Evaluation of clopidogrel, hypercoagulability, and platelet count in dogs undergoing splenectomy for splenic masses.

Dogs that had splenectomy are predisposed to fatal thrombotic conditions, and thrombocytosis is a risk factor for post-splenectomy hypercoagulability. However, in veterinary medicine, there are no specific therapeutic approaches for managing this hypercoagulability. This study aimed to determine the preventive effect of clopidogrel on post-operative hypercoagulability during the first 2 weeks post-splenectomy in dogs with splenic masses. This study included 12 dogs that had splenectomy. Seven dogs received no treatment (group A), and five were treated with clopidogrel (group B). Clopidogrel was loaded at 10 mg/kg on day 2 and continued at 2 mg/kg until day 14. Blood samples were collected on the day of surgery and 2, 7, and 14 days after splenectomy in both groups. In group B, thromboelastography (TEG) was performed on the same days. In group A, there was significant elevation of platelet counts on days 7 (p = 0.007) and 14 (p = 0.001) compared to day 0. In group B, the platelet counts were significantly elevated on day 7 (p = 0.032) but no significant difference was found on day 14 compared to day 0. Platelet counts on day 14 were significantly higher in group A than in group B (p = 0.03). The lower platelet counts were correlated with alterations in TEG parameters, and no significant differences were found in the K and α-angle values at all postoperative assessment points compared to day 0. Our study suggests that clopidogrel may reduce post-operative thrombocytosis and hypercoagulability in dogs that undergo splenectomy for splenic masses.

DEVELOPING A THROMBOELASTOGRAPHY ASSAY IN ELASMOBRANCHS.

Thromboelastography (TEG) is a hemostatic assay evaluating clot initiation time, kinetics, strength, and extent of fibrinolysis. Hemostatic assays in nonmammalian species have been less extensively studied because of lack of taxon-specific reagents and unique physiology. Hemostatic or hemorrhagic disease has been described postmortem in elasmobranchs, but antemortem detection of coagulopathies is limited in this taxon. The study aimed to establish an elasmobranch TEG protocol to improve hemostatic evaluation and facilitate advanced treatment options for animals under human care. Multiple clotting initiators were assessed for efficacy with frozen-thawed citrated plasma, fresh citrated plasma, and fresh whole citrated blood: RapidTEGTM, citrated kaolin, Reptilase®, and species brain-derived thromboplastin prepared by two different methods. Initial evaluation found plasma samples clot inconsistently, but TEG analyses using fresh whole blood consistently led to measurable TEG reactions using multiple clotting initiators. The most reliable elasmobranch TEG results were observed using citrated fresh whole blood and the RapidTEG clot initiation reagent.

Evaluation of coagulation profile in dogs with ACTH-dependent hyperadrenocorticism compared to healthy dogs by rotational thromboelastometry (ROTEM).

Despite their low morbidity, thromboembolic events in hyperadrenocorticism are associated with high mortality. Identifying the main hemostatic abnormalities will improve the prophylactic approach of these canine patients. The aim of this study was to evaluate hemostatic alterations related with ACTH-dependent HAC and its association with hypercoagulable state. For this purpose, 25 dogs diagnosed with ACTH-dependent HAC were compared with 28 healthy dogs as a control group. The hemostatic variables included platelet count, antithrombin, fibrinogen, D-dimer, PT, aPTT, rotational thromboelastometry (ROTEM) and platelet aggregation. Results showed a hypercoagulable state in 32% (8/25) dogs by ROTEM, which had at least 2 of the next features: decreased coagulation time (CT) or clot formation time (CFT) on INTEM (5/25) or EXTEM (4/25); increased maximum clot firmness (MCF) on INTEM (9/25), EXTEM (6/25) and FIBTEM (9/25). These same variables had a significant difference (P≤ 0.05) compared with the control group, as well as the parameters of α-angle and CT. Median fibrinogen levels (310 vs.178 mg/dL), mean platelet aggregation (11.1 vs. 7.9 Ohms), median platelet count (360 vs. 225 ×103/µL) and mean antithrombin activity (140 vs. 119%) were increased in ACTH-dependent HAC dogs compared to control group. PT (7.1 vs. 8.0 seconds) and aPTT (11.6 vs. 15.2 seconds) were also shortened in ACTH-dependent HAC dogs. Our findings confirm the presence of a hypercoagulable tendency in dogs with HAC. Although multifactorial, fibrinogen concentration and MCF FIBTEM showed the relevance of this protein for hypercoagulability in HAC.

