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Objective: To determine if Irish Wolfhounds (IWs), like other sighthounds, are hyperfibrinolytic compared with nonsighthound dogs using 2 native and tissue plasminogen activator (tPA)-enhanced viscoelastic assays, one that is whole blood-based (viscoelastic coagulation monitor [VCM]) and the other that is plasma-based thromboelastography (TEG)., Design: Cohort study., Setting: University teaching hospital., Animals: A convenience sample of 27 IWs recruited from the Irish Wolfhound Association of New England Specialty and the local community, and 27 healthy, age-matched, large-breed control dogs., Interventions: None., Measurements and Main Results: Blood samples including CBC, biochemistry, traditional coagulation, and viscoelastic testing were collected from IWs and control dogs. Twelve IWs had viscoelastic testing. IWs had lower fibrinogen concentrations (215.5 ± 57.8 vs 251.4 ± 64.5 mg/dL, P = 0.034) and formed weaker clots on both whole-blood VCM and plasma TEG assays (maximum clot firmness [VCM-MCF] = 39.4 [25.1-48.8] vs 48.5 [34.6-57.3], P = 0.0042; maximum amplitude [TEG-MA] = 22.7 [14.7-33.6] vs 32.2 [26.9-42.0], P < 0.0001). IWs were hyperfibrinolytic compared with control dogs on VCM whole-blood assays, with 25 U/mL tPA (lysis at 30 min [VCM-LI30] = 68.1 [0-100] vs\ 99.9 [63.3-100], P = 0.0009; lysis at 45 min [VCM-LI45] = 31.0 [0-100] vs 98.1 [38.4-100], P = 0.0002) but hypofibrinolytic compared with controls on TEG plasma assays with 50 U/mL tPA (lysis at 30 min [TEG-LY30] = 45.7 [4.6-94.6] vs 93.7 [12.3-96.5], P = 0.0004; lysis at 60 min [TEG-LY60] = 68.7 [29.7-96.8] vs 95.7 [34.4-97.6], P = 0.0003). Minimal fibrinolysis was measured on whole-blood VCM or plasma TEG assays without the addition of tPA, and there were no differences between the 2 groups., Conclusions: Weaker clots were found in IWs than control dogs. With the addition of tPA, IWs had evidence of hyperfibrinolysis on whole-blood VCM assays and hypofibrinolysis on plasma TEG assays compared with control dogs. Without the addition of tPA, however, both groups of dogs showed minimal fibrinolysis on viscoelastic testing., (© Veterinary Emergency and Critical Care Society 2024.)

Objectives: To determine platelet function and assess fibrinolysis in dogs following trauma using multiple electrical impedance aggregometry and a modified thromboelastographic (TEG) technique. To determine if the severity of trauma, as assessed by the Animal Trauma Triage (ATT) score and clinicopathological markers of shock, is associated with a greater degree of platelet dysfunction and fibrinolysis., Setting: University teaching hospital., Animals: Twenty client-owned dogs with trauma (occurring <24 h prior to admission and blood sampling) and ATT score of >4 were prospectively recruited. A control group of 10 healthy dogs was included., Interventions: None., Measurements and Main Results: Platelet function was measured using multiple electrode platelet aggregometry (MEPA) utilizing arachidonic acid, ADP, and collagen agonists. Fibrinolysis was assessed in citrated whole blood with the addition of tissue plasminogen activator (tPA; 50 U/mL) using kaolin-activated TEG. Conventional statistical analysis was performed to compare coagulation parameters between the groups and assess linear correlations. Median (interquartile range) ATT score was 5 (5-7), and 65% (n = 13) of dogs suffered polytrauma. Mean (± SD) time from trauma to blood sampling was 9 hours (± 6). Median (interquartile range) shock index and plasma lactate concentration were 1.1 (0.7-2.0, n = 16) and 2.9 mmol/L (0.9-16.0, n = 18), respectively. Four dogs did not survive to discharge (20%). There were no differences between the trauma and control group coagulation variables. A moderate negative correlation between ATT score and area under the curve for ADP was found (P = 0.043, r 2  = -0.496)., Conclusions: Preliminary evaluation of platelet function measured by MEPA, and fibrinolysis measured by tPA-modified TEG, is not significantly different in this population of dogs with traumatic injury compared to healthy dogs., (© 2023 The Authors. Journal of Veterinary Emergency and Critical Care published by Wiley Periodicals LLC on behalf of Veterinary Emergency and Critical Care Society.)

Objective: To describe hemostatic derangements associated with canine anaphylaxis and to assess for association with syndrome severity., Design: Prospective observational study., Setting: University teaching hospital., Animals: Twenty-seven client-owned dogs, recruited from November 2018 to January 2022, diagnosed with anaphylaxis of varying severity were included. Study inclusion required presentation <6 hours after initiation of clinical signs, no medications or history of illness within the prior 2 weeks, lack of comorbidities expected to affect hemostasis, and lack of a disease state that could alternatively explain the clinical presentation., Interventions: Blood samples were collected within the first hour of presentation for CBC, serum biochemistry, prothrombin time (PT), activated partial thromboplastin time (aPTT), and viscoelastic coagulation testing for use with a cartridge-based point-of-care device., Measurements and Main Results: Clotting time and clot formation time were prolonged, alpha angle and maximum clot firmness were decreased, PT and aPTT were prolonged, and platelet counts were lower in severe cases compared to mild and moderate cases. There were no differences for any parameter between mild and moderate cases. The presence or absence of abdominal effusion was not associated with hemostatic status., Conclusions: Global hemostatic derangements consistent with hypocoagulability are a prominent feature of severe anaphylaxis in dogs and should be considered for routine evaluation., (© 2023 The Authors. Journal of Veterinary Emergency and Critical Care published by Wiley Periodicals LLC on behalf of Veterinary Emergency and Critical Care Society.)

Objective: To evaluate a point-of-care viscoelastic coagulation monitor (VCM Vet) for use in horses by assessing variability between devices and establish reference intervals (RIs) for healthy adult horses., Design: Prospective observational study., Setting: Two university teaching hospitals., Animals: Healthy adult horses (n = 68)., Interventions: None., Measurements and Main Results: Blood collected by direct jugular venipuncture was applied directly from the syringe into 2 VCM Vet cassettes to establish coefficients of variation (CVs) and RIs for reported parameters of clotting time (CT), clot formation time (CFT), alpha angle, amplitude at 10 and 20 minutes, maximum clot firmness, and lysis index at 30 and 45 minutes. CVs for each parameter were within clinical tolerance. There was a significant difference in CT between institutions (P < 0.001). Differences in CV were found between institutions for CT (P = 0.003) and CFT (P = 0.01). Healthy horse RIs were calculated for the overall data set and each individual institution. Calculated RIs were as follows: CT, 255.6-1233.9 seconds; CFT, 89.4-581 seconds; alpha angle, 11.4-53.6°; maximum clot firmness, 18-37.7; lysis index at 30 minutes, 97.3%-102.1%; lysis index at 45 minutes, 80.8%-103.3%; amplitude at 10 minutes, 8.7-28.3; and amplitude at 20 minutes, 17.4-35.7., Conclusions: VCM Vet is a repeatable and practical option for rapid point-of-care assessment of hemostasis in horses but has a wide RI and is susceptible to variability. Establishment of institution-specific RIs is recommended., (© Veterinary Emergency and Critical Care Society 2023.)

Objective: To estimate the point prevalence and duration of hyperfibrinolysis (HF) in dogs undergoing surgical control of spontaneous hemoperitoneum (SHP)., Design: Prospective observational study., Setting: Single veterinary teaching hospital., Animals: Forty-five client-owned dogs with SHP were screened for HF. Eighteen HF dogs treated surgically were studied., Interventions: None., Measurements and Main Results: Dogs with SHP and evidence of shock admitted for surgical control of hemorrhage were screened for HF. Blood samples were collected for PCV, total plasma protein, platelet count, and thromboelastography with 50 U/mL of tissue plasminogen activator at presentation and every 8 hours postoperatively until 72 hours, discharge, or death. HF was defined as a tissue plasminogen activator-activated thromboelastography lysis percentage measured 30 minutes after maximum amplitude (LY30) of ≥20%. LY30 values were compared to a cohort of samples obtained from healthy dogs (n = 22). The point prevalence of HF in all dogs screened was 40% (18/45 dogs), and the mean LY30 at baseline for HF dogs was 48.9% (±24.2%), which was significantly higher than that of control dogs (4.8% ± 7.1%, P < 0.001) and non-HF dogs (1.9% ± 5.7%, P < 0.001). In HF dogs, there was a significant decrease in LY30 between baseline and 8 hours (P < 0.0001) and between 8 and 16 hours (P = 0.035) but no significant change thereafter. LY30 at 8 hours (4%, range: 0%-23.4%) was not statistically different from control dogs (6.5%, range: 1.2%-32.8%, P = 0.664) suggesting early resolution of HF in this population. Only 2 of 18 dogs were persistently hyperfibrinolytic at 24 hours. Malignancy was diagnosed in 12 of 18 dogs (66.6%), while a benign etiology occurred in 6 of 18 dogs (33.3%). All HF dogs survived to discharge., Conclusions: HF occurs in some dogs with hypovolemic shock due to hemoperitoneum but resolves rapidly following surgical control of bleeding without antifibrinolytic medications. Routine postoperative use of antifibrinolytics in dogs with hemoperitoneum in dogs undergoing surgical control of bleeding may not be warranted., (© Veterinary Emergency and Critical Care Society 2023.)

