Received: 12 August 2022 Revised: 10 January 2023 Accepted: 21 January 2023 DOI: 10.1111/vec.13376 OR I G I N A L S T UDY Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitationmodel using lactated Ringer’s solution or 6% tetrastarch 130/0.4 Gareth E. Zeiler BVSc(Hons), MMedVet(Anaesth), PhD, DECVECC, DECVAA, DACVAA1,2,3 Brighton T. Dzikiti BVSc,MSc, PhD1,4 Eva Rioja BVSc, DVM, PhD, DACVAA5 Peter Kamerman BSc, PhD3 Roxanne K. Buck BVSc,MMedVet(Anaesth), DECVAA1 Friederike Pohlin BVSc, PhD1 Andrea Fuller BSc, PhD3 1Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa 2Anaesthesia and Critical Care Services, Valley FarmAnimal Hospital, Pretoria, South Africa 3Brain Function Research Group, School of Physiology, University of theWitwatersrand, Johannesburg, South Africa 4Clinical Sciences Department, Ross University School of VeterinaryMedicine, Basseterre, Saint Kitts andNevis 5Optivet Referrals, Havant, UK Correspondence Gareth E. Zeiler, Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa. Email: gareth.zeiler@up.ac.za Data have been presented in the form of a chapter and published in an online PhD thesis by the University ofWitwatersrand (https://hdl.handle.net/10539/29950). Funding information South African Veterinary Foundation; Health andWelfare Sector Education and Training Authority (HWSETA); University of Pretoria Research Development Program; South African National Research Foundation Abstract Objective: To describe and compare prothrombin time (PT), activated partial throm- boplastin time (aPTT), thromboelastography (TEG), HCT, and platelet count measure- ments in a hemorrhage/over-resuscitationmodel. Design:Randomized crossover study. Setting:University teaching hospital. Animals: Six cats. Interventions: Anesthetized cats underwent 3 treatments at 2-month intervals. The treatments were as follows: NHR—no controlled hemorrhage and sham resuscitation; LRS—controlled hemorrhage and lactated Ringer’s solution (LRS) for resuscitation; and Voluven—controlled hemorrhage and 6% tetrastarch 130/0.4 for resuscitation. The LRS and Voluven were administered at 60 and 20 mL/kg/h, respectively, for 120 minutes. Blood samples were drawn for PT, aPTT, TEG, HCT, and platelet count measurements at a healthy check (T − 7d), after controlled hemorrhage (T0), at 60 and 120 minutes of resuscitation (T60 and T120), and at 24 hours after completion of resuscitation (T24h). Data were analyzed using a general linear mixedmodel approach (significance was P< 0.05). Measurements andMainResults:Totalmedian blood loss (controlled hemorrhage and blood sampling from T0 to T120) at T120 was 11.4, 31.0, and 30.8 mL/kg for NHR, LRS, and Voluven, respectively. PT and aPTT during LRS and Voluven were prolonged at T60 andT120 compared toNHR (P<0.001).OnTEG, the reaction time, kinetic time, Abbreviations: aPTT, activated partial thromboplastin time; PT, prothrombin time; TEG, thromboelastography. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and nomodifications or adaptations aremade. © 2024 The Author(s). Journal of Veterinary Emergency and Critical Care published byWiley Periodicals LLC on behalf of Veterinary Emergency and Critical Care Society. 356 wileyonlinelibrary.com/journal/vec J Vet Emerg Crit Care. 2024;34:356–367. https://orcid.org/0000-0001-7653-7726 mailto:gareth.zeiler@up.ac.za https://hdl.handle.net/10539/29950 http://creativecommons.org/licenses/by-nc-nd/4.0/ https://wileyonlinelibrary.com/journal/vec http://crossmark.crossref.org/dialog/?doi=10.1111%2Fvec.13376&domain=pdf&date_stamp=2024-06-14 ZEILER ET AL. 357 and alpha-angle were within reference intervals for cats at all time points in all treat- ments, while maximum amplitude was less than the reference interval (40 mm) at T0, T60, andT120duringVoluvenandatT60andT120during LRS compared toNHR (both P<0.001). TheHCTandplatelet countwere significantly lower at T60andT120during LRS and Voluven compared to NHR (P< 0.001). Conclusions: Hypocoagulopathy was observed during hemorrhage and liberal fluid resuscitation. Prolongation of PT and aPPT and decreased clot strengthmay have been caused by hemodilution and platelet loss. KEYWORDS activated partial thromboplastin time, feline, prothrombin time, resuscitation, thromboelastography 1 INTRODUCTION Cats are often anaesthetized for surgical procedures, and the risk of intraoperative hemorrhage is always present.1 Intraoperative hemor- rhage, if severe enough, might cause hypovolemia and hypotension that may warrant resuscitation using isotonic crystalloid or colloid fluids. Hemodilution in vitro studies on dog blood, where blood has been diluted to standardized HCTs or using various blood:fluid dilu- tion ratios, resulted in coagulopathies.2,3 Furthermore, reviews of in vivo fluid therapy, in dogs, also highlight clinical coagulopathies as a concern during resuscitation, especially when synthetic colloids, like hydroxyethyl starch, are administered.4,5 However, the effect of hemorrhage or fluid administration on coagulation in cats is scant- ily reported5; instead, theories are extrapolated from dogs, for which the effects are presumed to be similar. More recently, an in vitro study in which Ringer’s acetate and tetrastarch 6% 130/0.42 were mixed with feline fresh whole blood at a ratio of 1:6 and effects on global coagulation were measured using rotational thromboelastome- try (ROTEM) reported evidence of hypocoagulability. The tetrastarch 6% 130/0.42 caused a greater hypocoagulable effect compared to the Ringer’s acetate fluid. However, themagnitude of the effects fromboth fluids was mostly within normal reference intervals of the laboratory and therefore the authors expressed reservations about the clinical relevance of these observations.6 Screening test methods of hemostasis include determining the pro- thrombin time (PT) and activated partial thromboplastin time (aPTT).7 These methods test the functioning of secondary hemostasis only and therefore viscoelastic