Comparison of coagulation and fibrinolysis in Irish Wolfhounds and age-matched control dogs using tissue plasminogen activator-augmented viscoelastic testing.

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.

Platelet hyperresponsiveness and increased platelet-neutrophil aggregates in dogs with myxomatous mitral valve disease and pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PH) in dogs with myxomatous mitral valve disease (MMVD) is caused by increased pulmonary venous pressure. Thrombosis, vascular remodeling, and vasoconstriction mediated by platelets could exacerbate PH. HYPOTHESIS: Dogs with PH will exhibit a hypercoagulable state, characterized by increased platelet activation, platelet-leukocyte, and platelet-neutrophil aggregate formation. ANIMALS: Eleven dogs (≥3.5 kg) diagnosed with MMVD and PH and 10 dogs with MMVD lacking PH. METHODS: Prospective cohort ex vivo study. All dogs underwent echocardiographic examination, CBC, 3-view thoracic radiographs, and heartworm antigen testing. Severity of PH and MMVD were assessed by echocardiography. Viscoelastic monitoring of coagulation was assessed using thromboelastography (TEG). Platelet activation and platelet-leukocyte/platelet-neutrophil interactions were assessed using flow cytometry. Plasma serotonin concentrations were measured by ELISA. RESULTS: Unstimulated platelets from dogs with MMVD and PH expressed more surface P-selectin than MMVD controls (P = .03). Platelets from dogs with MMVD and PH had persistent activation in response to agonists. The number of platelet-leukocyte aggregates was higher in dogs with MMVD and PH compared with MMVD controls (P = .01). Ex vivo stimulation of whole blood resulted in higher numbers of platelet-neutrophil aggregates in dogs with MMVD and PH (P = .01). Assessment of hypercoagulability based on TEG or plasma serotonin concentrations did not differ between groups. CONCLUSION AND CLINICAL IMPORTANCE: Platelet hyperresponsiveness and increased platelet-neutrophil interaction occur in dogs with MMVD and PH, suggesting that platelets play a role of in the pathogenesis of PH. Clinical benefits of antiplatelet drugs in dogs with MMVD and PH require further investigation.

Evaluation of coagulation and platelet activation state and function in heartworm-infected dogs.

BACKGROUND: Enhanced platelet responses have been demonstrated in heartworm-infected (HWI) dogs; however, the cause and clinical implications of altered platelet function have not been fully elucidated. OBJECTIVE: This study evaluated platelet function in HWI dogs. METHODS: Anticoagulated whole blood collected from eight HWI and eight uninfected dogs was evaluated using turbidometric platelet aggregometry, a platelet function analyzer (PFA-100), a total thrombus analysis system (T-TAS), tissue factor-activated and tissue plasminogen activator modified thromboelastography (TF- and tPA-TEG), CBC, von Willebrand Factor activity, and fibrinogen concentrations. Platelet activation state and the presence of reticulated platelets were assessed via flow cytometric expression of P-selection (CD-62P) and thiazole orange staining. RESULTS: Platelet aggregation responses to adenosine diphosphate (ADP, 10 µM) or collagen (20 µg/mL), PFA-100 closure times, and T-TAS occlusion times did not differ between groups. TEG values TF-R, tPA-R, TF-K, and TF-LY60 were decreased (P = .025, P = .047, P = .038, P = .025) and TF-MA, tPA-MA, TF-G, tPA-G and TF-alpha angle were increased (P < .04) in HWI dogs. HWI dogs had higher fibrinogen concentrations (465.6 ± 161 mg/dL vs 284.5 ± 38 mg/dL, P = .008) and eosinophil counts (0.686 ± 0.27 × 103/µL vs 0.267 ± 0.20 × 103/µL, P = .003). There was no difference in hematocrit, activation state, or percent of reticulated platelets. Non-activated reticulated platelets exhibited higher CD62P expression compared with mature platelets. CONCLUSIONS: Chronic canine heartworm disease was accompanied by hypercoagulability, hyperfibrinogenemia, and decreased fibrinolysis. Enhanced platelet activation was not identified in this group of HWI dogs.