Objective: To compare viscoelastic parameters between healthy control dogs and dogs with primary immune-mediated hemolytic anemia (pIMHA) using a new, point-of-care viscoelastic coagulation monitor (VCM). a DESIGN: Retrospective study from 2017 to 2021., Setting: Three regional private referral centers., Animals: Eighteen client-owned dogs with pIMHA and 33 healthy control dogs. pIMHA dogs were defined based on established criteria., Interventions: None., Measurements and Main Results: Medical records of dogs with pIMHA and VCM performed at diagnosis from 2017 to 2021 and apparently healthy control dogs voluntarily enrolled in the blood donor program from 2017 to 2018 were reviewed. For the healthy control dogs, consent was obtained to perform VCM in addition to traditional screening. Compared to healthy control dogs, dogs with pIMHA had mean VCM parameters consistent with hypercoagulability, demonstrated by lower mean (SD) clot formation time (108 s [30] vs 233 s [55]; P < 0.0001), higher mean alpha angle (62 degrees [6] vs 52 degrees [6]; P < 0.0001), higher mean maximum clot formation (49 VCM units [11] vs 32 VCM units [5]; P < 0.0001), higher mean amplitude at 10 minutes (40 VCM units [11] vs 19 VCM units [3]; P < 0.0001), and higher mean amplitude at 20 minutes (47 VCM units [11] vs 25 VCM units [4]; P < 0.0001). pIMHA dogs also had significantly higher median (interquartile range) lysis index at 30 minutes (100% [100-100] vs 98% [90-100]; P < 0.0001). When compared to 3 established normal canine reference intervals, dogs with pIMHA had a significantly higher proportion of VCM variables (48%-57%) consistent with hypercoagulability, and a significant percentage of pIMHA dogs (78%-89%) had VCM tracings consistent with hypercoagulability overall, irrespective of the interval utilized for interpretation., Conclusions: This study demonstrates hypercoagulability in dogs with pIMHA when compared to healthy control dogs using VCM. Prospective evaluation is warranted to further characterize these findings as well as to evaluate their clinical impact., (© Veterinary Emergency and Critical Care Society 2022.)

Objectives: To compare the efficacy of 2 equine-origin antivenom products on correction of coagulation abnormalities noted on thromboelastography (TEG) caused by Crotalus atrox venom in vitro., Design: Prospective in vitro controlled study., Setting: Veterinary teaching hospital., Animals: Six healthy dogs., Interventions: Blood from each dog was used for 4 separate kaolin-activated TEG analyses: A negative control (blood-saline) and positive control (blood-Crotalus atrox venom) were used to assess the dog's normal coagulation and the effect of venom on TEG parameters. Thromboelastographic analyses were then run with blood, venom, and either Argentinian or North American antivenom. All TEG analyses from each dog were compared for efficacy., Measurements and Main Results: The mean R values between the North American antivenom and negative controls were not significantly different (P = 0.681), but were significantly different (P = 0.024) between the Argentinian antivenom and negative controls. The mean fibrinolysis values measured 30 minutes after maximum amplitude achieved between the North American antivenom and negative controls were not significantly different (P = 0.198), but were significantly different (P < 0.001) between the Argentinian antivenom and negative controls. The mean K values between the Argentinian antivenom and negative controls were not significantly different (P = 0.274), but were significantly different (P = 0.043) between the North American antivenom and negative controls., Conclusions: The North American antivenom normalized time to clot formation and fibrinolysis, while the Argentinian antivenom normalized rate of clot formation. Further studies in naturally envenomated patients are necessary to determine if these in vitro results would translate into different clinical outcomes., (© Veterinary Emergency and Critical Care Society 2022.)

Objective: To compare the impact of an IV bolus of hydroxyethyl starch 130/0.4 (HES) or hypertonic saline 7.5% (HS) on hemostasis in dogs resuscitated for gastric-dilation-volvulus (GDV)., Design: Open-label, parallel-group randomized clinical trial., Animals: Twenty-three client-owned dogs., Interventions: Dogs affected by GDV and shock were randomly assigned to receive HES at 10 mL/kg or HS at 4 mL/kg every 15 minutes. Blood samples were collected for blood gas analysis, PCV, total plasma protein, albumin, standard coagulation profile, and thromboelastometry (ROTEM) at baseline (T0) and at the end of bolus (T1). To assess the differences between the 2 groups at T1, Student's t-test or Wilcoxon rank-sum test was used. To evaluate the differences between T0 and T1, ANOVA for paired data or Wilcoxon matched-pairs signed-ranks test was used. P < 0.05 was considered significant., Measurement and Main Results: Hemostasis was evaluated by means of prothrombin time, activated partial thromboplastin time, fibrinogen, and ROTEM. The study included 13 dogs in the HES group and 10 dogs in the HS group. Differences were found between groups at T1: increase in clotting time (P = 0.018) and decrease in fibrinogen level (P = 0.021) in the HS-treated group. Between T0 and T1, there were differences for the HES group: increase in clot formation time (P = 0.046), decrease in maximum clot firmness (P = 0.002) in ex-TEM profile, and decrease in maximum clot firmness (P = 0.0117) in fib-TEM profile. Between T0 and T1, the following differences were noted for the HS group: increase in clotting time (P = 0.048) and clot formation time (P = 0.0019), decrease in maximum clot firmness (P = 0.031) and α angle (P = 0.036) in ex-TEM profile, decrease in α angle (P = 0.036) in in-TEM profile, and decrease in maximum clot firmness (P = 0.017) in fib-TEM profile., Conclusion: In dogs affected by GDV, HES or HS infusion caused a similar tendency toward hypocoagulability, with few differences between the 2 groups., (© Veterinary Emergency and Critical Care Society 2021.)

Objective: To determine the hemostatic potential of canine chilled whole blood maintained at clinically relevant storage conditions., Design: In vitro experimental study., Setting: Government blood and coagulation research laboratory and government referral veterinary hospital., Animals: Ten healthy Department of Defense military working dogs., Interventions: One unit of fresh whole blood was collected from each of 10 military working dogs using aseptic technique. Blood was maintained in a medical-grade refrigerator for 28 days at 4°C (39°F) and analyzed before refrigeration (day 0) and after (days 2, 4, 7, 9, 11, 14, 21, and 28)., Measurements and Main Results: Ten units of canine blood were analyzed with whole blood platelet aggregation, thromboelastography, CBC, biochemical analysis, blood gas, and prothrombin/activated partial thromboplastin/fibrinogen assay. Clotting strength of chilled blood was maintained up to 21 days despite significant decreases in platelet aggregation to ADP, collagen, or γ-thrombin, significant prolongation of prothrombin and activated partial thromboplastin times, and reduced speed of clot formation (K time, alpha angle). Fibrinogen concentration, WBC, RBC, and platelet counts did not change over time., Conclusions: Chilled canine whole blood loses a small percentage of clot strength through 21 days of refrigerated storage. Further research is needed to determine if this hemostatic potential is clinically relevant in hemorrhaging dogs who require surgical intervention or are exposed to traumatic events., (© Veterinary Emergency and Critical Care Society 2021.)

Objective: To evaluate the effects of 6% hydroxyethyl starch 130/0.4 (HES) and a polyionic isotonic crystalloid (CRYS) on standard coagulation tests and rotational thromboelastometry (ROTEM) in dogs with spontaneous hemoperitoneum (SHP)., Design: Prospective randomized open-label clinical study., Setting: University teaching hospital., Animals: Forty-two client-owned dogs presented with SHP., Interventions: Dogs diagnosed with SHP and hypovolemic shock were randomly allocated to receive HES (10 mL/kg, n = 22) or CRYS (30 mL/kg, n = 20) intravenously over 20 minutes for hemodynamic stabilization., Measurements and Main Results: Parameters measured before (T 0 ) and after (T 1 ) treatment were HCT, platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen concentrations, and extrinsic activated (EXTEM), intrinsic activated (INTEM), and extrinsic activated with platelet inhibition ROTEM assays. Data were analyzed as absolute values and as the percentage change from T 0 to T 1 . No significant differences between groups were detected in any variable at T 0 , and for HCT, platelet counts, prothrombin time, activated thromboplastin time, and fibrinogen concentrations at T 1 . Clot formation time in EXTEM was significantly prolonged (P = 0.037), and maximum clot firmness was significantly decreased (P = 0.038) in the HES group compared to the CRYS group at T 1 . The percentage change in EXTEM clotting time (P = 0.012) and INTEM clot formation time (P = 0.031) was greater after HES than CRYS. Lysis indices remained at 100% for all ROTEM assays in both groups., Conclusion: Compared to a 3-fold volume of CRYS, administration of HES was associated with impairment in ROTEM parameters in dogs with SHP, but no evidence of hyperfibrinolysis was detected., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: To evaluate a panel of coagulation assays for their potential utility in rivaroxaban monitoring as alternatives to the rivaroxaban-specific anti-Xa activity (RIVA)., Design: Prospective experimental study., Setting: University research laboratory., Animals: Five healthy neutered male Beagles., Interventions: Dogs were administered a median dose of 1.8 mg/kg rivaroxaban (range, 1.6-1.8 mg/kg) orally once daily for 2 consecutive days as part of a pharmacodynamic study. Blood was collected from a preplaced jugular catheter at time points relative to their rivaroxaban administration (0, 2, 4, 8, 24, 36, and 48 h) for measurement of RIVA, prothrombin time (PT), activated partial thromboplastin time, RapidTEG, and thrombin generation variables., Measurements and Main Results: One hundred forty data points were available for analysis. There was poor correlation between RIVA and RapidTEG variables: R time (R) (min) (r = 0.554, P < 0.0001), K time (K) (min) (r = -0.204, P = 0.016), alpha angle (degrees) (r = 0.152, P = 0.073), Maximum amplitude (MA) (mm) (r = 0.106, P = 0.215), and G value (G) (dynes/s) (r = 0.108, P = 0.205). A good correlation was noted between thrombin generation variables and RIVA: lag time (min) (r = 0.827, P < 0.0001), peak (nM) (r = -0.752, P < 0.0001), and endogenous thrombin potential (nM·min) (r = -0.762, P < 0.0001). There was an excellent correlation between PT and RIVA (r = 0.915, P < 0.0001) and a good correlation between activated partial thromboplastin time and RIVA (r = 0.772, P < 0 .0001)., Conclusions: Of all the coagulation tests investigated, the PT correlated best with RIVA. There is potential for PT being a convenient second-line monitoring option in dogs receiving rivaroxaban, but further work is necessary to validate other PT assays. Thromboelastography performed with strong activators correlated poorly with anti-Xa activity., (© Veterinary Emergency and Critical Care Society 2020.)