coagulation testing methods, which assess global coagulation function, have been introduced.8 Thromboelastog- raphy (TEG) is a viscoelastic coagulation testing method in which a tracing is plotted during coagulation, and various variables are deter- mined during the precoagulation, coagulation, and fibrinolysis phases of hemostasis. The screening tests of hemostasis have been used routinely for decades and therefore the preanalytical and analytical methods are established and adhered to in practice.7 However, TEG is sensitive to many preanalytical and analytical methodological dif- ferences and therefore incorrect clinical conclusions could be drawn from the outcomes of this test. Therefore, a standardize testing and reporting protocols should be followed, as set out by PROVETS.9–14 Hypocoagulability and hypercoagulability have not yet been clearly defined in cats because there is insufficient evidence to allow formu- lation of such definitions.9 The screening assays only detect coagu- lopathies when there are profound derangements.7 These screening tests cannot be used to define a hypercoagulable state but may pro- vide information about hypocoagulability.8,15 The TEG, which assesses global coagulation function, has trace variables that can indicate hypocoagulability, including prolongation in R-times and K-times, and decreases in α-angle, maximum amplitude (MA), and G-values compared to laboratory reference intervals (and vice versa for a hypercoagulable state).9 Guided by the PROVETS guidelines, the aims of the present study were to investigate the effects of hemorrhage followed immediately by resuscitation with an isotonic crystalloid or hydroxyethyl tetrastarch 6% 130/0.4 on PT, aPTT, TEG, HCT, and platelet count in anaes- thetized cats.Wehypothesized that therewouldbenodifference in the hemostatic profiles of the cats among the treatments. 2 MATERIAL AND METHODS 2.1 Animals A group of 6 sterilized cats (3 males and 3 females; mean ± standard deviation of 21 ± 1 months and 4.9 ± 1.2 kg) were used for the study. The sample size was based on availability and the study budget. They were part of a colony that was housed in a communal indoor–outdoor cattery. The cats were cared for by experienced research officers man- aging the cattery and fed a commercial cat dieta and offered water ad libitum. The animal ethics committees of the University of Preto- ria (v006-15) and University of Witwatersrand (2017-10-68-C-AREC) approved the study. This study was part of a larger fluid resuscitation project where an assessment tool to predict the volume of blood being lost and to identify biomarkers for impending volume overloadwas pri- marily investigated for a PhD degree.1,16,17 Resuscitation fluids were 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense 358 ZEILER ET AL. administered in excess in order to identify biomarkers for impend- ing volume overload. We only report on data relevant to the present study. Four months before starting the project data collection, when the cats underwent neutering, the right common carotid artery was superficialized by suturing the sternohyoid and sternocleidomastoid muscles together underneath the isolated and exposed 1-cm section of the artery. The cats underwent a health check assessment 1 week prior to the treatments through a clinical examination and hemostatic and hematology profiling. No cats were excluded from participating in the study following the pretreatment evaluation. Food, but not water, was withheld 8 hours prior to treatment. 2.2 Study procedures Cats were randomly allocated (balanced single block design using a websiteb) to receive 3 treatments at 2-month intervals. On the morning of treatment, the cat was transferred to the theatre com- plex of the hospital where it underwent a brief clinical examination and was weighed. The cat was premedicated with buprenorphine hydrochloridec (0.02 mg/kg) intramuscularly and left undisturbed for 45 minutes. The cat was then transferred to the anesthetic induc- tion room, and an indwelling catheterd was aseptically inserted into one of the cephalic veins and secured. Alfaxalonee was administered intravenously by titration to effect to induce general anesthesia. The trachea was intubated with a cuffed endotracheal tubef, which was secured in place by a gauze roll tied behind the ears, and connected to a pediatric circle breathing systemg. General anesthesia in the spon- taneously breathing cats was maintained by delivering isofluraneh in oxygen at a fixed flow rate of 80 mL/kg/min with the vaporizeri initially set at 2%. A target end-tidal isoflurane concentration of 1.7% was used as the standard for maintaining general anesthesia throughout the procedures. The ventral neck region was clipped and surgically scrubbedj before the cat was transferred to the surgery theatre. Once in theatre, the cat was placed in dorsal recumbency and con- nected to the anesthetic delivery device, as previously described. A crystalloidk was infused by an electronic devicel at 5 mL/kg/h via a y- ported administration setm connected to the cephalic catheter for peri- anesthetic maintenance fluids (maintenance fluids). Probes and leads were placed and connected to a multiparameter machinen to monitor various physiological variables as follows: heart rate by electrocardio- gram (ECG), peripheral oxyhemoglobin saturation by pulse oximetry, end-tidal isoflurane concentration and end-tidal carbon dioxide by spectrophotometry gas analysis, respiratory rate by capnography, and esophageal temperature by thermistor probe. Body temperature was maintained within a range of 36.0–38.0◦C throughout the procedure by wrapping the cat’s body in a blanket. A cathetero was inserted into the previously superficialized right carotid artery following skin cut- down to allow for invasive blood pressure monitoring. A catheter◦ was inserted percutaneously into the left jugular vein for intermittent blood sampling and