercial test may predict a haemolytic transfusion reaction.

Xenotransfusion of canine blood to cats: a review of 49 cases and their outcome

OBJECTIVES

To describe the use of a xenotransfusion protocol, the outcome of xenotransfusion in recipient cats and to assess owner memory of the xenotransfusion.

MATERIALS AND METHODS

Cats administered xenotransfusions in two hospitals between January 2016 and July 2018 were included. Adherence to xenotransfusion protocol, cause of anaemia, blood type, packed cell volume (PCV), transfusion volume, transfusion reactions, PCV 12 hours after transfusion and survival to discharge were recorded. Owners of surviving cats were questioned to assess if they remembered that a xenotransfusion had been performed.

RESULTS

Forty-nine cats underwent the xenotransfusion protocol. The most common causes of anaemia were surgical blood loss (n = 17), immune-mediated haemolytic anaemia (n = 14) and neoplasia (n = 14). Median PCV before transfusion was 10%. Six cats (12%) had febrile non-haemolytic transfusion reactions. Median PCV 12 hours after transfusion was 25%. Ten cats (20%) died or were euthanased within 24 hours of xenotransfusion. A delayed haemolytic transfusion reaction occurred in 25 of 39 (64%) cats manifesting as icterus in 15 cats after a median of 1.9 days and haemolytic serum in 19 cats after a median of 2 days. Of the 18 cats alive at 1 week after discharge, 15 (83%) were still alive at a median of 173 days after xenotransfusion. All owners contacted remembered that their cats had received a xenotransfusion.

CLINICAL SIGNIFICANCE

Xenotransfusion of canine packed red blood cells to cats is possible but haemolysis should be expected between 1 and 6 days after transfusion.

Feline non-regenerative anemia: Diagnostic and treatment recommendations

PRACTICAL RELEVANCE

Non-regenerative anemia, or anemia with reticulocytopenia, is a daily diagnosis in feline practice.

CLINICAL CHALLENGES

The disease processes underlying non-regenerative anemia are many and diverse. A major diagnostic evaluation may be required to correctly diagnose and treat the underlying cause.

AUDIENCE

All veterinarians caring for cats will face the diagnostic and therapeutic challenge of non-regenerative anemia. Readers will benefit from the review of diagnostic testing and therapeutic options for non-regenerative anemia.

EVIDENCE BASE

This review summarizes the currently available literature informing diagnostic and treatment recommendations related to non-regenerative anemia. The evidence available to support the recommendations in this review is graded as low and includes predominantly expert opinion, case reports and cases series, on which the authors' interpretation/consensus is based.

Naturally occurring antibodies in cats against dog erythrocyte antigens and vice versa

Objectives The aim of this study was to investigate the presence of naturally occurring antibodies against canine erythrocyte antigens in cats and vice versa. The influence of canine and feline blood type on cross-match results was also studied. Methods Blood samples from 34 cats and 42 dogs were used to perform test tube major and minor cross-match tests and blood typing. Blood from each cat was cross-matched with blood from 2-6 dogs, for a total of 111 cross-match tests. Haemolysis, macro- and microagglutination were considered markers of a positive cross-match. Results Eighty-three overall major cross-match tests were positive at 37°C, 86 at room temperature and 90 at 4°C. The minor cross-match tests were positive in all but two cross-matches performed at 37°C, all tests performed at room temperature and all but one test performed at 4°C. No cats tested totally negative at both major and minor cross-matches performed with samples from any single dog. Prevalence of warm natural antibodies against canine erythrocyte antigens was lower in type B cats than in type A cats, regardless of the blood type of donor dogs. Conclusions and relevance This study reveals a high prevalence of naturally occurring antibodies in cats against dog erythrocyte antigens and vice versa, and suggests that transfusion of cats with canine blood is not recommended as a routine procedure owing to the potential high risk of either acute severe or milder transfusion reactions.