Objectives: To describe 2 cases of boomslang (Dispholidus typus) envenomation in dogs, with thromboelastographic evaluation performed both pre- and postadministration of monovalent antivenom, and to contrast the clinical application of thromboelastography (TEG) with that of conventional coagulation testing in 1 of these cases for monitoring coagulation status in dogs suffering from such envenomation., Case Series Summary: Two dogs, a Weimeraner and a Dachshund, were referred, on separate occasions, for stabilization and treatment following observed boomslang envenomation. Initial physical examination revealed minor bleeding from the bite wound site in both dogs, along with mild swelling of the surrounding tissue. The Weimeraner also demonstrated bleeding from the gingival margin and had pale mucous membranes at time of presentation. Findings consistent with a diagnosis of disseminated intravascular coagulation (DIC) were noted on conventional coagulation testing. TEG tracings in both dogs revealed a hypocoagulable state preadministration of monovalent antivenom, followed by return to a normocoagulable state immediately postadministration, along with resolution of clinical bleeding. Both dogs were successfully discharged from the hospital, with no adverse reactions, either acute or delayed being noted., New or Unique Information Provided: Boomslang envenomation (hemotoxic snake venom) in dogs is rare, with currently only 3 cases in the literature. Herein, we document a further 2 cases and contrast changes on TEG with that noted on a routine hemostatic testing profile in 1 of these cases, to assess overall coagulation status both pre- and postadministration of antivenom., (© Veterinary Emergency and Critical Care Society 2020.)

Objectives: To evaluate the in vitro efficacy of specific Daboia (Vipera) palaestinae (Dp) antivenom or fresh frozen plasma (FFP) against Dp venom-induced hemostatic changes DESIGN: In vitro study., Setting: Laboratory of a university referral hospital., Animals: Five healthy dogs., Interventions: Rotational thromboelastometry (including recombinant tissue factor or kaolin activators [EXTEM and INTEM, respectively]) and conventional hemostatic tests were evaluated in citrated whole blood samples that underwent 4 treatments: (1) no additives (control); (2) 15 μg of Dp venom; (3) 15 μg of Dp venom and 10 μL of specific Dp antivenom; (4) 15 μg of Dp venom and 0.3 mL of FFP. A linear mixed-effects regression model was used to compare results between each treatment and the control., Measurements and Main Results: Dp-venom engendered statistically significant (P < 0.05) EXTEM changes in 8/17 variables, all indicative of hypercoagulability, which were negated by antivenom but not with FFP. Similarly, Dp-venom induced hypercoagulable, hyperfibrinolytic changes in 12 of 17 INTEM variables, of which only 5 of 12 were negated by antivenom but not with FFP. Fibrinogen concentration was decreased, and the activated partial thromboplastin time (aPTT) was shortened (P < 0.05 for both) in all treatments compared to the control., Conclusions: This study demonstrated the ephemeral procoagulant phase of Dp envenomation for the first time. Many venom-induced thromboelastometric changes were reversed by specific antivenom but not with FFP. Prospective clinical studies are warranted to investigate whether the present findings translate to clinical efficacy., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: Determine the correlation between kaolin-activated thromboelastography (TEG) variables (R, K, angle, and maximum amplitude [MA]) and PCV, fibrinogen concentration (FC), and total fibrinogen (TF) in an ex vivo model., Animals: Two healthy adult mixed-breed dogs., Procedures: Citrated whole blood was obtained and separated into packed red cells, platelet rich plasma, and platelet poor plasma (PPP). An aliquot of PPP was heated to denature heat labile proteins (fibrinogen, factor V, factor VIII). Blood components were recombined for analyses of 6 physiological scenarios: anemia with low fibrinogen; anemia with moderate fibrinogen; anemia with normal fibrinogen; anemia with normal saline; normal PCV and normal fibrinogen; and normal PCV and low fibrinogen. A Kruskal-Wallis test, along with linear regressions on pairwise combinations of TEG variables, was used to determine the correlation between TEG variables and PCV, FC, and TF., Results: Maximum amplitude correlated with FC (R 2 0.60, P < 0.001) and TF (R 2 0.57, P < 0.001) but not PCV (R 2 0.003, P = 0.7). Angle and K time were moderately correlated with FC ([angle: R 2 0.53, P < 0.001]; [K: R 2 0.55, P < 0.001]) and TF ([alpha angle: R 2 0.52, P < 0.001]; [K: R 2 0.51, P < 0.001]) but not PCV. The R time was weakly correlated with PCV (R 2 0.15, P < 0.009) but not FC or TF., Conclusions and Clinical Relevance: In an ex vivo model, plasma proteins but not PCV impacted TEG variables. This suggests that TEG changes noted with anemia are imparted by changes in available fibrinogen in a fixed microenvironment rather than artifact of anemia., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: To evaluate the effects of 7.5% hypertonic saline solution (HSS) on whole blood coagulation in healthy dogs and to compare electrolyte and osmolality measurements between in vivo and in vitro dilution with HSS., Design: Experimental study., Setting: University teaching hospital., Animals: Twelve adult purpose-bred Beagles., Interventions: All 12 dogs received 5 mL/kg 7.5% HSS at 1 mL/kg/min. After a 14-day washout period, 5 of these dogs were randomly selected and received the same volume of 0.9% NaCl. Blood samples were collected before infusion, immediately after infusion, and at 30, 60, and 90 minutes after infusion for the measurement of coagulation using thromboelastography. For comparison of electrolyte concentrations and osmolality between in vitro dilution and in vivo dilution of HSS, 6-mL blood samples were diluted with 7.5% HSS (1:18 ratio) at baseline., Measurements and Main Results: None of the thromboelastography variables differed significantly between the 7.5% HSS group and the 0.9% NaCl group. The sodium and chloride levels, and the osmolality, were significantly increased at all postinfusion time points compared to baseline, while those levels were significantly higher with in vitro dilution than all postinfusion time points. However, almost all the values gradually decreased and became similar to baseline values in case of in vivo dilution., Conclusions: The clinically relevant dose of 7.5% HSS (5 mL/kg) did not affect whole blood coagulation significantly in healthy Beagles. Further studies are necessary to assess the effect of HSS on blood coagulation in canine patients with shock., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: To assess the in vitro effects of crystalloid and colloid IV fluids on the thromboelastographic (TEG) variables of canine whole blood., Design: In vitro experimental study., Setting: Veterinary teaching hospital., Animals: Twenty-two healthy dogs., Intervention: Citrated whole blood samples collected from healthy dogs were diluted with 3.4% hypertonic saline (HTS 3.4), 7% hypertonic saline (HTS 7), and 20% mannitol at 8% and 16% dilutions; hydroxyethyl starch 130/0.4 (HES 130/0.4) at 16% dilution; lactated Ringer's solution (LRS) at 16%, 33%, and 66% dilutions; and HTS 7-HES 130/0.4 at 25% and 50% dilutions. Kaolin-activated TEG analysis was concurrently performed on diluted and control (undiluted) samples., Measurements and Main Results: Dilution of canine whole blood with LRS compared to control reduced α angle and MA at both 33% (P = 0.009 and P = 0.011, respectively) and 66% dilution (P < 0.001 and P < 0.001, respectively), and prolonged K time at 66% dilution (P = 0.003). At 16% dilution, HTS 3.4, prolonged R time (P = 0.007), while mannitol, a fluid iso osmolar to HTS 3.4, prolonged K time (P = 0.006), reduced α angle (P < 0.001), MA (P = 0.046), and LY60 (P = 0.015). At 8% dilution, HTS 7, a fluid of high osmolarity and tonicity, prolonged R time (P = 0.009) and reduced MA (P = 0.015), while all measured TEG variables were altered at the 16% dilution (P < 0.01 for all variables). HES 130/0.4 reduced α angle (P = 0.031) and MA (P = 0.001) and increased LY60 (P < 0.001) at 16% dilution. Comparing different fluid types, HES 130/0.4 and HTS 3.4 had no to minor, mannitol intermediate, and HTS 7 profound effects on TEG variables (P < 0.05) when compared to LRS at the same dilution., Conclusions: In vitro dilution of canine whole blood with commonly used IV fluids leads to thromboelastographic changes consistent with hypocoagulability in a dose dependent manner for all fluid types tested. Viscoelastic changes are also influenced by fluid characteristics, specifically tonicity and osmolarity., (© Veterinary Emergency and Critical Care Society 2020.)

Objective: To examine the extent to which rapid thromboelastography (r-TEG) could decrease the testing time in comparison with that required for kaolin-activated thromboelastography (TEG), and to compare 2 types of blood samples (ie, native and citrated whole blood [WB]), for determining r-TEG values in healthy dogs., Design: Prospective observational study., Setting: University teaching hospital., Animals: Sixteen healthy Beagles., Interventions: Kaolin-activated TEG test using citrated WB samples and r-TEG test using native and citrated WB samples were performed in 16 dogs. At 60 minutes after the initial blood sampling, further samples were collected from a subset of 6 dogs in the same manner to evaluate intraindividual repeatability of r-TEG., Measurements and Main Results: The mean time to maximum amplitude (MA) for r-TEG with native and citrated WB samples was recorded as 1313.9 ± 250.9 seconds and 1351.3 ± 264.6 seconds (mean ± SD), respectively, and 1779.9 ± 197.0 seconds for kaolin-activated TEG. Coefficients of variation with native and citrated WB samples for r-TEG values, TEG-activated clotting time, clot formation time, α angle, and MA, were determined to be 13.4% versus 18.8%, 11.1% versus 16.6%, 4.2% versus 5.1%, and 10.0% versus 10.0%, respectively. Intraindividual variations were lower for native WB samples than for citrated WB samples., Conclusions: The r-TEG test significantly decreased the mean time to MA compared with the kaolin-activated TEG test. In addition, native WB samples showed lower coefficients of variation and intraindividual variation than citrated WB samples in r-TEG analysis; this suggests that native WB samples can provide more consistent results. Therefore, the r-TEG method using native WB samples is recommended for assessment of dogs' hemostatic status when an early diagnosis is required., (© Veterinary Emergency and Critical Care Society 2019.)