facilitation of controlled hemorrhage later. Both catheters were inserted by the Seldinger technique.18 Then, 1 of the 3 randomly allocated treatments was commenced. The treatments were divided into 2 phases, the hemorrhage phase and resuscitation phase, as follows: Treatment NHR: The cat underwent a sham-controlled hemor- rhage phase of 15 minutes duration and a sham resuscitation phase of 120minutes duration. Treatment LRS: The cat underwent a controlled hemorrhage phase until an endpoint was reached (see below), followed by a resuscitation phasewhereby lactated Ringer’s solutionk was infused at 60mL/kg/h for 120minutes. Treatment Voluven: The cat underwent a controlled hemorrhage phase until an endpoint was reached (see below), followed by a resuscitation phase whereby 6% tetrastarch 130/0.4p was infused at 20mL/kg/h for 120minutes. During the hemorrhage phase, blood was drawn manually into a semiclosed system using 20-mL syringesq primedwith 4mL of citrate– phosphate–dextroser via the jugular catheter at a targeted rate of 2 mL/kg/min until 1 of 2 endpoints. The endpoint was either a (1) max- imum blood drawl of 30 mL/kg or (2) mean arterial blood pressure of <48 mm Hg that persisted for at least 3 minutes, whichever hap- pened first.1 Blood obtained during the hemorrhage phase was stored for 24 hours in the event that the cat required a transfusion during the recovery phase to treat hemorrhagic shock. During the resuscitation phase, which started within minutes after the hemorrhage phase, the randomized resuscitation fluid was infused via a second electronic devicel, where its administration setm was con- nected to the y-port of the maintenance fluid administration set. Both fluids were administered simultaneously in LRS and Voluven, and NHR only receivedmaintenance fluids. Blood samples were obtained and physiological variables were recorded at fixed time points during the hemorrhage and resuscita- tion phases. On completion of the resuscitation phase, all monitoring equipment and catheters, except the jugular catheter, were removed. The carotid artery catheter was removed, and digital pressure was applied until a stable clot was formed. If a stable clot did not form within 15 minutes, then a hemostatic absorbable meshs was applied using digital pressure for 10minutes, or until hemostasis was achieved. The cutdown incision site was then sutured using a 2-layer closure technique with absorbable suture materialt. The cat received a sin- gle subcutaneous injection of meloxicamu (0.2 mg/kg) and intravenous injection of buprenorphine† (0.03mg/kg). The catwas then transferred to the ICU of the hospital for recovery from general anesthesia and overnight observationwithout any further treatments or interventions performed. Then, 24 hours later, blood was sampled and the jugular catheter was removed following which the cat was transferred back to the cattery. All cats were rehomed, without evidence of renal or other organ injury or dysfunction, through an adoption process 1month after conclusion of the data collection phase of the project. 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense ZEILER ET AL. 359 2.3 Data collection Data relevant to the present studywere collected in the formof coagu- lation andhematology profiling during the health check (T−7d), during the treatment period (immediately after hemorrhage phase [T0] and at 60 and 120 min [T60 and T120, respectively]), and 24 hours later (T24h). The total blood loss at each time point was cumulative and included the controlled hemorrhage volume (not applicable in NHR) and all blood samples for profiling. Only the total volumes of fluids that were administered during resuscitation were used for report- ing because all cats were administered maintenance fluids during all treatments. Blood samples relevant to this study were drawn from the jugular vein by direct puncture using a needle and syringe and decanted into 2 different storage tubesv,w at T − 7d, or via the jugular catheter into a syringe and immediately decanted into the storage tubes during the treatment period (T0, T60, and T120) and at T24h. Before collection of a blood sample from the catheter, a waste blood sample (1.5 mL) was always discarded. The sodium citrate tubev was filled to 2.7 mL, as recommended by the manufacturer to ensure a final sodium citrate concentration 3.2% (109 mmol/L). The stored blood was submitted to the onsite laboratory immediately for handling and measurement of TEGx, PTy, aPTTy, and hematologyz (hemoglobin concentration, HCT, RBC, and platelet counts) using daily-calibrated machines, operated by experienced veterinary clinical technologists. The RBC and platelet counts were verified on blood smears. The TEG assay followed a standardized protocol. First, the citrated whole blood was rested for 30 minutes. The cup was prepared by adding 0.02mL of CaCl2 aa buffer. Then, 0.4 mL of citrated whole blood was mixed with 0.025 mL of tissue factorab (tissue factor concentra- tion 1:500,040). Then, 0.34mLof the citratedwhole bloodmixturewas added to the cup, and the assay was started and ran for 90 minutes at 37◦C.The remaining citratedwhole bloodnot used in theTEGwas then spun down (2500 × g for 15 min at room temperature) to separate the cellular components from the plasma. The plasmawas then placed into the calibratedmachiney tomeasure the PT and aPTT assays using stan- dard manufacture assay methodology. Thromboplastin regentac based on recombinant human tissue factor was used for the for the PT assay, and synthetic phospholipid reagentad was used for the aPPT assay. The clinical pathology laboratory used their healthy cat reference intervals for the control values for the TEG, PT, and aPPT assays for interpre- tation. Our clinical pathology laboratory adhered to current practice recommendations, and its reference range intervals are similar to those of other cat studies.19–21 2.4 Data analysis The data were tested for