Clinical Use of Blood Products in Cats: A Retrospective Study (1997-2000)

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

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.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

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.

Feline comorbidities: What do we really know about feline triaditis?

PRACTICAL RELEVANCE

Feline triaditis describes concurrent pancreatitis, cholangitis and inflammatory bowel disease (IBD). The reported prevalence is 17-39% in ill referral patients. While the aetiology is poorly understood, it is known to include infectious, autoimmune and physical components. What is not known is whether different organs are affected by different diseases, or the same process; indeed, triaditis may be part of a multiorgan inflammatory disease. Feline gastrointestinal tract anatomy plays its role too. Specifically, the short small intestine, high bacterial load and anatomic feature whereby the pancreatic duct joins the common bile duct before entering the duodenal papilla all increase the risk of bacterial reflux and parenchymal inflammation. Inflammation may also be a sequela of bowel bacterial translocation and systemic bacteraemia.

DIAGNOSTIC CHALLENGES

Cholangitis, pancreatitis and IBD manifest with overlapping, vague and non-specific clinical signs. Cholangitis may be accompanied by increased serum liver enzymes, total bilirubin and bile acid concentrations, and variable ultrasonographic changes. A presumptive diagnosis of pancreatitis is based on increased serum pancreatic lipase immunoreactivity or feline pancreas-specific lipase, and/or abnormal pancreatic changes on ultrasonography, though these tests have low sensitivity. Diagnosis of IBD is challenging without histopathology; ultrasound findings vary from normal to mucosal thickening or loss of layering. Triaditis may cause decreased serum folate or cobalamin (B12) concentrations due to intestinal disease and/or pancreatitis. Triaditis can only be confirmed with histopathology; hence, it remains a presumptive diagnosis in most cases.

EVIDENCE BASE

The literature on feline triaditis, pancreatitis, cholangitis and IBD is reviewed, focusing on histopathology, clinical significance and diagnostic challenges. Current management recommendations are provided. Further studies are needed to understand the complex pathophysiology, and in turn improve diagnosis and treatment.

Retrospective evaluation of the indications, safety and effects of fresh frozen plasma transfusions in 36 cats (2014-2018)

OBJECTIVES

The goals of this study were to classify the indications, risks, effects on coagulation times and outcomes of cats receiving fresh frozen plasma (FFP) transfusions in clinical practice.

METHODS

This was a retrospective study of FFP transfusions administered in two referral hospitals from 2014 to 2018. Transfusion administration forms and medical records were reviewed. Information was collected on indication, underlying condition, coagulation times and signs of transfusion reactions. Seven-day outcomes after FFP administration were also evaluated when available.

RESULTS

Thirty-six cats received 54 FFP transfusions. Ninety-four percent of cats were administered FFP for treatment of a coagulopathy. Twenty cats had paired coagulation testing before and after FFP administration. Eighteen of these cats had improved coagulation times after receiving 1-3 units of FFP. Eight of the 36 cats had probable transfusion reactions (14.8% of 54 FFP transfusions). These reactions included respiratory signs (n = 4), fever (n = 2) and gastrointestinal signs (n = 2). Five of the eight cats with probable reactions had received packed red blood cells contemporaneously. Overall mortality rate during hospitalization was 29.7%, with 52.8% (n = 19/36) of cats confirmed to be alive 7 days after discharge.

CONCLUSIONS AND RELEVANCE

This retrospective study shows that FFP transfusions improve coagulation times in cats. Transfusion reactions are a risk, and risk-benefit ratios must be measured prior to administration and possible reactions monitored. In the study cats, the FFP transfusions appeared to be a tolerable risk given the benefit to prolonged coagulation times.

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.

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

OBJECTIVES

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

MATERIAL AND METHODS

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

RESULTS

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

CLINICAL IMPORTANCE

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

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS AND RELEVANCE

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

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.

Haematological and morphological evaluation of feline whole blood units collected for transfusion purposes

OBJECTIVES

Despite the increasing availability of feline blood collected and stored for transfusion purposes, few studies have been performed on feline blood units. The aim of this prospective in vitro study was to evaluate haematological and morphological changes in feline blood cells in whole blood units between collection and end of storage.