In vitro quality control analysis after processing and during storage of feline packed red blood cells units

BACKGROUND

During the storage of packed red blood cells (pRBC), packed cell volume (PCV), bacterial contamination and percentage of haemolysis [percentage of free haemoglobin (HGB) in relation to the total HGB] are important quality parameters. Both PCV and haemolysis are indicators of the cellular integrity of stored units. There are no published experimental studies that evaluated these parameters during storage of feline pRBC using SAGM (adenine, dextrose, mannitol and sodium chloride) as the additive solution. The present study aims to (1) evaluate the quality of feline pRBCs stored in SAGM; (2) test for the semi-closed system's suitability for use and risk of bacterial contamination; (3) establish the maximum storage time that may be appropriate to meet the criteria established by the United States Food and Drug Administration (US-FDA) guidelines for human blood banking; and (4) evaluate the need to calculate the percentage of haemolysis prior to the administration of units stored for more than 4 weeks. Four hundred eighty nine feline pRBC units were analyzed. Bacterial culture, PCV and percentage of haemolysis were determined within 6 h after processing (t0). One hundred and eighty units were re-tested for haemolysis and PCV after 29-35 days of storage (t1) and 118 units after 36-42 days (t2).

RESULTS

Bacterial contamination was not detected in any pRBC unit. Mean PCV at t0 was 52.25% (SD: ±5.27) and decreased significantly (p < 0.001) during storage to 48.15% (SD: ±3.79) at t1 and to 49.34% (SD: ±4.45) at t2. Mean percentage of haemolysis at t0 was 0.07% (SD: ±0.06) and increased significantly (p < 0.001) to 0.69% (SD: ±0.40) at t1 and to 0.81% (SD: ±0.47) at t2. In addition, 13.88% and 19.49% of pRBC units exceeded 1% haemolysis at t1 and t2, respectively.

CONCLUSIONS

According to the US-FDA guidelines for human blood banking that recommend a maximum of 1% haemolysis, the results of this study show that all feline pRBC units with less than 24 h of shelf life have low levels of haemolysis. However, units preserved up to 28 days can only be administered if tested for haemolysis before use, since 13.88% units exceeded the 1% limit. The semi-closed system was considered safe for use as bacterial contamination was not detected in any pRBC unit.

Alloimmunisation in transfused patients: serial cross-matching in a population of hospitalised cats

Objectives Cross-matching is currently recommended as part of pre-transfusion testing for repeat transfusions in cats 4 days after having received an initial transfusion. This prospective study determined when and if cats developed positive cross-match (CM) results after having been transfused with AB-compatible blood. Methods Donors were selected according to standard transfusion safety protocols. Twenty-one hospitalised anaemic recipients (blood type A: n = 20; blood type B: n = 1) received 1-4 (median 2) whole blood transfusions (WBTs) over 1-6 days (median 2) in 33 transfusion instances. The tube CM method, including major, minor and recipient control, was employed. Macroscopic and microscopic agglutination reactions were evaluated according to a predetermined scale. CM tests with a positive recipient control could not be evaluated. Results No signs of an acute transfusion reaction were observed. A total of 63 CMs were performed. In one cat with immune-mediated haemolytic anaemia the CM could not be evaluated (positive recipient control). The minor CM was negative in all cases. Fifteen of 20 cats had a negative major CM (MCM) 1-12 days (median 5) after their first transfusion. A positive MCM was observed in five cases after 2-10 days (median 5) post-first WBT. These five cats had received a total of 1-4 (median 2) WBTs. Cats with a negative MCM had received 1-3 (median 2) WBTs. In 51.5% (17/33) of transfusion instances, the cat's haematocrit increased as expected, with cats with a positive MCM at 40% (4/10) vs 56.5% (13/23) if MCM was negative. Conclusions and relevance Twenty-five percent (5/20) of the feline recipients likely developed alloantibodies against erythrocyte antigens outside of the AB system as early as 2 days post-first WBT. This adds data to the recommendation to include cross-matching in pre-transfusion screening tests.

Distribution of feline AB blood types: a review of frequencies and its implications in the Iberian Peninsula

Objectives

The objective of this study was to document the prevalence of feline blood types in the Iberian Peninsula and to determine the potential risk of incompatibility-related transfusion reactions in unmatched transfusions and the potential risk of neonatal isoerythrolysis (NI) in kittens born to parents of unknown blood type.

Methods

Blood samples were obtained from blood donors of the Animal Blood Bank (BSA-Banco de Sangue Animal). Blood typing was performed using a card method (RapidVet-H Feline Blood Typing; MDS).

Results

The studied population comprised 1070 purebred and non-purebred cats from Portugal and Spain aged between 1 and 8 years. Overall, frequencies of blood types A and B were 96.5% and 3.5%, respectively. No AB cats were found. Based on these data, the potential risks of NI and transfusion reactions in unmatched transfusions were calculated to be 6.8% and 2.8%, respectively.