normality by plotting histograms, evaluat- ing descriptive statistics, kurtosis, skewness, and standard error, and performing the Anderson–Darling test for normality. Some of the PT and aPTT results exceeded the upper limit of detection for the assay and therefore these data were rank-transformed prior to further anal- ysis. All variables were compared among treatments and over time, as well as the interaction of time × treatment using a general linear mixed model (fixed factors: time and treatment; random factors: cats) following which variables showing significant differences underwent post hoc comparisons using Bonferroni correction for repeated mea- sures. Model fits were assessed by visually inspecting residual plots to assess linearity, homogeneity of variances, normality, and outliers. Fisher’s exact test was used to determine if there was a difference in requiring the hemostaticmesh after arterial catheter removal between NHR treatment to LRS and Voluven, respectively. To aid in interpreting the coagulation assays, selected measured and calculated cardiopul- monary variables were tabulated. Data were nonnormally distributed and therefore reported as median (Q1–Q3) for nonanalyzed variables (blood loss volumes, endpoints reached, volumes of fluid administered, etc), and data analyzed using the general linear mixed model were reported as estimated marginal means with 95% confidence intervals from the models. Data were analyzed using a commercially available softwareae, and statistical significance was set at P< 0.05. 3 RESULTS The maximum blood draw volume endpoint was applied 4 times (LRS: n = 2; Voluven: n = 2), while the mean arterial pressure (MAP) end- point was applied 8 times (LRS: n = 4; Voluven: n = 4). None of the cats required an autologous blood transfusion to treat hemorrhagic shock at any time during the study. The amount of blood lost at T60 was 7.6 (4.9–7.8), 27.3 (17.1–33.5), and 27.0 (19.2–30.4) mL/kg for NHR, LRS, and Voluven, respectively. The total volume of fluids administered for resuscitation at T60 was 0, 60, and 20 mL/kg for NHR, LRS, and Volu- ven, respectively. The ratio of fluid administration to blood loss at T60 was approximately 2.2:1 and 0.7:1 for LRS and Voluven, respectively. The total blood lost at T120 was 11.4 (7.4–11.7), 31 (19.4–37.6), and 30.8 (21.6–34.8) mL/kg for NHR, LRS, and Voluven, respectively. The total volume of fluids administered for resuscitation at T120 was 0, 120, and 40 mL/kg for NHR, LRS, and Voluven, respectively. The ratio of fluid administration to blood loss at T120 was approximately 3.9:1 and 1.3:1 for LRS and Voluven, respectively. On removal of the carotid artery catheter, a hemostatic absorbable mesh was required in LRS (n = 5; P = 0.01515) and Voluven (n = 3; P = 0.1818) but not NHR. Selected cardiopulmonary variables are presented in Table 1. Results on hematological variables are summarized in Table S1. The RBC count was significantly reduced during LRS and Voluven at T60 andT120compared toother timepoints andalso significantly different from the NHR (treatment × time: P < 0.001). Hemoglobin concen- tration and HCT changed in a similar way to the RBC count (both: treatment× time:P<0.001). The platelet countwas significantly lower during LRS and Voluven at T60 and T120 compared to other time points and different from NHR (treatment × time: P < 0.001). The sig- nificantly different values for the hematological variables were lower than the laboratory reference interval for cats (Figure 1). The PT and aPTT results are summarized in Table S2 and Figure 2. The control reference intervals for PT and aPTT measured by the 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense 360 ZEILER ET AL. T A B L E 1 Se le ct ed m ea su re d an d ca lc u la te d ca rd io p u lm o n ar y an d b io ch em is tr y va ri ab le s o f6 an ae st h et iz ed ca ts (b u p re n o rp h in e, al fa xa lo n e, an d is o fl u ra n e in ox yg en )u n d er go in g co n tr o lle d h em o rr h ag e an d fl u id re su sc it at io n u si n g la ct at ed R in ge r’ s so lu ti o n (L R S) o r 6 % te tr as ta rc h 1 3 0 /0 .4 (V o lu ve n )o r n o co n tr o lle d h em o rr h ag e n o r re su sc it at io n (N H R )t re at m en t. V ar ia b le U n it T im e T − 1 5 T 0 T 6 0 T 1 2 0 M ed ia n (Q 1 – Q 3 ) M ed ia n (Q 1 – Q 3 ) M ed ia n (Q 1 – Q 3 ) M ed ia n (Q 1 – Q 3 ) Tr ea tm en t N H R H ea rt ra te p er m in 1 0 7 (9 8 – 1 2 8 ) 1 0 4 (9 7 – 1 2 8 ) 1 4 4 (1 0 9 – 1 7 2 ) 1 4 5 (1 1 3 – 1 9 6 ) R es p ir at o ry ra te p er m in 1 6 (9 – 1 7 ) 1 5 (9 – 1 9 ) 2 8 (1 8 – 3 2 ) 3 1 (1 9 – 4 0 ) SA P m m H g 8 9 (8 1 – 9 3 ) 8 6 (8 1 – 9 4 ) 1 0 3 (8 4 – 1 2 5 ) 9 5 (8 3 – 9 8 ) M A P m m H g 6 8 (6 1 – 7 8 ) 6 4 (6 1 – 6 8 ) 8 5 (6 5 – 1 0 2 ) 7 2 (6 3 – 8 3 ) D A P m m H g 5 4 (4 7 – 6 5 ) 5 2 (4 7 – 5 6 ) 6 8 (5 1 – 8 2 ) 5 8 (4 9 – 6 5 ) La ct at e m m o l/ L 1 .4 (1 .2 – 1 .8 ) 1 .5 (1 .2 – 1 .8 ) 1 .5 (1 .3 – 2 .2 ) 1 .9 (1 .7 – 2 .2 ) B E m m o l/ L − 7 .8 (− 9 .0 to − 6 .5 ) − 8 .1 (− 8 .9 to − 6 .5 ) − 8 .0 (− 1 0 .4 to − 6 .5 ) − 6 .9 (− 9 .3 to − 4 .8 ) P v O 2 m m H g 9 9 (6 4 – 1 1 3 ) 9 3 (7 3 – 1 0 5 ) 7 9 (7 0 – 1 2 8 ) 7 4 (6 0 – 9 3 ) C v O 2 m L/ d L 1 1 .1 (1 0 .6 – 1 2 .0 ) 1 0 .9 (1 0 .6 – 1 1 .6 ) 1 1 .8 (1 0 .5 – 1 3 .8 ) 1 1 .3 (1 0 .5 – 1 2 .0 ) O E R % 9 .6 (8 .3 – 1 4 .9 ) 9 .6 (8 .8 – 1 2 .8 ) 1 1 .0 (7 .2 – 1 4 .0 ) 1 3 .5 (9 .4 – 1 9 .3 ) P C O 2 (v – a) m m H g 5 0 (3 9 – 7 7 ) 5 5 (4 6 – 5 8 ) 4 7 (4 2 – 8 6 ) 4 1 (2 2 – 6 8 ) P C O 2 (v – a) /C O 2 (a – v) m m H g⋅ d L/ m L 3 9 .6 (2 0 .8 – 7 2 .8 ) 4 4 .4 (3 2 .9 – 5 0 .8 ) 2 9 .1 (2 5 .9 – 9 3 .1 ) 2 1 .9 (1 0 .0 – 5 9 .3 ) Tr ea tm en t LR S H ea rt ra te p er m in 1 0 6 (1 0 2 – 1 1 9 ) 1 6 5 (1 5 1 – 1 9 3 ) 1 2 5 (1 0 9 – 1 5 3 ) 1 7 9 (1 4 7 – 2 0 6 ) R es p ir at o ry ra te p er m in 1 6 (9 – 1 7 ) 2 1 (1 3 – 2 5 ) 1 7 (9 – 2 2 ) 2 6 (1 8 – 3 8 ) SA P m m H g 9 0 (8 5 – 9 3 ) 6 1 (5 8 – 7 1 ) 9 2 (8 7 – 1 0 8 ) 9 5 (9 1 – 1 3 8 ) M A P