Objective: To determine the effect of Yunnan Baiyao (YB) on hemostatic parameters measured by thromboelastography (TEG) in apparently healthy cats administered 1 capsule of YB orally twice daily for 1 week., Design: Prospective study of client-owned cats at a small animal specialty hospital., Setting: One private referral center., Animals: Twenty client-owned adult cats were prospectively enrolled., Interventions: All cats underwent echocardiographic examination by the same board-certified cardiologist to rule out occult cardiomyopathy. Blood samples were collected for analysis of baseline CBC, fibrinogen, and kaolin-activated TEG values. Cats were administered 1 capsule (250 mg/capsule) of YB twice daily orally for 1 week and the physical examination, CBC, fibrinogen, and TEG were re-evaluated. Any side effects attributed to YB were noted at this time., Measurements and Main Results: Three cats were excluded as 2 cats were identified with underlying cardiomyopathy and another cat had a cystic mass in the cranial mediastinum identified via echocardiography. Seventeen cats were treated with YB; however, 1 cat could not complete the study due to severe vomiting associated with YB administration. The remaining 16 cats completed the study, although 2 additional cats experienced transient vomiting. Yunnan Baiyao administration was associated with a significant decrease in HCT and red blood cell count, although no cat became anemic. None of the TEG parameters significantly changed compared to baseline after 1 week of YB therapy., Conclusions: The results of this study suggest YB at a dose of 1 capsule orally twice daily in cats fails to produce any significant change in hemostatic parameters as measured by TEG, although it did significantly reduce HCT and red blood cell count. Yunnan Baiyao was tolerated for most of the cats, although 3 of 17 (17.6%) cats experienced vomiting. Clinicians should be aware of these effects before considering the use of YB in cats., (© Veterinary Emergency and Critical Care Society 2019.)

Objective: To characterize hemostatic profiles in dogs with acute pancreatitis., Design: Prospective and observational study., Setting: Tertiary referral centers., Animals: Fifteen client-owned dogs with acute pancreatitis enrolled between December 1, 2011 and June 1, 2012., Materials and Methods: Blood samples were collected on admission for measurement of platelet count, PCV, thromboelastography (TEG), antithrombin, prothrombin time, activated partial thromboplastin time, D-dimer, von Willebrand factor, and fibrinogen values, which were compared to reference intervals derived from healthy dogs. The Wilcoxon rank-sum test was used to test for differences in continuous variables between study subjects and reference intervals., Measurements and Main Results: Dogs with acute pancreatitis were globally hypercoagulable using TEG when compared with reference intervals. Dogs with acute pancreatitis had significantly higher D-dimers (1,144 μg/L vs 251 μg/L [6264.5 vs 1374.5 nmol/L]; P = 0.001), fibrinogen (837 vs 232 mg/dL [8.37 vs 2.32 g/L]; P < 0.001), and von Willebrand factor (92.9% vs 65.1%; P = 0.02) as well as significantly lower antithrombin (85.7% vs 120%; P < 0.001) and prothrombin time values (3.8 vs 7.6 sec; P < 0.001) than reference intervals., Conclusions: Laboratory evidence of hypercoagulability was present in dogs with acute pancreatitis. TEG may be useful in dogs with acute pancreatitis for monitoring response to therapy and guiding therapeutic interventions., (© Veterinary Emergency and Critical Care Society 2019.)

Objective: To document if a transient hypercoagulable state occurs in healthy dogs following abrupt cessation of unfractionated heparin (UFH) therapy., Design: Prospective experimental pilot study., Setting: University research facility., Animals: Seven adult random-source male dogs., Intervention: Thromboelastography (TEG) and thrombin-antithrombin (TAT) complex formation were used to assess coagulation status in healthy dogs. Seven adult research dogs received 200-300 IU/kg subcutaneous UFH every 8 hours for 4 days. A final IV bolus of 100 IU/kg was given on day 4 and the peak measured heparin concentration 1 hour later is defined as the start of heparin withdrawal (time 0). Citrated whole blood samples were collected at baseline (prior to heparin administration) and 3, 6, 12, 30, and 48 hours after UFH withdrawal. At all time points, a kaolin-activated TEG was performed and citrated plasma for measurement of TAT concentration was collected for batch analysis. Fibrinogen concentration, PCV, total plasma proteins, and platelet count were measured at baseline and 48 hours after heparin withdrawal., Measurements and Main Results: Compared to baseline, TAT was increased 12 hours after heparin withdrawal and returned to baseline by 30 hours. TEG clot formation time (K) was decreased 30 and 48 hours after heparin withdrawal., Conclusion: TAT results suggest that a transient increase in thrombin generation developed 12 hours after withdrawal of UFH therapy. Though clot kinetics were rapid compared to baseline beginning 30 hours after heparin withdrawal, a return to baseline was not documented. Future studies are warranted to determine the clinical relevance of these results and to evaluate the effect of UFH withdrawal in critically ill animals., (© Veterinary Emergency and Critical Care Society 2018.)

Objective: To assess interindividual (CV G ) and intraindividual (CV I ) variability over time for results of thromboelastography (TEG) and whole-blood impedance platelet aggregometry in healthy dogs., Animals: Six healthy Beagle dogs., Measurements and Main Results: Tissue factor (TF)-activated TEG and adenosine diphosphate (ADP) and arachidonic acid (AA)-induced whole blood impedance platelet aggregometry were performed at 3 different time points (days 1, 4, and 6). In addition, platelet count, hematocrit, and plasma fibrinogen concentrations were recorded each study day. Activated partial thromboplastin time, one-stage prothrombin time, antithrombin activity, and D-dimer concentrations were measured on the first day of the study. For TEG, the variables reaction time (R), clotting time (K), rate of clot formation (α), and maximum amplitude (MA) were recorded. For platelet aggregometry, the areas under the curve for ADP (AUC ADP )- and AA (AUC AA )-induced aggregation were measured. The CV I was lower than the CV G over time for MA, AUC ADP , and AUC AA ; however, the CV I was higher than the CV G for the TEG variables R, K, and α. There were no statistical differences in the platelet count, hematocrit, and fibrinogen measurements over time., Conclusions: In healthy dogs, a subject-based reference interval for ADP- and AA-induced platelet aggregometry and the TEG variable MA provide a more sensitive method to detect changes. However, due to the high CV I , population-based reference intervals may be more appropriate for interpretation of the TEG variables R, K, and α., (© Veterinary Emergency and Critical Care Society 2018.)

Objective: To compare lipid emulsion-induced hemolysis in blood from dogs with inflammatory leukograms to blood from healthy dogs, and determine the impact of a prototypical soy-based phospholipid emulsion on coagulation in whole blood from healthy dogs., Design: Ex vivo study using EDTA and citrated whole blood from healthy dogs and EDTA anticoagulated whole blood from dogs with inflammatory leukograms., Setting: University research laboratory., Animals: Healthy dogs (total of 16, 9 for hemolysis assays and 6 for thromboelastography) included student- and staff-owned animals. Blood samples from dogs with inflammatory leukograms (8) were obtained from the clinical pathology laboratory after the complete blood count was performed as part of patient care. For the purposes of this study, an inflammatory leukogram was defined as a neutrophilia with a left-shift (minimum of 3% band neutrophils) and evidence of toxic change., Interventions: None., Measurements and Main Results: Hemolysis was measured via spectrophotometric quantification of released hemoglobin and expressed as a percent of a water-lysed control. The soy emulsion caused hemolysis in blood from healthy dogs, ranging from 3.6% to 16.4% as the dose increased, and 4.1% to 25.0% in blood from dogs with inflammatory leukograms. Hemolysis between these patient groups was significantly different at the highest dose. Coagulation was assessed by native thromboelastography. Treatment of whole blood with the lipid emulsion caused a significant decrease in the time to clot formation (R) and a shorter time to reach a clot amplitude of 20 mm (K)., Conclusions: Soy-based lipid emulsions cause hemolysis that is more severe in blood from dogs with inflammatory leukograms and accelerate clot formation in canine blood. The in vivo significance of these findings is not clear at this time, but warrants additional investigation given the use of these emulsions in clinical practice., (© Veterinary Emergency and Critical Care Society 2018.)

Objective: To establish and compare the repeatability and reproducibility of activated thromboelastography (TEG) and thromboelastometry (ROTEM) assays., Design: Multicenter in vitro test standardization., Setting: Veterinary academic centers., Animals: Test samples were obtained from normal, healthy dogs. Sixty identical 5 mL aliquots of canine platelet-rich plasma collected by apheresis, frozen in 6% dimethyl sulfoxide, were tested initially. Sixty identical 6 mL aliquots of canine fresh frozen plasma with admixed cryoprecipitate were subsequently evaluated., Interventions: None., Measurements and Main Results: Frozen study samples, quality controls, reagents, and consumables were distributed to participating centers (7 TEG and 3 ROTEM). TEG centers analyzed study samples with kaolin and tissue factor activated assays; ROTEM centers ran proprietary ellagic acid activated and tissue factor activated assays. All machines underwent quality control prior to sample analysis. Within- and between-center coefficients of variation (CVs) were calculated and compared using Mann-Whitney tests and calculation of intraclass correlation coefficients. Within and between centers, individual parameters for both TEG and ROTEM assays were comparable. Both within-center and between-center CVs varied markedly (0.7-120.5% and 1.4-116.5%, respectively) with assay type, instrument, and parameter. CVs for equivalent parameters were not significantly different between the 2 platforms. Intraclass correlation coefficients suggested moderate agreement between centers. In general, individual parameter CVs for platelet-rich plasma samples were lower in TEG centers, while CVs for canine fresh frozen plasma with admixed cryoprecipitate samples were lower in ROTEM centers., Conclusions: More variation within and between centers was identified than anticipated, but some parameters such as alpha angle were repeatable and reproducible. Sample types for future multicenter standardization efforts will require further optimization and may need to be adapted separately to each platform. Individual centers using viscoelastic tests for evaluation and management of clinical patients should take steps to minimize preanalytical and analytical sources of variation., (© Veterinary Emergency and Critical Care Society 2018.)