Conclusions and relevance

Unlike previous studies, no type AB cats were found in this study. Although the calculated potential risks of transfusion reaction in unmatched transfusions and neonatal isoerythrolysis were low, blood typing prior to blood transfusion and blood typing of cats for breeding purposes are highly recommended.

Retrospective evaluation of unexpected events during collection of blood donations performed with and without sedation in cats (2010-2013)

OBJECTIVES

Describe unexpected events (UEs) that occurred during blood donation in cats with and without sedation.

DESIGN

Retrospective observational study (2010-2013).

SETTING

University teaching hospital.

ANIMALS

Client-owned healthy cats enrolled in a blood donation program.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood collection for transfusion was performed 115 times from 32 cats. Seventy donation events were in unsedated cats and 45 in sedated cats. For each collection, the anticipated blood volume to be collected, actual blood volume collected, sedation protocol, and any UE in the peridonation period were recorded. There were 6 categories of UEs: movement during donation, donor anxiety, inadequate collected blood volume, jugular vessel related UEs, additional sedation requirement, and cardiorespiratory distress. Fisher's exact test was used to compare the frequency of UEs between sedated and unsedated cats. UEs were recorded in 54 of 115 collections. In the donor population, movement was reported as an UE in 0 cats that donated under sedation and 24/70 (34.3%) cats that donated without sedation (P < 0.001). Donor anxiety occurred in 2/45 (4.4%) cats that donated under sedation and 14/70 (20.0%) cats that donated unsedated (P = 0.014). Unsedated donation did not increase the likelihood of inadequate donation volume, jugular vessel related UEs, or cardiorespiratory distress. Eight of 45 (17.8%) sedated donations required additional sedation.

CONCLUSIONS

Movement during donation and signs of donor anxiety were more frequent in unsedated cats. These were considered minor issues, expected in unsedated cats being gently restrained. Blood collection from unsedated feline donors is a viable alternative to sedated donation.

Blood Transfusions in Dogs and Cats Receiving Hemodialysis: 230 Cases (June 1997-September 2012)

Background

Multiple factors exist that contribute to anemia in dogs and cats receiving hemodialysis, can necessitate transfusion.

Objectives

To describe blood product usage in dogs and cats with acute and chronic kidney disease that were treated with intermittent hemodialysis to determine risk factors associated with the requirement for blood product transfusion.

Animals

83 cats and 147 dogs undergoing renal replacement therapy at the Animal Medical Center for acute or chronic kidney disease.

Methods

Retrospective medical record review of all dogs and cats receiving renal replacement therapy for kidney disease, from June 1997 through September 2012.

Results

Blood products (whole blood, packed RBCs, or stromal‐free hemoglobin) were administered to 87% of cats and 32% of dogs. The number of dialysis treatments was associated with the requirement for transfusion in cats (adjusted OR 2.21, 95% CI 1.13, 4.32), but not in dogs (adjusted OR 0.98, 95% CI 0.95, 1.03). Administration of a blood product was associated with a higher likelihood of death in dogs (OR 3.198, 95% CI 1.352, 7.565; P = .0098), but not in cats (OR 1.527, 95% CI 0.5404, 4.317, P = .2).

Conclusions and Clinical Importance

Veterinary hospitals with a hemodialysis unit should have reliable and rapid access to safe blood products in order to meet the needs of dogs and cats receiving dialysis.

Exploring the Possibility of Cryopreservation of Feline and Canine Erythrocytes by Rapid Freezing with Penetrating and Non-Penetrating Cryoprotectants

Efficient application of veterinary blood transfusion approaches for small companion animals requires readily available supply of the donor material. This can be achieved by developing of effective biobanking technologies allowing long-term storage of donor blood components via cryopreservation. Transfusion of an erythrocyte concentrate allows the successful correction of various hematological pathologies, severe bleeding, and etc. While in the past there were several approaches to cryopreserve red blood cells of dogs, to our knowledge there is virtually no data on cryopreservation of feline erythrocytes. In this paper, we performed a comprehensive parameter optimization for low temperature storage of RBCs of both species. Here, the efficiency of single-component and multicomponent cryoprotective media as well as necessary time of pre-incubation with penetrating and non-penetrating cryoprotectants prior to rapid freezing is analyzed. This study showed that glycerol was not sufficient for cryopreservation of red blood cells of the studied species under the investigated conditions. Application of 10% (v/v) ME2SO allowed for a significant reduction of canine and feline erythrocytes hemolysis after thawing. 17.5% hydroxyethyl starch demonstrated the highest cryoprotective activity for both species. It was found that dog RBCs should be incubated in cryoprotective media for 30 min at 22°C prior to freezing, while for cat RBCs 20 min is sufficient. Combination of CPAs was less effective. Presented data may be considered in further studies in veterinary transfusion and blood banking optimization.