m m H g 7 3 (6 3 – 7 7 ) 4 5 (4 1 – 4 9 ) 7 1 (6 4 – 8 9 ) 8 0 (6 9 – 1 0 9 ) D A P m m H g 5 7 (4 9 – 6 2 ) 3 6 (3 4 – 4 2 ) 5 5 (4 8 – 7 0 ) 6 6 (5 3 – 8 4 ) (C o n ti n u es ) 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense ZEILER ET AL. 361 T A B L E 1 (C o n ti n u ed ) V ar ia b le U n it T im e T − 1 5 T 0 T 6 0 T 1 2 0 M ed ia n (Q 1 – Q 3 ) M ed ia n (Q 1 – Q 3 ) M ed ia n (Q 1 – Q 3 ) M ed ia n (Q 1 – Q 3 ) La ct at e m m o l/ L 1 .9 (1 .6 – 2 .6 ) 1 .8 (1 .4 – 2 .3 ) 2 .9 (2 .2 – 4 .4 ) 3 .5 (2 .8 – 3 .8 ) B E m m o l/ L − 8 .7 (− 9 .5 to − 5 .9 ) − 9 .2 (− 1 0 .6 to − 6 .6 ) − 4 .9 (− 6 .5 to − 4 .0 ) − 3 .4 (− 4 .7 to − 3 .2 ) P vO 2 m m H g 6 8 (5 2 – 1 0 4 ) 4 7 (4 1 – 5 7 ) 1 0 1 (7 6 – 1 4 6 ) 8 3 (5 1 – 1 4 3 ) C vO 2 m L/ d L 1 0 .9 (9 .3 – 1 2 .1 ) 1 0 .5 (9 .4 – 1 1 .1 ) 6 .4 (5 .0 – 6 .8 ) 5 .2 (4 .4 – 8 .1 ) O E R % 1 4 .7 (8 .2 – 2 4 .5 ) 2 8 .6 (2 2 .4 – 3 4 .6 ) 1 3 .1 (1 1 .3 – 2 1 .3 ) 1 5 .9 (1 0 .5 – 2 7 .4 ) P C O 2 (v – a) m m H g 2 9 (1 4 – 5 6 ) 1 3 (7 – 2 2 ) 7 0 (4 0 – 1 0 3 ) 4 6 (2 0 – 1 0 8 ) P C O 2 (v – a) /C O 2 (a – v) m m H g⋅ d L/ m L 1 5 .3 (4 .1 – 4 9 .2 ) 3 .3 (1 .4 – 7 .6 ) 6 5 .2 (3 3 .6 – 1 2 4 .0 ) 5 8 .3 (1 1 .0 – 1 0 8 ) Tr ea tm en t V o lu ve n H ea rt ra te p er m in 1 1 5 (9 3 – 1 2 3 ) 1 4 3 (1 3 1 – 1 5 9 ) 1 3 6 (1 2 3 – 1 4 3 ) 1 5 2 (1 3 3 – 2 0 2 ) R es p ir at o ry ra te p er m in 1 6 (8 – 2 3 ) 1 8 (7 – 1 9 ) 2 7 (8 – 3 5 ) 2 4 (9 – 4 5 ) SA P m m H g 9 1 (8 5 – 9 3 ) 6 9 (5 8 – 7 4 ) 9 9 (9 3 – 1 0 9 ) 9 4 (8 8 – 1 1 7 ) M A P m m H g 6 7 (6 3 – 7 5 ) 4 5 (4 1 – 4 8 ) 7 5 (6 9 – 9 5 ) 7 8 (6 5 – 9 3 ) D A P m m H g 5 2 (4 8 – 6 0 ) 3 7 (3 4 – 3 9 ) 5 6 (5 2 – 7 8 ) 6 2 (4 9 – 7 2 ) La ct at e m m o l/ L 1 .6 (1 .0 – 2 .1 ) 2 .0 (1 .4 – 2 .8 ) 1 .2 (0 .8 – 1 .3 ) 1 .3 (1 .0 – 1 .6 ) B E m m o l/ L − 7 .7 (− 9 .7 to − 5 .6 ) − 8 .7 (− 1 0 .0 to − 7 .3 ) − 6 .9 (− 8 .7 to − 5 .3 ) − 7 .5 (− 8 .7 to − 4 .8 ) P v O 2 m m H g 8 2 (6 5 – 1 4 3 ) 4 7 (3 6 – 5 4 ) 8 9 (6 4 – 1 5 0 ) 1 0 3 (8 7 – 1 3 5 ) C v O 2 m L/ d L 1 0 .7 (9 .5 – 1 2 .0 ) 8 .8 (7 .9 – 1 0 .9 ) 5 .6 (5 .2 – 6 .5 ) 4 .6 (4 .0 – 5 .8 ) O E R % 1 3 .3 (7 .2 – 2 0 .0 ) 3 0 .3 (2 4 .0 – 4 4 .3 ) 1 8 .4 (1 2 .3 – 2 1 .8 ) 1 8 .1 (1 3 .4 – 2 3 .1 4 ) P C O 2 (v – a) m m H g 4 3 (2 0 – 1 0 1 ) 7 (3 – 2 0 ) 5 7 (2 9 – 1 1 4 ) 6 9 (4 4 – 1 0 1 ) P C O 2 (v – a) /C O 2 (a – v) m m H g⋅ d L/ m L 3 1 .2 (9 .0 – 1 1 4 .2 ) 1 .6 (0 .4 – 6 .2 ) 5 2 .7 (1 6 .9 – 1 3 2 .7 ) 6 2 .9 (4 4 .0 – 1 0 3 .5 ) N ot e: D at a co lle ct ed b ef o re co n tr o lle d h em o rr h ag e (T − 1 5 ), im m ed ia te ly af te r h em o rr h ag e b u t b ef o re st ar ti n g fl u id re su sc it at io n (T 0 ), at 6 0 m in u te s o f fl u id re su sc it at io n (T 6 0 ), an d at 1 2 0 m in u te s o f fl u id re su sc it at io n (T 1 2 0 ). D at a p re se n te d as m ed ia n (Q 1 – Q 3 ). A b b re vi at io n s: B E ,b as e ex ce ss ;C v O 2 ,v en o u s co n te n t o f ox yg en ;D A P, d ia st o lic ar te ri al b lo o d p re ss u re ;M A P, m ea n ar te ri al b lo o d p re ss u re ;O E R ,o xy ge n ex tr ac ti o n ra ti o ;P C O 2 (v – a) ,v en o u s- to -a rt er ia lp ar ti al p re ss u re o f ca rb o n d io xi d e ga p ;P C O 2 (v – a) /C O 2 (a – v) ,v en o u s- to -a rt er ia lp ar ti al p re ss u re o f ca rb o n d io xi d e ga p to ar te ri al -t o -v en o u s ox yg en co n te n t ra ti o ;P vO 2 ,v en o u s p ar ti al p re ss u re o f ox yg en ;S A P, sy st o lic ar te ri al b lo o d p re ss u re . 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense 362 ZEILER ET AL. F IGURE 1 Confidence interval plots (95%) of RBC count, platelet count, HCT, and hemoglobin concentrationmeasured over time. Samples were collected at the health check 1week prior to treatments (T− 7d), immediately after the hemorrhage phase (T0), at 60 and 120minutes (T60 and T120, respectively) during the resuscitation phase, and 24 hours (T24h) after T0. The cats were anesthetized and underwent 3 treatments, as follows: (1) NHR, with no controlled hemorrhage nor resuscitation; or controlled hemorrhage followed by (2) lactated Ringer’s solution for resuscitation (LRS); and (3) 6% tetrastarch 130/0.4 (Voluven) for resuscitation. Cats that underwent a controlled hemorrhage phase, followed by a resuscitation phase with LRS and Voluven administered at 60 and 20mL/kg/h, respectively, for 120minutes. The dashed lines represent the upper and lower reference interval for the test published by the clinical pathology laboratory where the tests were done. laboratory were 10.5 (10.3–10.6) and 11.6 (11.1–11.9) seconds, respectively. The PT was significantly longer during LRS and Voluven at T60 and T120 compared to all other time points but not different among the treatments (time: P = 0.028). The aPTT was prolonged dur- ing LRS andVoluven at T60 and T120 compared to all other time points and different fromNHR (treatment × time: P< 0.001). The TEG values for themeasured variables are summarized in Table S3. The R-time did not differ among treatments or over time. Simi- larly, K-time did not differ among treatments or over time. The α-angle was significantly different over time only in cats receiving the NHR and Voluven treatments, but not LRS (time: P = 0.013). Despite the significant differences in α-angle, their median values were all within the laboratory reference intervals for cats (Figure 3). The MA was sig- nificantly smaller during LRS at T60 and T120 and during Voluven at T0, T60, and T120 compared to all other time points, but not different among the treatments (time: P < 0.001). The G-value varied similarly to theMAand also differed over time, but not among treatments (time: P < 0.001). The significant observations in LRS and Voluven over time for theMA and G-value were smaller than the lowest limit of the labo- ratory reference intervals for cats (Figure4). Therewerenodifferences over time or among treatments for lysis 30 and lysis 60. However, median values and rangeswere outside the limits of the laboratory ref- erence intervals for cats after administration of LRS and Voluven over time, compared to NHR (Figure 5). 