Hypercoagulability based on thromboelastography is common in dogs undergoing adrenalectomy.

OBJECTIVE: Thromboelastography (TEG) is a whole blood assay that yields global assessment of hemostasis, as it evaluates clot time, strength, and kinematics of clot formation and lysis. The main objective was to describe preoperative TEG findings in dogs that had an adrenalectomy performed and, secondarily, to describe TEG findings in the dogs with or without hyperadrenocorticism (HAC). ANIMALS: 30 dogs that had preoperative TEG and adrenalectomy performed. METHODS: Medical records between 2018 and 2022 were reviewed. Signalment, diagnostic data, and perioperative treatment were abstracted. RESULTS: 53% (16/30) of the dogs were hypercoagulable, and none were hypocoagulable. Based on histopathology, 6 of 9 dogs with adenocarcinoma were hypercoagulable, 4 of 8 with pheochromocytoma were hypercoagulable, and 6 of 10 with adenoma were hypercoagulable. None of the 3 dogs with other histopathologic diagnoses or combinations of diagnoses (adrenocortical hyperplasia, poorly differentiated sarcoma, and both adrenocortical adenocarcinoma and pheochromocytoma) were hypercoagulable. Of the 14 dogs tested preoperatively for HAC, 4 of 8 HAC dogs were hypercoagulable and 2 of 6 non-HAC dogs were hypercoagulable. CLINICAL RELEVANCE: The present report describes for the first time TEG findings for dogs undergoing adrenalectomy and suggests that the majority of dogs with adrenal neoplasia are hypercoagulable based on TEG results.

Thromboelastometry for assessment of hemostasis and disease severity in 42 dogs with naturally-occurring heatstroke.

BACKGROUND: Thromboelastometry (TEM) provides a comprehensive overview of the entire coagulation process and has not been evaluated in heatstroke-induced coagulopathies in dogs. OBJECTIVES: To determine the diagnostic and prognostic utility of TEM in dogs with heatstroke. ANIMALS: Forty-two client-owned dogs with heatstroke. METHODS: Prospective observational study. Blood samples for intrinsic and extrinsic TEM (INTEM and EXTEM, respectively) were collected at presentation and every 12 to 24 hours for 48 hours. Coagulation phenotype (hypo-, normo-, or hypercoagulable) was defined based on TEM area under the 1st derivative curve (AUC). RESULTS: Case fatality rate was 31%. Median TEM variables associated with death (P < .05 for all) included longer INTEM clotting time, lower AUC at presentation and at 12 to 24 hours postpresentation (PP), lower INTEM alpha angle, maximum clot firmness, and maximum lysis (ML) at 12 to 24 hours PP, and lower EXTEM ML at 12 to 24 hours PP. Most dogs were normo-coagulable on presentation (66% and 63% on EXTEM and INTEM, respectively), but hypo-coagulable 12 to 24 PP (63% for both EXTEM and INTEM). A hypo-coagulable INTEM phenotype was more frequent at presentation and 12 to 24 PP among nonsurvivors compared to survivors (55% vs 15% and 100% vs 50%, P = .045 and .026, respectively). AKI was more frequent (P = .015) in dogs with hypo-coagulable INTEM tracings at 12 to 24 hours. Disseminated intravascular coagulation was more frequent (P < .05) in dogs with a hypo-coagulable INTEM phenotype and in nonsurvivors at all timepoints. CONCLUSIONS AND CLINICAL RELEVANCE: Hypocoagulability, based on INTEM AUC, is predictive of worse prognosis and occurrence of secondary complications.

Thromboelastographic evaluation of the effectiveness of choline or CDP-choline treatment on endotoxin-induced hemostatic alterations in dogs.