FREQUÊNCIAS DOS TIPOS SANGUÍNEOS E TÍTULOS DOS ALOANTICORPOS EM FELINOS DOMÉSTICOS

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

Hospital-acquired Anemia in Critically Ill Dogs and Cats: A Multi-Institutional Study

BACKGROUND

Hospital-acquired anemia is commonly described in people but limited information currently is available regarding its prevalence in animals.

HYPOTHESIS/OBJECTIVES

Assess the prevalence of hospital-acquired anemia in hospitalized critically ill dogs and cats, and examine its relationship with phlebotomy practices, transfusion administration, and survival to discharge.

ANIMALS

Eight hundred and fifty-one client-owned animals (688 dogs and 163 cats).

METHODS

A multicenter, observational study was conducted in which packed cell volume (PCV) was recorded at the time of admission and on subsequent hospitalization days. Signalment, number of blood samples obtained, underlying disease, whether or not blood products were administered, duration of hospitalization, and survival to discharge were recorded.

RESULTS

Admission anemia prevalence was 32%, with overall prevalence during the hospitalization period of 56%. The last recorded PCV was significantly lower than the admission PCV for both dogs (admission PCV, 42% [range, 6-67%]; last recorded PCV, 34% [range, 4-64%], P < .0001) and cats (admission PCV, 31% [range, 6-55%]; last recorded PCV, 26% [range, 10-46%], P < .0001). Patients that developed anemia had significantly more blood samples obtained (nonanemic, 5 blood samples [range, 2-54]; anemic, 7 blood samples [range, 2-49], P < .0001). Hospitalized cats were significantly more likely to develop anemia compared to dogs (P < .0001), but anemic dogs were significantly less likely to survive to discharge (P = .0001). Surgical patients were at higher risk of developing hospital-acquired anemia compared to medical patients (OR, 0.63; 95% CI, 0.4-0.9; P = .01).

CONCLUSIONS AND CLINICAL RELEVANCE

Hospital-acquired anemia occurred frequently, especially in surgical patients. Additional studies focused on the direct effect of phlebotomy practices on the likelihood of anemia development in hospitalized animals are warranted.

Retroviral DNA--the silent winner: blood transfusion containing latent feline leukemia provirus causes infection and disease in naïve recipient cats

Background

The feline leukemia virus (FeLV) is a gamma-retrovirus of domestic cats that was discovered half a century ago. Cats that are infected with FeLV may develop a progressive infection resulting in persistent viremia, immunodeficiency, tumors, anemia and death. A significant number of cats mount a protective immune response that suppresses viremia; these cats develop a regressive infection characterized by the absence of viral replication and the presence of low levels of proviral DNA. The biological importance of these latter provirus carriers is largely unknown.

Results

Here, we demonstrate that ten cats that received a transfusion of blood from aviremic provirus carriers developed active FeLV infections, some with a progressive outcome and the development of fatal FeLV-associated disease. The infection outcome, disease spectrum and evolution into FeLV-C in one cat mirrored those of natural infection. Two cats developed persistent antigenemia; six cats were transiently antigenemic. Reactivation of infection occurred in some cats. One recipient developed non-regenerative anemia associated with FeLV-C, and four others developed a T-cell lymphoma, one with secondary lymphoblastic leukemia. Five of the ten recipient cats received provirus-positive aviremic blood, whereas the other five received provirus- and viral RNA-positive but aviremic blood. Notably, the cats that received blood containing only proviral DNA exhibited a later onset but graver outcome of FeLV infection than the cats that were transfused with blood containing proviral DNA and viral RNA. Leukocyte counts and cytokine analyses indicated that the immune system of the latter cats reacted quicker and more efficiently.

Conclusions

Our results underline the biological and epidemiological relevance of FeLV provirus carriers and the risk of inadvertent FeLV transmission via blood transfusion and demonstrate the replication capacity of proviral DNA if uncontrolled by the immune system. Our results have implications not only for veterinary medicine, such as the requirement for testing blood donors and blood products for FeLV provirus by sensitive polymerase chain reaction, but are also of general interest by revealing the importance of latent retroviral DNA in infected hosts. When aiming to eliminate a retroviral infection from a population, provirus carriers must be considered.