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense ZEILER ET AL. 363 F IGURE 2 Confidence interval plots (95%) of prothrombin time and activated partial prothrombin time. Samples were collected at the health check 1week prior to treatments (T− 7d), immediately after the hemorrhage phase (T0), at 60 and 120minutes (T60 and T120, respectively) during the resuscitation phase, and 24 hours (T24h) after T0. The cats were anesthetized and underwent 3 treatments, as follows: (1) NHR, with no controlled hemorrhage nor resuscitation; or controlled hemorrhage followed by (2) lactated Ringer’s solution for resuscitation (LRS); and (3) 6% tetrastarch 130/0.4 (Voluven) for resuscitation. Cats that underwent a controlled hemorrhage phase, followed by a resuscitation phase with LRS and Voluven administered at 60 and 20mL/kg/h, respectively, for 120minutes. The dashed lines represent the upper and lower reference interval for the test published by the clinical pathology laboratory where the tests were done. 4 DISCUSSION Overall, the coagulation profilewas normal in the cats during their con- scious states (health check and at 24 h after controlled hemorrhage) and after the hemorrhage phase during all treatments. Themain obser- vations were somewhat counterintuitive in that the screening assays were prolonged but, unexpectedly, the R-time and K-time of the TEG were within reference intervals. Regardless, all assays detected a state of hypocoagulability in the controlled hemorrhage and resuscitation treatments. F IGURE 3 Confidence interval plots (95%) of the R-time, K-time, and alpha angle measured by thromboelastography over time. Samples were collected at the health check 1week prior to treatments (T− 7d), immediately after the hemorrhage phase (T0), at 60 and 120minutes (T60 and T120, respectively) during the resuscitation phase, and 24 hours (T24h) after T0. The cats were anesthetized and underwent 3 treatments, as follows: (1) NHR, with no controlled hemorrhage nor resuscitation; or controlled hemorrhage followed by (2) lactated Ringer’s solution for resuscitation (LRS); and (3) 6% tetrastarch 130/0.4 (Voluven) for resuscitation. Cats that underwent a controlled hemorrhage phase, followed by a resuscitation phase with LRS and Voluven administered at 60 and 20mL/kg/h, respectively, for 120minutes. The dashed lines represent the upper and lower reference interval for the test published by the clinical pathology laboratory where the tests were done. 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense 364 ZEILER ET AL. F IGURE 4 Confidence interval plots (95%) of themaximum amplitude andG-valuemeasured by thromboelastography over time. Samples were collected at the health check 1week prior to treatments (T− 7d), immediately after the hemorrhage phase (T0), at 60 and 120minutes (T60 and T120, respectively) during the resuscitation phase, and 24 hours (T24h) after T0. The cats were anesthetized and underwent 3 treatments, as follows: (1) NHR, with no controlled hemorrhage nor resuscitation; or controlled hemorrhage followed by (2) lactated Ringer’s solution for resuscitation (LRS); and (3) 6% tetrastarch 130/0.4 (Voluven) for resuscitation. Cats that underwent a controlled hemorrhage phase, followed by a resuscitation phase with LRS and Voluven administered at 60 and 20mL/kg/h, respectively, for 120minutes. The dashed lines represent the upper and lower reference interval for the test published by the clinical pathology laboratory where the tests were done. The prolonged PT and aPTT could have arisen from hemodilu- tion, whereby all coagulation factors were diluted enough to cause the derangement.4,5 Furthermore, the endothelial glycocalyx degrades after hemorrhage,22,23 as well as after administering fluids for resus- citation, and this degradation results in vitro prolongation of PT and aPTT.24 Indeed, the derangements were similar in cats during LRS or Voluven in the present study. The effects of LRS and Voluven were especially profound in the aPTT, a test that assesses the intrinsic and common coagulation pathways.15 The R-time of the TEG provides a F IGURE 5 Confidence interval plots (95%) of clot lysis at 30 and 60minutes measured by thromboelastography over time. Samples were collected at the health check 1week prior to treatments (T− 7d), immediately after the hemorrhage phase (T0), at 60 and 120minutes (T60 and T120, respectively) during the resuscitation phase, and 24 hours (T24h) after T0. The cats were anesthetized and underwent 3 treatments, as follows: (1) NHR, with no controlled hemorrhage nor resuscitation; or controlled hemorrhage followed by (2) lactated Ringer’s solution for resuscitation (LRS); and (3) 6% tetrastarch 130/0.4 (Voluven) for resuscitation. Cats that underwent a controlled hemorrhage phase, followed by a resuscitation phase with LRS and Voluven administered at 60 and 20mL/kg/h, respectively, for 120minutes. The dashed lines represent the upper and lower reference interval for the test published by the clinical pathology laboratory where the tests were done. similar measure, but unexpectedly its value remained within the nor- mal reference interval for cats during all treatments at all time points. The R-time has demonstrated correlation to aPTT and especially PT when both assays are initiated using tissue factor, like in our study. Thus, the R-time has been associatedwith soluble clotting factor activ- ity; however, this correlation, despite being described, has not been repeatable in all studies.25 Regardless,weexpectedaprolongedR-time at T60 and T120 during LRS and Voluven treatments. The unexpected difference in these 2 assays could possibly be attributed to the use 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense ZEILER ET AL. 365 of different reagents and activators in aPTT and TEG assays, because