Sepsis/endotoxemia associates with coagulation abnormalities. We showed previously that exogenous choline treatment reversed the changes in platelet count and function as well as prevented disseminated intravascular coagulation (DIC) in endotoxemic dogs. The aim of this follow-up study was to evaluate the effect of treatment with choline or cytidine-5'-diphosphocholine (CDP-choline), a choline donor, on endotoxin-induced hemostatic alterations using thromboelastography (TEG). Dogs were randomized to six groups and received intravenously (iv) saline, choline (20 mg/kg) or CDP-choline (70 mg/kg) in the control groups, whereas endotoxin (0.1 mg/kg, iv) was used alone or in combination with choline or CDP-choline at the same doses in the treatment groups. TEG variables including R- and K-time (clot formation), maximum amplitude (MA) and α-angle (clot stability), G value (clot elasticity), and EPL, A, and LY30 (fibrinolysis), as well as overall assessment of coagulation (coagulation index - CI), were measured before and at 0.5-48 h after the treatments. TEG parameters did not change significantly in the control groups, except for CI parameter after choline administration. Endotoxemia resulted in increased R-time and A value (P < 0.05), decreased K-time (P < 0.05), α-angle (P < 0.001) and CI values (P < 0.01) at different time points. Treatment with either choline or CDP-choline attenuated or prevented completely the alterations in TEG parameters in endotoxemic dogs with CDP-choline being more effective. These results confirm and extend the effectiveness of choline or CDP-choline in endotoxemia by further demonstrating their efficacy in attenuating or preventing the altered viscoelastic properties of blood clot measured by TEG.

Assessment of hemostasis in hyperthyroid and euthyroid cats using two viscoelastic assays and platelet aggregometry.

BACKGROUND: Hyperthyroidism in humans is associated with a hypercoagulable state and an increased risk of thromboembolism. OBJECTIVE: To evaluate hemostatic variables in hyperthyroid and euthyroid cats with the hypothesis that hyperthyroid cats will have evidence of altered hemostasis consistent with a potential hypercoagulable state. ANIMALS: Client-owned hyperthyroid (n = 16) and euthyroid (n = 15) cats over 8 years of age. METHODS: Prospective observational study. Hyperthyroid and euthyroid cats were enrolled. Rotational thromboelastometry (ROTEM), whole-blood platelet impedance aggregometry (WBPIA) and a point-of-care viscoelastic coagulation monitor (VCM-Vet) were performed immediately after minimally traumatic venipuncture under sedation. RESULTS: Hyperthyroid cats had significantly higher values for variables as assessed by VCM-Vet: A10 (34 [17-47] vs 25 [17-38], P = .003); A20 (39.5 [23-55] vs 31 [21-45], P = .003); and MCF (41 [24-58] vs 35 [22-49], P = .03). Hyperthyroid cats had significantly different values versus the euthyroid cohort as assessed by different ROTEM channels: increased A10, INTEM (61.5 [39-75] vs 54 [23-66], P = .007) and FIBTEM (18 [10-35] vs 13 [2-27], P = .01); increased A20, INTEM (68 [45-78] vs 61 [30-70], P = .006) and FIBTEM (17 [10-34] vs 11 [2-25], P = .002); increased MCF, EXTEM (72 [65-81] vs 69 [34-78], P = .04), INTEM (70 [45-85] vs 62 [35-71], P = .01) and FIBTEM (18 [13-37] vs 14 [3-27], P = .02); increased alpha angle, EXTEM (80 [68-85] vs 76 [41-84], P = .01); shortened CT, EXTEM (52.5 [29-73] vs 60 [52-92], P = .003) and FIBTEM (52.5 [16-75] vs 65 [53-165], P = .001); and decreased ML, FIBTEM (20 [1-36] vs 33 [19-59], P <.001). No significant differences were found with WBPIA. CONCLUSIONS AND CLINICAL IMPORTANCE: The hyperthyroid cats in this study had evidence of altered hemostasis as assessed by 2 viscoelastic methodologies, and characterized by increased clot amplitude, firmness, and faster coagulation times vs euthyroid controls.