Objective: To determine the effect of Yunnan Baiyao (YB) on hemostatic parameters measured by thromboelastography (TEG) in healthy dogs administered 1 capsule of YB orally twice daily for 1 week., Design: Prospective study of client-owned dogs at a small animal specialty hospital., Setting: Private referral center., Animals: Eighteen client-owned adult dogs weighing at least 15 kg., Interventions: Dogs had a baseline TEG performed and then each dog was administered 1 capsule of YB twice daily by mouth for 1 week and the TEG was reevaluated. Any side effects attributed to YB were noted at this time., Measurements and Main Results: All 18 enrolled dogs completed the study. Dogs that received 1 capsule (250 mg/capsule) of YB orally twice daily had significantly increased G as well as A30 and A60 values. There was also a significantly decreased LY30 and LY60 values after 1 week. The YB appeared well tolerated as only one dog developed mild diarrhea., Conclusions: The results of this study suggest that YB at 1 capsule orally twice daily in healthy medium to large breed dogs increases the strength of the clot as measured by TEG and that YB was apparently well tolerated in the study population reported here. Larger prospective studies in different disease states are warranted to further evaluate these preliminary findings., (© Veterinary Emergency and Critical Care Society 2018.)

Objective: To investigate parameters causing canine thromboelastographic hypercoagulability and to investigate whether thromboelastography (TEG) with Cytochalasin D (Cyt D) added is related to parameters of platelet activity., Design: Prospective observational study on hemostatic and inflammatory parameters. Data were collected between November 2012 and July 2013., Setting: University teaching hospital., Animals: Twenty-eight dogs suffering from diseases predisposing to thrombosis and 19 clinically healthy dogs. Diseased dogs were enrolled if they fulfilled inclusion criteria regarding age, size, informed client consent, and obtained a diagnosis of a disease that has been associated with thrombosis or hypercoagulability., Interventions: None., Measurements and Main Results: Parameters of coagulation and anticoagulation, fibrinolysis, and antifibrinolysis, platelet activity, inflammation, platelet count, and hematocrit were measured using CBC, TEG, platelet aggregation on multiplate, platelet activity on flow cytometry, and hemostatic and inflammatory markers on plasma and serum analyses. ANOVA and multilinear regression analyses indicated that especially hematocrit and the inflammatory parameters C-reactive protein and interleukin-8 showed best association with overall clot strength in diseased dogs with hypercoagulable TEG tracings. Ratios presumed to reflect platelet contribution to the TEG tracing obtained in TEG analyses with Cyt D were related especially with hematocrit and P-selectin expression of platelets measured after γ-Thrombin activation on flow cytometry., Conclusion: Overall clot strength in TEG analyses of the hypercoagulable dogs included in the present study appears to be primarily associated with inflammation as well as hematocrit. Furthermore, the ratio between standard TEG analyses and TEG analyses with Cyt D may reflect some degree of platelet activity., (© Veterinary Emergency and Critical Care Society 2017.)

Objective: To determine the extent of intraoperator (between duplicate samples) and interoperator (between different operators) variability in equine thromboelastography (TEG)., Design: Kaolin-activated TEG was performed in duplicate by operator-pair A/B or A/C (2 groups of 10 horses) using discrete setups, within 30-45 minutes of vacuum-assisted blood collection. Recorded TEG variables included clot initiation time (R), clot formation time (K), rate of clot formation (α), clot strength (MA), and viscoelastic/shear strength (G). Operators independently determined the clinical coagulation status for each sample. Intra- and interoperator variabilities were reported as coefficients of variation (CV), using descriptive statistics and paired samples t-test or Wilcoxon matched pair signed-rank test (P < 0.05 considered significant)., Animals: Twenty hospitalized adult horses with no clinical evidence of systemic inflammation., Measurements and Main Results: Mean intraoperator CVs ranged from 2.6 to 14% (operator A), 2.8 to 13% (operator B) and 1.2 to 18% (operator C). Both intra- and interoperator variabilities were lowest for MA (1.2-3.2%) and G (2.9-7.3%), and highest for K (13-23%). Mean CVs for all TEG parameters were lower when comparing intra- to interoperator variation. Seventy percent of horses had at least 1 TEG variable (out of 4 replicates) outside the established reference intervals. Assessment of coagulation status was conserved between operators in 9/10 and 8/10 horses for A/B and A/C, respectively, with comparable agreement between operator A/B (к = 0.73) and A/C (к = 0.74)., Conclusions: TEG measurements of MA and G are more reproducible than assessment of K, within samples and between operators. The highest test variability was thus observed within the early phase of clot formation., (© Veterinary Emergency and Critical Care Society 2017.)

Objective: To establish reference intervals for rotational thromboelastometry (ROTEM) using feline blood., Design: Prospective study., Setting: University teaching hospital., Animals: Twenty-three clinically healthy cats between 1 and 15 years., Intervention: For each cat, whole blood was collected via jugular or medial saphenous venipuncture, and blood was placed into a serum tube, a tube containing potassium-EDTA, and tubes containing 3.2% sodium citrate. The tubes were maintained at 37°C for a maximum of 30 minutes before coagulation testing., Measurements and Main Results: ROTEM tests included the EXTEM, INTEM, FIBTEM, and APTEM assays. In addition, prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen concentration (Clauss method) were analyzed for each cat. Reference intervals for ROTEM were calculated using the 2.5-97.5 th percentile for each parameter, and correlation with the standard coagulation profile was performed. Compared to people, clinically healthy cats had similar values for the EXTEM and INTEM assays, but had lower plasma fibrinogen concentrations (0.9-2.2 g/L), resulting in weaker maximum clot firmness (MCF, 3-10 mm) in the FIBTEM test. In 18 cats, maximum lysis (ML) values in the APTEM test were higher than in the EXTEM test, which seems unlikely to have occurred in the presence of aprotinin. It is possible that the observed high maximum lysis values were due to clot retraction rather than true clot lysis. Further studies will be required to test this hypothesis., Conclusions: Cats have a weaker clot in the FIBTEM test, but have a similar clot strength to human blood in the other ROTEM assays, which may be due to a stronger contribution of platelets compared to that found in people. In cats, careful interpretation of the results to diagnose hyperfibrinolysis is advised, especially with the APTEM test, until further data are available., (© Veterinary Emergency and Critical Care Society 2017.)

Objective: To evaluate the effects of a 6% hydroxyethyl starch (130/0.42) solution in either a buffered, electrolyte-balanced (HES-BAL), or a saline (HES-SAL) carrier solution on canine platelet function and whole blood coagulation., Design: Prospective, randomized study., Setting: University teaching hospital., Animals: Thirty-seven client-owned dogs undergoing general anesthesia for arthroscopy or imaging studies., Interventions: Dogs received a 15 mL/kg intravenous bolus of HES-SAL (n = 13), HES-BAL (n = 14), or a modified Ringer's solution (n = 10) over 30-40 minutes. Coagulation was analyzed using a Platelet Function Analyzer-100 (closure time [Ct PFA ]), and whole blood thromboelastometry (ROTEM) with extrinsically (ex-tem and fib-tem) and intrinsically (in-tem) activated assays, which assessed clotting time (CT), clot formation time (CFT), maximal clot firmness (MCF), and lysis index (LI). Coagulation samples were assayed prior to fluid administration (T0), and 5 minutes (T1), and 3 hours (T2) following fluid bolus administration, respectively., Results: Both HES solutions resulted in impaired platelet function as indicated by a significant prolongation of Ct PFA at T1 as compared to T0, but which resolved by T2. An IV bolus of Ringer's solution did not alter platelet function. In both HES groups, whole blood coagulation was significantly impaired at T1 as indicated by a significant increase in in-tem CFT, and a significant decrease in ex-tem, in-tem, and fib-tem MCF compared to T0. Furthermore, a significant increase in ex-tem CFT at T1 compared to T0 was found in the HES-SAL group. With the exception of in-tem MCF after HES-BAL, these effects were not present at T2. No significant differences were found in Ct PFA or any ROTEM variable at any time point between HES-SAL and HES-BAL., Conclusion: Administration of a single bolus of 15 mL/kg 6% HES 130/0.42 results in significant but short-lived impairment of canine platelet function and whole blood coagulation, regardless of carrier solution., (© Veterinary Emergency and Critical Care Society 2016.)