Electronic supplementary material

The online version of this article (doi:10.1186/s12977-015-0231-z) contains supplementary material, which is available to authorized users.

Blood transfusion in cats: ABCD guidelines for minimising risks of infectious iatrogenic complications

OVERVIEW

The availability of blood components has increased the number of indications for transfusing cats, and fresh whole blood is readily accessible to clinicians because it can be taken from in-house donor cats or 'volunteer' feline blood donors. A certain amount of risk remains to the recipient cat, as immediate or delayed adverse reactions can occur during or after transfusion, related to immunemediated mechanisms. This article, however, focuses on adverse events caused by infectious agents, which may originate either from contamination of blood following incorrect collection, storage or transfusion, or from transfusion of contaminated blood obtained from an infected donor.

PREVENTION OF BLOOD CONTAMINATION

In cats, blood cannot be collected through a closed system and, therefore, collection of donor blood requires a multi-step manipulation of syringes and other devices. It is crucial that each step of the procedure is performed under the strictest aseptic conditions and that bacterial contamination of blood bags is prevented, as bacterial endotoxins can cause an immediate febrile reaction or even fatal shock in the recipient cat.

PREVENTION OF DISEASE TRANSMISSION

With a view to preventing transmission of blood-borne infectious diseases, the American College of Veterinary Internal Medicine has adopted basic criteria for selecting pathogens to be tested for in donor pets. The worldwide core screening panel for donor cats includes feline leukaemia virus, feline immunodeficiency virus, Bartonella species and feline haemoplasma. The list should be adapted to the local epidemiological situation concerning other vector-borne feline infections. The most practical, rapid and inexpensive measure to reduce transfusion risk is to check the risk profile of donor cats on the basis of a written questionnaire. Blood transfusion can never, however, be considered entirely safe.

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.

The flat cat: 2. the emergency database and management of common metabolic abnormalities

AIM

Detailed information regarding the causes and treatment of acute collapse in the cat can be difficult to locate in a single published source. This two-part review aims to provide a logical approach to the clinical assessment and stabilisation of the critically ill collapsed cat.

PRACTICAL RELEVANCE

Laboratory evaluation, in the form of an emergency database, is an important part of the initial assessment of a collapsed patient and should be considered in conjunction with physical abnormalities.

CLINICAL CHALLENGES

Rapid identification and correction of life-threatening metabolic abnormalities, including hypoglycaemia, hypocalcaemia and hyperkalaemia, is essential in stabilising this group of patients. Clinicians often lack confidence if they are not dealing with these problems regularly.

AUDIENCE

The information provided in this article will be of use to any veterinarian working with feline patients and particularly those dealing with emergencies on a regular basis.

EVIDENCE BASE

There is an extensive body of published literature, both original studies and textbook chapters, pertaining to the causes and treatment of the important metabolic abnormalities covered in this article. The authors draw on information from original articles, reviews and their clinical experience to provide simple but detailed practical information to guide interpretation of the emergency database and its application to therapy in the emergency setting.

Xenotransfusion with canine blood in the feline species: review of the literature

Xenotransfusion (the transfusion of blood from another species) of canine blood to cats has been historically performed commonly and is still performed nowadays in some countries. Considering the current lack of commercial availability of haemoglobin-based oxygen carrier solution (Oxyglobin), there may be rare occasions when treating an anaemic cat when compatible feline blood cannot be obtained, and where a transfusion with canine blood may need to be considered as a life-saving procedure. This article reviews the published evidence about feline xenotransfusion with canine blood and the results that can be expected with this procedure. Published evidence in a limited number of cases (62 cats) indicates that cats do not appear to have naturally-occurring antibodies against canine red blood cell antigens: compatibility tests prior to the first transfusion did not demonstrate any evidence of agglutination or haemolysis of canine red cells in feline serum or plasma. No severe acute adverse reactions have been reported in cats receiving a single transfusion with canine whole blood. Anaemic cats receiving canine blood are reported to improve clinically within hours. However, antibodies against canine red blood cells are produced rapidly and can be detected within 4-7 days of the transfusion, leading to the destruction of the transfused canine red cells in a delayed haemolytic reaction. The average lifespan of the transfused canine red cells is less than 4 days. Any repeated transfusion with canine blood later than 4-6 days after the first transfusion causes anaphylaxis, which is frequently fatal.