if dilution was the only factor, then we would have expected similar findings. It should be noted that the substantial variability in PT, aPTT, and R-times in treatments LRS and Voluven at T60 and T120 can also explain the contradicting discrepancy between these variables. The authors speculate that a larger sample size would potentially mitigate the variability, which can allow for an accurate assessment of agree- ment between these variables. However, in anemic dogs, the results of viscoelastic tests in coagulation have indicated that they have a hyper- coagulability identified by short R-time, short K-time, and increased MA,2,26 similar to observations of the present study, whereby shorter than expected R-times at T60 and T120 during LRS and Voluven treat- ments when the HCTs were at their lowest were observed. However, MA, at these time points, was lower than the lowest reference inter- val level, unlike reports on anemic dogs.2,26 The low MA observed in the present study could be explained by the decrease in the platelet count at these time points.25 The platelet counts were corrected and standardized in an in vitro dog study2 or positively correlated with maximum clot firmness (a thromboelastometry variable similar toMA) in an in vivo dog study.26 Furthermore, although not measured in our study, the concentration of fibrinogen and its contribution to the fibrin meshwork structure also influence the MA.26 In our study, we spec- ulate that a dilutional coagulopathy can contribute to low fibrinogen concentration, weak fibrin meshwork structure, and low MA. The low HCT, however, is not the only factor related to a hypercoagulability as overall blood viscosity might also be a factor. The viscosity of whole blood is mainly attributed to the RBC mass under normal physiologi- cal conditions, but plasma proteins, especially fibrin, also contribute to viscosity.2 When there is a low HCT and low blood viscosity, artificial hypercoagulability occurs, while a lowHCT and normal viscosity cause hypocoagulability.2 Aswith the concernofdata variability of thePTand aPTT and R-time data, the other TEG measurements had a large vari- ability, andwe speculate that a larger sample sizewould havemitigated this variability. The fibrinolytic phaseof theTEGassay (lysis 30and lysis 60) is scantly reported on it cats, which makes interpreting this phase of the assays a challenge. In our study, some of the lysis 30 and 60were above the reference interval at T60 and T120, regardless of treatment. Values of maximum lysis (ROTEM variable) in healthy cats were higher than expected, and this was due to clot retraction rather than true clot lysis and can explain out observation.27 Coagulopathies were detected at T60, which translates to total volumes of LRS and Voluven infused at this time point of 60 and 20 mL/kg, respectively. The approximate administration ratios (resus- citation fluid to blood lost volumes) were 2.2:1 and 0.7:1 for LRS and Voluven, respectively, at this time point. The fluid volumes that were administered at this time point were likened to the recommended conventional shock dose rates for cats, but less than the frequently recommended ratios.28 These findings have potentially far-reaching clinical implications because if the intravascular compartment is resus- citated using these conventional liberal resuscitation guidelines, then coagulopathies can be anticipated. Furthermore, the utilization of a limited-fluid volume resuscitation protocol whereby hypertonic saline (2mL/kg) alone or in combinationwith a hydroxyethyl starch (2mL/kg) is administered after an initial isotonic crystalloid bolus (15–20mL/kg) may be an alternative therapy for cats unresponsive to conventional fluid therapy protocols.29 Furthermore, the endothelial glycocalyx is degraded by hemorrhage and by fluid resuscitation regardless of volumes being administered has prompted investigation to find an alternative resuscitation fluid.22–24 In a rat model, administer- ing fresh frozen plasma improved intravascular volume and restored the endothelial glycocalyx, which suggests fresh frozen plasma is a possible alternative resuscitation fluid.22 In the present study, cats received very liberal fluid volumes after severe hemorrhage but still had normal coagulation and hematology profiles a day after treat- ments. Therefore, we speculate that healthy cats have a high fluid tolerance and, unexpectedly, do not require emergency interventions (eg, diuretic treatment) to normalize their total body water and HCT after a hemorrhagic episode.16 However, cats with subclinical car- diomyopathy may be less fluid tolerant, and screening for cardiac disease is recommended before drafting a fluid plan for resuscitation andmaintenance. The study had notable limitations. The crossover design meant that an atraumatic hemorrhage model was used, and this may limit the translatability of this study to clinical practice where trauma to the vasculature can be associatedwith natural occurring hemorrhage. Fur- thermore, it is unknown if this crossover study had a carryover effect of preconditioning the cats to subsequent severe hemorrhage events and hypoxemia. No prehemorrhage blood sample was collected for hemo- static analysis, and this limits the interpretation of distinguishing what effect general anesthesia had on coagulation and hematology from the effect of hemorrhage. The TEG assay used in this study was activated using tissue factor, similar to a PT assay, but future studies should plan to include kaolin-activated TEGs to identify if there is a relationship between R-time and aPTT assays. The blood sampling method used during the health check (needle and syringe) was different from that used during subsequent time points (aspiration from catheter), which is not ideal.11 However, therewere no differences in the tests of coagu- lation during the health check and the day after treatments, suggesting that the sampling