Background: Evaluation of underlying hemostatic function is challenging when feline patients are receiving an anticoagulant medication. Discontinuing the anticoagulant to obtain accurate results for hemostatic testing may lead to thrombotic complications. The addition of heparinase to blood samples may mitigate the effects of exogenous heparin and allow hemostatic testing., Methods: Tissue factor (TF)-activated thromboelastography (TEG) was performed using citrated whole blood from 19 cats. Assays were performed using citrated whole blood, with and without addition of unfractionated heparin to a concentration of 0.2 U/mL. For each blood sample, TEG assays were performed using a standard cup and a heparinase-coated cup., Key Findings: For TEG variables R, k, α-angle, and MA, mean values were not statistically different when citrated blood was used with standard or heparinase-coated cups. Heparinized blood assayed in standard cups displayed a significantly increased R and k, and significantly decreased α-angle and MA when compared to heparinized blood assayed in heparinase-coated cups. TEG variables for heparinized blood assayed in heparinase cups was not statistically different from those of the citrated whole blood without added heparin., Significance: Heparinase modified, TF-activated, TEG reverses heparin effects in feline-citrated blood., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To evaluate the presence of acute traumatic coagulopathy (ATC) in dogs and cats following blunt trauma and to relate coagulation variables with injury severity and admission variables., Design: Prospective, single center, observational study from 2013 to 2014., Setting: Urban private referral hospital., Animals: Eighteen and 19 client-owned dogs and cats, respectively, sustaining blunt trauma within 8 hours of presentation without prior resuscitation; 17 healthy staff and client-owned control cats METHODS: Blood samples were collected upon presentation for measurement of blood gas, lactate, blood glucose, ionized calcium, PCV, total plasma protein, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, platelet count, and thromboelastography., Results: ATC was diagnosed in 1 dog and 1 cat on presentation. Hypercoagulability was documented in 4/18 (22%) of dogs and 1/19 (5.3%) of cats. In dogs, prolongation of PT (P = 0.018), aPTT (P = 0.013) and decrease in maximum amplitude (MA) (P = 0.027) were significantly associated with injury severity as measured by the animal trauma triage (ATT) score. In cats, PT, aPTT, MA, and clot strength (G) were not associated with injury severity. In cats, increasing blood glucose and lactate were significantly associated with decreasing MA (P = 0.041, P = 0.031) and G (P = 0.014, P = 0.03). In both dogs (P = 0.002) and cats (P = 0.007), fibrinogen concentration was significantly correlated with G., Conclusions: ATC is rare in minimally injured dogs and cats following blunt trauma. In dogs, ATT score is significantly associated with PT, aPTT, and MA, suggesting an increased risk of ATC in more severely injured animals. ATT score does not appear to predict coagulopathies in cats. Future studies including more severely injured animals are warranted to better characterize coagulation changes associated with blunt trauma., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To assess primary and secondary hemostasis following in vitro dilution of canine whole blood (WB) with hydroxyethyl starch (HES) 130/0.4 and HES 670/0.75., Design: In vitro experimental study., Setting: Private practice, teaching hospital., Animals: Twenty-five healthy dogs., Interventions: Each dog underwent venipuncture and 18 mL of venous blood was sampled once., Measurements and Main Results: Collected blood was separated in 4 aliquots. Aliquot A served as baseline sample. The remaining tubes of WB were diluted with 0.9% saline, HES 670/0.75 and HES 130/0.4 at a ratio of 1:5.5. Dilutional effects were evaluated using prothrombin time (PT), activated partial thromboplastin time (aPTT), packed cell volume (PCV), thromboelastography (TEG), and platelet closure time (Ct), which was measured using a platelet function analyzer (PFA). Clot strength (ie, G value) was calculated from measured TEG values. Significant increases in PT (P < 0.05) and aPTT (P < 0.05) were documented following WB dilution with saline. Dilution of WB with HES 670/0.75 and HES 130/0.4 resulted in significant hypocoagulable changes in K, MA and G (P < 0.05) compared to baseline and saline. When comparing saline to HES 670/0.75, both R and K values were significantly increased (P < 0.05). K value was significantly increased (P < 0.05) when comparing baseline to HES 130/0.4 and HES 670/0.75. Ct (P < 0.05) was significantly prolonged after WB dilution with HES solutions but not after saline., Conclusions: Dilution of WB with HES 670/0.75 and HES 130/0.4 resulted in changes in primary and secondary hemostasis. Although there were small differences between saline and HES 670/0.75, no differences between HES solutions were evident in this small study. This may suggest there would be minimal increases in bleeding risk when either solution is administered to dogs at low doses. Clinical relevance of our findings requires further investigation., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To characterize the correlation between thromboelastography (TEG) variables using strong activators and anti-Xa (AXa) activity in healthy dogs administered subcutaneous unfractionated heparin (UFH)., Design: Prospective experimental study., Setting: University research facility., Animals: Eight adult random-source male dogs., Intervention: Dogs were randomized to receive subcutaneous UFH at 200, 250, or 300 IU/kg every 8 hours for a total of 10 injections. Blood samples were collected at time 0 (preheparin) and 3, 6, and 8 hours after the 1st (Day 1) and 10th (Day 4) UFH injection.  After the 8-hour blood sample was obtained on day 4, a 100 IU/kg IV bolus of UFH was administered and an additional blood sample was collected 1 hour later (hour 9). AXa activity, activated partial thromboplastin time (aPTT), and TEG (with up to 5 activators) were performed at each time point.  Modes of activation for TEG included  recalcified (Ca), Ca with heparinase (CaH), CaH and tissue factor 1:3600 (CTF3600H), Ca with tissue factor 1:100 (CTF100), and RapidTEG. Spearman rank correlations were calculated for each of the aforementioned parameters and the AXa activity. P-values were corrected for multiple comparisons with a Bonferroni correction., Measurements and Main Results: Significant correlations were found between AXa activity and the TEG R values generated with CTF100 (R = 0.83, P ≤ 0.0001) and RapidTEG (R = 0.90, P < 0.0001), as well as both forms of aPTT measurement (R = 0.86 and 0.84, P < 0.0001)., Conclusions: This study demonstrates that TEG variables derived using robust activation correlate with AXa activity as well as aPTT and have the potential to be used for monitoring UFH therapy in healthy dogs.  Future studies are warranted to evaluate its diagnostic utility in critically ill animals., (© Veterinary Emergency and Critical Care Society 2016.)

Objectives: To assess the measurement reliability of rotational thromboelastometry (ROTEM) measurements in horses, establish reference intervals for healthy horses, and evaluate the relationship between ROTEM variables, hematologic variables, and standard coagulation tests., Design: Prospective observational study., Setting: University teaching hospital., Animals: Fifty healthy and 10 diseased adult horses., Interventions: None., Measurements and Main Results: Blood was sampled from 10 healthy and 10 diseased horses and samples were repeatedly analyzed to evaluate measurement reliability of various ROTEM variables. Four different ROTEM assays (ie, EXTEM, INTEM, FIBTEM, and APTEM) were run simultaneously under standardized conditions. The device-related, operator-related, and day-to-day variability for the majority of ROTEM variables was very low to low, as indicated by a coefficient of variation (CV) of < 15%. Most of test-retest variability of ROTEM variables appeared to be device-related. Blood samples from 50 clinically healthy horses were used to establish reference intervals for ROTEM variables. Multiple stepwise regression analyses identified associations of different ROTEM variables with hematocrit, total protein concentration, fibrinogen concentration, platelet count, prothrombin time, activated partial thromboplastin time, and thrombin time., Conclusions: ROTEM is a feasible method to evaluate coagulation in horses. Its measurement reliability is acceptable, but device-related measurement variability has to be considered. Reference intervals are presented, but the influence of hematocrit, platelet count, and fibrinogen concentration may need to be taken into account when interpreting individual test results., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To determine whether the overall hemostasis potential (OHP) and calibrated automated thrombogram (CAT) were significantly different between dogs with thrombosis and normal dogs., Animals: Ten dogs with clinical evidence of thromboembolic disease had both OHP and CAT performed. Forty healthy control dogs had OHP performed, and 23 of these also had CAT performed., Measurements and Main Results: Dogs with thrombosis had significantly higher OHP (P = 0.003), overall coagulation potential (P = 0.0001), and maximum optical density (Max OD, P < 0.0001) than normal dogs, and a significantly longer delay in the start of clot formation (P = 0.01). Max OD was higher than established reference intervals in 80% of the dogs with thrombosis. Using the CAT assay, dogs with thrombosis had a significantly longer lag time than normal dogs (P < 0.001). Plasma fibrinogen concentration correlated positively with overall coagulation potential, OHP, Max OD, and the slope of the OHP curve (P < 0.05), and was increased in 90% of dogs with thrombosis., Conclusions: The OHP assay findings were significantly different between normal dogs and those with thrombosis. CAT did not detect any significant differences between these populations of dogs, other than the lag time of the assay., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To evaluate the relationship between shortened prothrombin time (PT) or activated partial thromboplastin time (aPTT) values, clinical findings associated with hypercoagulability, suspicion of pulmonary thromboembolism (PTE), D-dimer concentrations, and thromboelastogram (TEG) indices., Design: Retrospective observational study from 2006 to 2011., Setting: University veterinary teaching hospital., Animals: Twenty-three dogs with TEG tracings and shortened PT or aPTT values and 23 control dogs with TEG tracings and normal PT and aPTT values., Measurements and Main Results: Parameters evaluated included signalment, coagulation testing results (PT, aPTT, D-dimer concentration), TEG measurements (R, K, α, maximal amplitude) and calculated clotting index, findings of clinical hypercoagulability (thrombosis of intravenous/intra-arterial catheters, vessel thrombosis, and suspected PTE). Dogs with shortened PT or aPTT had significantly more thrombus formation (P = 0.038), suspicion of PTE (P < 0.001), and increased D-dimer concentration (P < 0.001) compared to dogs with normal PT and aPTT values. There were no significant findings when compared to TEG values., Conclusions: A shortened PT or aPTT in dogs may be indicative of a hypercoagulable state as evidenced by an increased incidence of thrombosis, frequency of suspected PTE, and increased circulating D-dimers. A prospective study is warranted to further evaluate the use of PT and aPTT to diagnose hypercoagulable states., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To determine whether there is an association between thromboelastography (TEG) data and necropsy evidence of thrombosis in a cohort of critically ill dogs., Design: Retrospective study (2005-2010)., Setting: University teaching hospital., Animals: Thirty-nine client-owned critically ill dogs for which TEG was performed within 7 days of complete necropsy., Interventions: None., Measurements and Main Results: Thrombi were found in 26 (67%) dogs. Spayed females (n = 20) were significantly more likely to have thrombosis (P = 0.0127). No significant association was found between presence of thrombosis and any TEG parameter, the calculated coagulation index, results of coagulation testing, type of vascular access, or clinical diagnosis. D-dimers were significantly higher in dogs with thrombosis (P = 0.0207) and a weak positive correlation was found between D-dimer value and number of sites of thrombosis (ρ = 0.18, P = 0.0045). Dogs with WBC > 16 × 10(3) /μL were more likely to have thrombosis compared to others (odds ratio 5.56, 95% confidence interval 1.2-25.7, P = 0.025)., Conclusions: This study found no association between any TEG parameter and the presence of thrombosis on postmortem examination., (© Veterinary Emergency and Critical Care Society 2016.)

Objective: To evaluate hemostatic changes following experimental acute hemorrhage in dogs using traditional coagulation tests (eg, platelet count, prothrombin time [PT], and activated partial thromboplastin time [aPTT]), kaolin-activated thromboelastography (TEG), and whole blood multiple electrode impedance platelet aggregometry., Design: Prospective study., Setting: Research laboratory., Animals: Five Beagles., Interventions: Dogs were anesthetized prior to obtaining blood samples for baseline PCV, total plasma protein (TPP), arterial blood-gas, platelet count, PT, aPTT, TEG, fibrinogen, and aggregometry. Blood was obtained at 4 additional time points, following 20% blood volume loss, 40% blood volume loss, 60 minutes of sustained hypotension, and after autologous blood transfusion. In addition, heart rate and direct arterial blood pressure were measured at each time point., Measurements and Main Results: Significant decreases were noted for PCV (P = 0.048), TPP (P < 0.0001), and arterial blood pressures (P < 0.0001) over time. Platelet count did not change significantly (P = 0.879), but platelet function was decreased following hemorrhage when arachidonic acid (P = 0.004) and ADP (P = 0.008) were used as agonists. The TEG variables R (P = 0.030), MA (P = 0.043), and G (P = 0.037) were significantly, albeit mildly, changed following hemorrhage. Significant prolongations in PT (P < 0.0001) and aPTT (P = 0.041), and decreases in fibrinogen concentration (P = 0.002) were also seen., Conclusion: Platelet dysfunction occurred following hemorrhage in this model, despite a stable platelet count. Additionally, significant changes associated with hemorrhage were documented in aPTT, fibrinogen, and MA. Platelet function testing in dogs with naturally occurring hemorrhage warrants further investigation., (© Veterinary Emergency and Critical Care Society 2016.)