METHODS

Haematological examination (red blood cells [RBCs], haemoglobin, haematocrit, red cell distribution width, mean cell volume, mean cell haemoglobin concentration, mean cell haemoglobin, white blood cells [WBCs] and platelet [PLT] count) was performed on 40 non-leukoreduced feline whole blood units at the time of collection (day[D]0) and after storage (D35). The blood was collected into citrate-phosphate-dextrose-adenine anticoagulant-preservative solution using an open system in a veterinary blood bank and stored for 35 days at 4 ± 2°C. Twenty of these feline whole blood units were also analysed for blood cell morphology (normal RBCs, macrocytes, echinocytes, spherocytes, schistocytes, lysed RBCs, RBCs with Heinz bodies and recognisable WBC and PLT count). Differences between the two examination times were statistically analysed.

RESULTS

There was a statistically significant decrease in WBC and PLT counts after storage at D35 (P <0.0001 for both). The most significant cellular morphological changes after storage were an increase in echinocyte count (P = 0.0001), and lysed RBCs (P <0.0001), and a decrease in normal RBCs (P <0.0001). Recognisable WBCs - mainly lymphocytes - were present at the end of storage.

CONCLUSIONS AND RELEVANCE

This study showed that significant morphological changes occur in RBCs in feline blood units during storage for 35 days. In vivo studies are required to establish if these changes could affect the ability of stored RBCs to circulate and provide adequate oxygen delivery 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.

Assessment of five formulae to predict post-transfusion packed cell volume in cats

This retrospective study aimed to identify the most accurate formula for estimating the increase in packed cell volume (PCV) after whole blood transfusion of cats, as several formulae have been reported but not validated. Forty cats, of varying breeds and gender, were included from two referral institutions after database searches over a 13 year period. Five formulae were used to calculate an estimated post-transfusion PCV based on the re-working of formulae for determining the volume of donor blood to be transfused; three formulae were derived from those previously reported in the feline literature and two from human paediatric medicine, where a similar mean blood volume has been described. Cats were subdivided into two groups, the first consisting of 17 cats with non-regenerative anaemia and the second consisting of 23 cats with ongoing losses such as haemolysis and haemorrhage; it was hypothesised that formulae could be more accurate for group 1 cats, whereas formulae applied to group 2 cats could have overestimated the post-transfusion PCV. Bland-Altman analysis was performed for all cats to compare the actual increase in PCV with the calculated increase for the five formulae. Formula 1 (PCV % increase = volume of blood transfused in ml/2 × bodyweight in kg) performed best overall and is easy to calculate; however, no single formula was highly accurate at predicting the PCV increase after whole blood transfusion in cats and, owing to the wide confidence intervals, these formulae should be applied judiciously in the clinical setting.

A retrospective study of 180 anaemic cats: features, aetiologies and survival data

The study comprised 180 anaemic cats. Descriptive and survival data were obtained. Cats were classified by aetiology of anaemia development and degenerative, anomalous, metabolic, miscellaneous, neoplastic, infectious, inflammatory, immune-mediated, toxic, traumatic or vascular disease (DAMNITV) classification and anaemia severity. Sixty-four (35.6%) cats had mild [packed cell volume (PCV)/haematocrit (HCT) 20-24.9%], 58 (32.2%) moderate (14-19.9%), 23 (12.8%) severe (11-13.9%) and 35 (19.4%) very severe (<10.9%) anaemia. By aetiology of anaemia development, bone marrow (BM) abnormalities were more common (95, 52.8%) than haemorrhage (37, 20.6%) or haemolysis (19, 10.6%). By DAMNITV classification, infectious diseases were more common (39, 21.7%) than neoplasia (36, 20%), metabolic (21, 11.7%), trauma (15, 8.3%), miscellaneous (14, 7.8%), inflammatory (11, 6.1%), immune-mediated (11, 6.1%), anomalous (8, 4.4%), toxic (2, 1.1%) or vascular disease (1, 0.6%). BM abnormalities were significantly associated with more severe anaemia (P = 0.003). Most cats (112, 62.2%) survived to discharge whereas 55 (30.6%) were euthanased and 13 (7.2%) died. Survival to discharge was not associated with anaemia severity but was associated significantly with aetiology of anaemia development (P = 0.046), as cats with haemolysis were more likely to survive to discharge than cats with BM abnormalities. Survival to discharge was also associated significantly with DAMNITV classification (P = 0.010), with cats with neoplasia being less likely, and cats with immune-mediated disease more likely, to survive to discharge. Cox regression analysis found that survival was not associated with anaemia severity, but was associated with DAMNITV classification (P = 0.011) and age (P = 0.082), with cats with immune-mediated disease and younger cats more likely to survive.

Feline blood transfusions: A pinker shade of pale

PRACTICAL RELEVANCE

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

PATIENT GROUP

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

CLINICAL CHALLENGES

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

DIAGNOSTICS

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

EVIDENCE BASE

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