technique did not cause deviations in outcomes of coagulation assays. A complete investigation into the pathophysiology of the derangements (platelet function analysis, factor concentration determination, etc) was not conducted because of study budget con- straints. Also, total proteins and fibrinogen concentrations were not measured. Therefore, we cannot state with confidence that other fac- tors, other than hemodilution, do not play a role in the coagulopathies observed in the present study. The sample size was small and thus had the power to reliably detect only large effects. However, the obser- vations herein will assist future researchers in estimating adequate sample sizes to validate these observations under various clinical con- ditions. The calculated cardiopulmonary variables to aid in quantifying hemorrhagic shock are larger compared to expected ranges of dog hemorrhage models, and this can be because the cats were provided 100%oxygen during the anesthetic, thereby altering arterial to venous gradients compared to breathing room air of 21% oxygen. 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense 366 ZEILER ET AL. 5 CONCLUSIONS Coagulopathies consistentwith laboratory and clinical hypocoagulabil- ity were detected during the resuscitation phase in anaesthetized cats after hemorrhage. There were no differences in the coagulopathies between cats that received lactated Ringer’s solution and Voluven. Further research is required to identify the mechanisms and patho- physiology responsible for the coagulopathies observed in the present study. AUTHOR CONTRIBUTIONS GarethE. Zeiler, BrightonT.Dzikiti, PeterKamerman, RoxanneK. Buck, and Andrea Fuller participated in study design. Gareth E. Zeiler, Rox- anne K. Buck, and Friederike Pohlin completed the data collection. Gareth E. Zeiler, Brighton T. Dzikiti, Friederike Pohlin, Peter Kamer- man, and Andrea Fuller analyzed and interpreted the data. All authors contributed withmanuscript drafting and editing. ACKNOWLEDGMENTS The authors would like to thank the staff members of the UPBRC who assisted in the PhD research project. We would also like to thank the following for their financial contributions: the SouthAfricanVeterinary Foundation, the Health and Welfare Sector Education and Training Authority (HWSETA) fund, the University of Pretoria Research Devel- opmentProgram, and theSouthAfricanNationalResearchFoundation. CONFLICT OF INTEREST STATEMENT The authors declare no conflicts of interest. ORCID GarethE. Zeiler BVSc(Hons),MMedVet(Anaesth), PhD,DECVECC, DECVAA,DACVAA https://orcid.org/0000-0001-7653-7726 Notes aHill’s Science Plan Adult Dry Cat Food (chicken or tune flavor), Hill’s Pet Nutrition Ltd., Hout Bay,Western Cape. bhttp://www.jerrydallal.com/random/randomize.htm. cTemgesic 0.3 mg/mL, Reckitt Benckiser Healthcare, Johannesburg, Gaut- eng. d Jelco I.V. Cathater Radiopaque (22 gauge), Smith Medical International, Johannesburg, Gauteng. eAlfaxan-CDRTU; Afrivet, Midrand, Gauteng. fPVC endotracheal tube (4.0 to 4.5 mm internal diameter), Teleflex Incorporated,Midrand, Gauteng. gCompact paediatric breathing system (15 mm internal diameter), Inter- surgical, Midrand, Gauteng. h Isofor; Safeline Pharmaceuticals, Midrand, Gauteng. i EC 5 Isoflurane Vaporiser, Safeline Pharmaceuticals, Midrand, Gauteng. jBiotaine in alcohol, B-Braun, Johannesburg, Gauteng. k Lactated Ringer’s Solution, Fresenius Kabi, Midrand, Gauteng. l Infusomat Space, B-Braun, Johannesburg, Gauteng. m Infusomat Space Set, B-Braun, Johannesburg, Gauteng. nDatex-Ohmeda Cardiocap 5; GEHealthcare, Helsinki, Finland. oArrow arterial catheterization set (22 Gauge, 50 mm), Teleflex Incorpo- rated, Midrand, Gauteng. pVoluven, Fresenius Kabi, Midrand, Gauteng. qOmnifix syringe (20mL), B-Braun, Johannesburg, Gauteng. r JMS blood bag (450mL), JMS Singapore, AngMoKio, Central Singapore. sBloodStop iX, Life Science Plus, Palo Alto, CA. tMonoPlus 5/0, B-Braun, Johannesburg, Gauteng. uPetcam; CiplaVet, Midrand, Gauteng. v Sodium citrate 0.109M BD Vacutainers, Becton Dickinson and Company, Plymouth, Devon. wEDTABDVacutainers, BectonDickinson andCompany, Plymouth,Devon. xHaemoscope TEG 5000 Thrombelastograph Hemostasis Analyzer, Haemonetics, Braintree, Boston,MA. yACL Elite,Werfen, Barcelona, Barcelona. zAdvia 2120, Siemens Healthineers, Erlangen, Bavaria. aaCaCL2 buffer (0.020M), HemosIL Instrumentation Laboratory Company, Bedford,MA. abDade, Innovin, Siemens Diagnostics, Deerfield, IL. acRecombiPlasTin 2G, HemosIL Instrumentation Laboratory Company, Bedford,MA. adSynthAsil, HemosIL Instrumentation Laboratory Company, Bedford, MA. aeMiniTab 18.1, Minitab Inc., State College, PA. 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Limited fluid volume resuscitation (LFVR) in severe shock unresponsive to initial fluid challenge: a pilot study in 10 cats. Vet Anaesth Analg. 2018;45:782-787. SUPPORTING INFORMATION Additional supporting information can be found online in the Support- ing Information section at the end of this article. How to cite this article: Zeiler GE, Dzikiti BT, Rioja E, et al. Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitationmodel using lactated Ringer’s solution or 6% tetrastarch 130/0.4. J Vet Emerg Crit Care. 2024;34:356–367. https://doi.org/10.1111/vec.13376 14764431, 2024, 4, D ow nloaded from https://onlinelibrary.w iley.com /doi/10.1111/vec.13376 by South A frican M edical R esearch, W iley O nline L ibrary on [12/08/2024]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense https://doi.org/10.1111/vec.13376 Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitation model using lactated Ringer’s solution or 6 tetrastarch 130/0.4 Abstract 1 | INTRODUCTION 2 | MATERIAL AND METHODS 2.1 | Animals 2.2 | Study procedures 2.3 | Data collection 2.4 | Data analysis 3 | RESULTS 4 | DISCUSSION 5 | CONCLUSIONS AUTHOR CONTRIBUTIONS ACKNOWLEDGMENTS CONFLICT OF INTEREST STATEMENT ORCID Notes REFERENCES SUPPORTING INFORMATION