Background: Hypercoagulability is a well-known feature of canine immune-mediated hemolytic anemia (IMHA) and is believed to increase the risk of thrombosis. This study was undertaken to differentiate the relative contribution of platelets and clotting proteases to this hypercoagulability using thromboelastography (TEG)., Study Design: Retrospective observational study., Methods: Thromboelastograms from 27 dogs with IMHA were retrospectively evaluated. Standard TEG parameters (R, K, α, MA), the G value, and the novel parameter delta (Δ) were determined. Hypercoagulability was attributed to the platelet component of hemostasis when there was an increased G value with a normal Δ value., Key Findings: Nineteen of 27 dogs (70.4%) had ≥ 2 TEG variables suggestive of hypercoagulability, 18 (66.7%) had a hypercoagulable G value, and 11 (40.7%) had a hypercoagulable Δ value. Ten of 27 (37%) samples met the criteria for platelet hypercoagulability., Significance: Our report documents the derivation and application of the Δ value to differentiate enzymatic from platelet hypercoagulability. Further studies are required to validate the use of these TEG variables in this manner. The hypercoagulable tendency in dogs with IMHA is complex and multifactorial, and in some dogs this hypercoagulability may be attributed primarily to platelet hyper reactivity. Our findings may support the use of anti-platelet drugs in some dogs with IMHA., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To investigate the effects of in vitro hemodilution with lactated Ringers solution (LRS), hetastarch (HES), and fresh frozen plasma (FFP) on whole blood coagulation in dogs as assessed by kaolin-activated thromboelastography., Design: In vitro experimental study., Setting: University teaching hospital., Animals: Six healthy client-owned dogs., Interventions: Whole blood was collected and diluted in vitro at a 33% and 67% dilution with either LRS, HES, or FFP., Measurements and Main Results: Kaolin-activated thromboelastography was performed on each sample as well as a control. Thromboelastographic parameters R (min), alpha (deg), K (min), and MA (mm) were measured and compared to the sample control for each dilution using mixed model methodology. Prolongation in coagulation times were seen at both dilutions with LRS and HES. There was no significant difference in R times at the 33% dilution, but R time was significantly prolonged at the 67% dilution with HES (P = 0.004). MA was significantly decreased for LRS at both dilutions (P = 0.013, P < 0.001) and more profoundly decreased for HES (P < 0.001, P = 0.006). No significant difference in any parameter was found for FFP., Conclusions: In vitro hemodilution of whole blood with both LRS and HES but not FFP resulted in significant effects on coagulation with HES having a more profound effect. In vivo evaluation of changes in coagulation with various resuscitation fluids is warranted and may be clinically relevant., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To assess the utility of population-based reference intervals (PRIs) for interpreting thromboelastography (TEG) variables in horses using biological variation data., Design: Prospective cohort biologic variation study conducted over a 5-week period., Setting: Veterinary teaching hospital and research facility., Animals: Ten clinically healthy horses randomly selected from a veterinary school research and teaching herd., Interventions: Horse health was determined using physical examination, CBC, and biochemical and coagulation profiles prior to the start of the study. Subsequently, once weekly blood sampling for TEG testing was performed for 5 weeks., Measurements and Main Results: The 4 TEG variables reaction time (R), clot formation time (K), angle, and maximum amplitude (MA) were measured, and coefficient of variation representing within- and between-horse biological variation (CVi and CVg , respectively) and coefficient of variation representing analytical variation (CVa ) were calculated using a nested ANOVA after removing outlier data. The CVi , CVg , and CVa for R were 26.8%, 5.2%, and 5.9%; for K were 31.0%, 0.0%, and 5.9%; for angle were 9.4%, 6.2%, and 21.7%; and for MA were 3.4%, 4.1%, and 4.4%, respectively. Index of individuality (IOI) was then calculated for each variable using the formula {( CVi² + CVa²/CVg²)}¹/². IOI for R was 5.3, for angle was 3.8, and for MA was 1.4; IOI was not assessed for K., Conclusions: PRIs are appropriate for TEG variables, R, angle, and MA when interpreting results from individual horses based on calculated IOI values equal to or greater than 1.4. PRIs are likely appropriate when interpreting K, but IOI could not be calculated for this variable., (©Veterinary Emergency and Critical Care Society 2015.)

Objective: To relate coagulation and fibrinolysis derangements to shock severity as reflected by plasma lactate concentrations in dogs with spontaneous hemoperitoneum (SHP) and determine the impact on transfusions., Design: Prospective, observational, case-control study., Setting: Three veterinary teaching hospitals., Animals: Twenty-eight client-owned dogs with SHP and 28 breed- and age-matched control dogs., Interventions: None., Measurements and Main Results: Blood samples for platelet counts, coagulation, and anticoagulant assays (prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, and protein C, thromboelastography [TEG]), fibrinolysis testing (d-dimer and TEG lysis parameters with and without the addition of 50 U/mL of tissue plasminogen activator [TEG LY30 measured with the addition of 50 U/mL of tPA to the blood sample, LY3050 and TEG LY60 measured with the addition of 50 U/mL of tPA to the blood sample, LY6050 ; LY30 and LY60]), and plasma lactate as an indicator of severity of shock were collected from SHP dogs at the time of diagnosis. SHP dogs were hypocoagulable (prolonged prothrombin time and activated partial thromboplastin time, decreased TEG maximum amplitude) and hyperfibrinolytic (increased LY3050 and TEG LY6050 ) compared to controls. The severity of hypocoagulability was related to protein C activity, while the severity of hyperfibrinolysis was related to plasma lactate concentration. Among the 18 dogs discharged from the hospital, LY3050 was significantly associated with the dose of fresh frozen plasma administered, but none of the parameters were associated with the dose of red blood cells administered., Conclusions: Dogs with SHP have evidence of hypocoagulability, protein C deficiency, and hyperfibrinolysis. Parameters of hyperfibrinolysis were related to plasma lactate concentrations and volume of plasma transfused during hospitalization. These derangements resemble those found in people with acute coagulopathy of trauma and shock, and activation of protein C may be a common feature to both syndromes., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To assess the effects of tranexamic acid (TA) on hematological, hemostatic, and thromboelastographic analytes in healthy adult dogs., Design: Prospective study., Setting: University teaching hospital., Animals: Eleven healthy, staff-owned, adult dogs., Measurements and Main Results: Dogs were administered TA as an IV bolus, followed by a 3-hour constant rate infusion (CRI). Complete blood count, prothrombin time, activated partial thromboplastin time, D-dimer, antithrombin, fibrinogen, and thromboelastography (TEG) were measured prior to, and immediately after TA administration. Vomiting occurred transiently in the first 2 treated dogs, immediately after 20 and 15 mg/kg IV boluses, but not during the CRI. In all other dogs the TA IV bolus dose was reduced to 10 mg/kg, and administered slower, and vomiting did not occur. All measured hemostatic and hematological analytes remained within their reference intervals, however, following TA treatment, significant decreases were recorded in prothrombin time, TEG R and A30 values, Hct, and hemoglobin concentration, while the TEG LY30 significantly increased., Conclusions: Administration of TA as a slow IV bolus at 10 mg/kg, followed by a 10 mg/kg/h CRI over 3 hours to healthy dogs is safe; however, its effect on TEG A30, A60, LY30, and LY60 values was inconsistent with its expected anti-fibrinolytic properties., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: Evaluation of hemostasis using thromboelastometry in dogs with leishmaniasis before and after treatment., Design: Longitudinal observational study., Setting: University veterinary teaching hospital., Animals: Eighty-four adult, client-owned dogs., Measurements and Main Results: Whole blood samples for the coagulation profile were collected from symptomatic dogs with leishmaniasis (group S), asymptomatic dogs with leishmaniasis after treatment (group T), and a control group of healthy dogs (group H). Hemostasis was evaluated by means of standard coagulation profile (prothrombin time, activated partial thromboplastin time, and fibrinogen) and by thromboelastometry (ROTEM). Prothrombin time and activated partial thromboplastin time were within the upper reference range in all 3 groups. Comparison of the ROTEM variables between the 3 groups showed statistically significant differences between group S versus groups T and H, but remaining within the reference ranges. Statistically significant differences in hematocrit and fibrinogen concentrations were noted between groups (group S vs. H: hematocrit P = 0.001, fibrinogen P = 0.002; Group S vs. T: hematocrit P = 0.001, fibrinogen P = 0.001). These variations have interfered with some parameters of the ROTEM profile., Conclusions: This study showed normal standard coagulation profiles in all 3 groups evaluated. The ROTEM results did not fall outside of the maximum values of the reference ranges., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To compare the in vitro effects of hypertonic solutions and colloids to saline on coagulation in dogs., Design: In vitro experimental study., Setting: Veterinary teaching hospital., Animals: Twenty-one adult dogs., Interventions: Blood samples were diluted with saline, 7.2% hypertonic saline solution with 6% hydroxyethylstarch with an average molecular weight of 200 kDa and a molar substitution of 0.4 (HH), 7.2% hypertonic saline (HTS), hydroxyethyl starch (HES) 130/0.4 or hydroxyethyl starch 600/0.75 at ratios of 1:22 and 1:9, and with saline and HES at a ratio of 1:3., Measurements and Main Results: Whole blood coagulation was analyzed using rotational thromboelastometry (extrinsic thromboelastometry-cloting time (ExTEM-CT), maximal clot firmness (MCF) and clot formation time (CFT) and fibrinogen function TEM-CT (FibTEM-CT) and MCF) and platelet function was analyzed using a platelet function analyzer (closure time, CTPFA ). All parameters measured were impaired by saline dilution. The CTPFA was prolonged by 7.2% hypertonic saline solution with 6% hydroxyethylstarch with an average molecular weight of 200 kDa and a molar substitution of 0.4 (HH) and HTS but not by HES solutions. At clinical dilutions equivalent to those generally administered for shock (saline 1:3, HES 1:9, and hypertonic solutions 1:22), CTPFA was more prolonged by HH and HTS than other solutions but more by saline than HES. No difference was found between the HES solutions or the hypertonic solutions. ExTEM-CFT and MCF were impaired by HH and HTS but only mildly by HES solutions. At clinically relevant dilutions, no difference was found in ExTEM-CFT between HTS and saline or in ExTEM-MCF between HH and saline. No consistent difference was found between the 2 HES solutions but HH impaired ExTEM-CFT and MCF more than HTS. At high dilutions, FibTEM-CT and -MCF and ExTEM-CT were impaired by HES., Conclusions: Hypertonic solutions affect platelet function and whole blood coagulation to a greater extent than saline and HES. At clinically relevant dilutions, only CTPFA was markedly more affected by hypertonic solutions than by saline. At high dilutions, HES significantly affects coagulation but to no greater extent than saline at clinically relevant dilutions., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To characterize hemostasis and determine if disseminated intravascular coagulation (DIC) is present in cats with cytauxzoonosis., Design: Cross-sectional study., Setting: University teaching hospital., Animals: Five client-owned cats with cytologic and PCR-confirmed cytauxzoonosis., Interventions: None., Measurements and Main Results: Admission samples were collected for hemostasis testing including platelet count, activated partial thromboplastin time, prothrombin time, fibrinogen, antithrombin (AT), d-dimer, protein C, plasminogen, antiplasmin, factors VII, VIII, IX, X, and XI, von Willebrand factor, and thromboelastography. Results were compiled for combined criteria used to define DIC, and all 5 cats satisfied criteria using a previously described modified scoring system for DIC in cats. The abnormalities found in all 5 cats included thrombocytopenia, low protein C activity, and prolonged prothrombin time; however, none of the cats had low AT activity. None of the cats had clinical signs of hemorrhage despite thrombocytopenia, coagulation factor deficiency (5/5 cats), and thromboelastographic evidence of hypocoagulability (2/5 cats). Three of 5 cats survived to hospital discharge. The nonsurvivors had disseminated cytauxzoonosis with schizont-laden macrophages in vessels of various organs., Conclusions: This is the first report that comprehensively describes the hemostastic status of cats with naturally occurring infection with Cytauxzoon felis. All 5 cats had laboratory evidence of overt DIC. Unlike human and canine models of sepsis-induced DIC, AT deficiency was not found in this series of cats. Further research is warranted to investigate therapeutic strategies targeting thrombotic DIC to improve survival in cats with cytauxzoonosis., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To compare the effects of dipyrone, meloxicam, and of the combination of these drugs on hemostasis in dogs., Design: Prospective, blinded, randomized crossover study., Setting: Research laboratory at a veterinary teaching hospital., Animals: Six adult dogs., Interventions: Animals received 4 intravenous treatments with 15-day washout intervals: control (physiological saline, 0.1 mL/kg), meloxicam (0.2 mg/kg), dipyrone (25 mg/kg), and dipyrone-meloxicam (25 and 0.2 mg/kg, respectively). A jugular catheter was placed for drug injection and for collecting samples for whole blood platelet aggregation (WBPA) and thromboelastometry assays at baseline, 1, 2, 3, 5, and 8 hours after treatment administration. The percent change from baseline of lag time and of the area under the curve (AUC) of impedance changes in response to collagen-induced platelet activation were recorded during WBPA. Thromboelastometry-derived parameters included clotting time, clot formation time, alpha-angle, and maximum clot firmness. The buccal mucosal bleeding time was evaluated by a blinded observer at baseline, 1, 3, and 5 hours after treatment injection., Measurements and Main Results: No significant changes in WBPA and thromboelastometry were recorded in the control treatment. Dipyrone significantly (P < 0.05) increased the lag time for 2 hours and decreased the AUC for 3 hours after injection. Meloxicam did not alter WBPA. Dipyrone-meloxicam significantly increased lag time for 2 hours and decreased the AUC for 5 hours after treatment injection. Experimental treatments did not differ from the control treatment for thromboelastometry and buccal mucosal bleeding time., Conclusions: While meloxicam does not alter hemostasis by the methods evaluated, dipyrone inhibits platelet aggregation for up to 3 hours. Meloxicam-dipyrone combination causes more prolonged inhibition of platelet function than dipyrone alone. Decreased platelet aggregation induced by dipyrone and dipyrone-meloxicam does not appear to impact the viscoelastic properties of the blood clot nor increase the risk of bleeding in dogs without preexisting hemostatic disorders., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To evaluate blood coagulation using thromboelastometry in dogs following orthopedic surgery., Design: Longitudinal observational study., Setting: University veterinary teaching hospital., Animals: Thirty-four adult client-owned dogs., Measurements and Main Results: Dogs undergoing elective or emergency orthopedic surgery had whole blood collected before (T0), at 24 hours (T1), and 1 week (T2) after surgery. Whole blood from each dog was collected by jugular venipuncture using a 20-Ga needle and minimum venous stasis. The blood was placed into tubes containing 3.8% trisodium citrate (1 part citrate: 9 parts blood) and rested at 37°C. Coagulation was evaluated by means of thromboelastometry using the in-TEM, ex-TEM, and fib-TEM assays. Statistically significant increases (P < 0.05) in maximum clot firmness (MCF) from T0 to T1 in the in-TEM and fib-TEM profiles (both P = 0.0001), from T0 to T2 in the in-TEM, ex-TEM, and fib-TEM profiles (P = 0.012, P = 0.037, and P = 0.0001, respectively), and from T1 to T2 in the fib-TEM profile (P = 0.039) were noted. The α angle increased from T0 to T2 in the in-TEM and ex-TEM profiles (P = 0.019 and P = 0.036, respectively). All results were, however, within the institutional reference ranges., Conclusions: In this study, unlike the hypercoagulability observed in human orthopedic patients, a hypercoagulable state as measured by thromboelastometry did not develop in dogs following orthopedic surgery., (© Veterinary Emergency and Critical Care Society 2015.)

Objective: To investigate hemostatic changes in dogs envenomed by cytotoxic (African puffadder) and neurotoxic snakes (snouted cobra) using thromboelastography (TEG) and plasma-based coagulation assays., Design: Prospective observational clinical study., Setting: University teaching hospital., Animals: Eighteen client-owned dogs; 9 envenomed by African puffadder (Bitis arietans) and 9 by snouted cobra (Naja annulifera). Ten healthy dogs served as controls., Interventions: None., Measurements and Main Results: Blood was collected at presentation and 24 hours post envenomation. Platelet count, TEG, prothrombin time, activated partial thromboplastin time (aPTT), antithrombin activity, and fibrinogen (Fib) and C-reactive protein (CRP) concentrations were measured. Outcomes were analyzed using linear mixed models at 5% significance. At presentation, R time was significantly prolonged in the puffadder group compared to the cobra (P = 0.01) and control groups (P = 0.05). Platelet count was significantly lower in the puffadder compared to the cobra (P = 0.04) and control groups (P = 0.001), respectively. Antithrombin activity was significantly decreased in the puffadder (P = 0.002) and cobra groups (P = 0.004) compared to the control group. Both prothrombin time and activated partial thromboplastin time were significantly prolonged in the cobra group compared to the control group (P = 0.03 for both). The TEG variables, maximum amplitude (MA) and G, were significantly increased 24 hours post envenomation in the puffadder group compared to their values at presentation (P = 0.05 for both). Fib and CRP concentrations were significantly increased 24 hours post envenomation in both snake-envenomed groups., Conclusions: Prolonged clot initiation was a common feature in puffadder-envenomed dogs at presentation and this was likely venom induced. Snouted cobra-envenomed dogs were normo- to hypercoagulable at presentation. Dogs from both puffadder and cobra groups progressed to a more hypercoagulable by 24 hours post envenomation, most likely due to marked inflammation as indicated by the increased Fib and CRP concentrations. TEG proved a sensitive tool for detecting abnormal hemostasis in snake-envenomed dogs., (© Veterinary Emergency and Critical Care Society 2014.)

Objective: To characterize the overall hemostatic changes in dogs envenomated by crotaline snakes via kaolin-activated thromboelastography (TEG), and to determine any prognostic/monitoring value from a TEG tracing on presentation, as well as during treatment with antivenom therapy., Design: Prospective observational, cohort study., Setting: University teaching hospital and primary emergency hospital., Animals: Thirty-eight dogs envenomated by crotaline snakes., Interventions: TEG tracings were evaluated on presentation to the hospital (pre) as well as immediately following (post) and 12 hours (12 h post) after antivenom treatment, if administered., Measurements and Main Results: At presentation, data were available for 38 dogs envenomated by crotaline snakes. Twenty dogs were in Group 1 (Antivenin [Crotalidae] Polyvalent antivenom), 12 dogs were in Group 2 (Antivipmyn antivenom), and 6 dogs in Group 3 that were not treated with antivenom. The average number of vials administered to group 1 and 2 were equal at 2.2. On presentation, based on a G value < TEG reference range, 15/38 (39%) of the dogs had hypocoagulable TEG tracings. There was a significant increase in G and MA value from the pre and 12 hour post measurement (P = 0.0001 and 0.0003, respectively), as well as from the post to 12 hour post measurement (P = 0.003 and, 0.014, respectively). During the study, 5 of 38 dogs died (13%) and of the dogs that died, 4/5 (80%) had angle and MA equal to zero on presentation. A decreased G and MA were significantly associated with mortality (P = 0.02 and 0.04, respectively)., Conclusions: A hypocoagulable TEG tracing, particularly a decreased G value and MA, is associated with an increased mortality in crotaline snake envenomation. G and MA also demonstrate a significant increase over treatment time., (© Veterinary Emergency and Critical Care Society 2014.)