INVESTIGATION OF A POINT-OF-CARE VISCOELASTIC COAGULATION MONITOR AND ITS COMPARISON TO THROMBOELASTOGRAPHY IN CLINICALLY HEALTHY AFRICAN ELEPHANTS (LOXODONTA AFRICANA).

Elephant endotheliotropic herpesvirus (EEHV) can induce fatal hemorrhagic disease (HD) in African elephants (Loxodonta africana). Once clinical signs develop, progression is rapid, even with aggressive treatment. There is a critical need to develop point-of-care diagnostic tests to aid in identification of EEHV-HD prior to the onset of overt clinical signs. Study objectives were to investigate a novel, point-of-care viscoelastic coagulation monitor (VCM Vet), compare the results to thromboelastography (TEG), and report traditional hemostatic analytes in adult African elephants. Whole blood was collected from seven clinically healthy elephants (four females and three males, 18-47 yr) and analyzed in duplicate via VCM Vet and kaolin-activated TEG 1-3 and 30 min following collection, respectively. Separated plasma was frozen for ancillary coagulation testing. Both analyses generated quantifiable clotting reactions with variables (median [range]) describing clot formation rate (VCM Vet, clot time = 682 s [530-987 s], clot formation time = 244 s [186-744 s], Alpha = 40° [14-47°]; TEG, reaction time = 6.2 min [3.7-11.8 min], kinetic time = 1.3 min [0.9-2.6 min], Alpha = 70° [57-77°]), clot strength (VCM Vet, maximum clot formation = 34 units [20-45 units]; TEG, maximum amplitude = 75 mm [69-80 mm], shear elastic modulus strength = 14.7 Kdynes/s [11.3-19.5 Kdynes/s]), and clot lysis (VCM Vet, lysis index at 30 min = 100% [100-99%], lysis index at 45 min = 98% [95-100%]; TEG, lysis index at 30 min = 0% [0-0.4%], lysis index at 60 min = 1.4% [0-2.6%]) recorded. Additional testing (median [range]) included D-dimer concentration (33 ng/ml [28-94 ng/ml]), prothrombin time (12.4 s [12.2-13.2 s]), activated partial thromboplastin time (17.2 s [14.2-18.8 s]), and fibrinogen concentration (297 [282-383] mg/dL). Tracings generated by VCM Vet and TEG were clinically similar, and there was visual agreement and minimal difference between quantitative variables for duplicate tests. VCM Vet is a promising, user-friendly tool for use in identification and management of coagulopathies in African elephants.

Comparison of D-dimer concentration and thromboelastography for diagnosis of cerebrovascular accidents in dogs: A retrospective study.

BACKGROUND: Cerebrovascular accidents (CVAs) in dogs are diagnosed using magnetic resonance imaging (MRI). This modality is sometimes unavailable, and CVAs can resemble other lesions on MRI. D-dimer concentration and thromboelastography (TEG) are utilized in human medicine in addition to diagnostic imaging to support diagnosis of CVAs, but their use in veterinary patients has not been assessed. OBJECTIVE: Assess utility of blood D-dimer concentration and TEG in supporting the imaging diagnosis of CVAs in dogs. ANIMALS: Sixty-eight client-owned dogs with neurologic signs that had brain MRI and D-dimer concentration or TEG performed. METHODS: Multicenter, retrospective study. The incidence of abnormal D-dimer concentration or TEG was compared between patients with MRI evidence of CVA and a control population. Analysis methods included Fisher's exact test or Chi-squared test for association and comparison of independent proportions. RESULTS: Neither D-dimer concentration nor TEG was significantly associated with a CVA (P = .38 and .2, respectively). D-dimer testing was performed in a low-risk population and showed low sensitivity (30.8%; 95% confidence interval [CI], 10%-61%) and high specificity (86.4%; 95% CI, 64%-96%) for CVA diagnosis. Thromboelastography was performed in a high-risk population and showed moderate sensitivity (64.3%; 95% CI, 44%-81%) and specificity (66.7%; 95% CI, 24%-94%) for CVA diagnosis. Abnormal D-dimer concentration or TEG were not helpful in differentiating hemorrhagic from ischemic stroke (P = .43 and .41, respectively). CONCLUSIONS: Although blood D-dimer concentration or TEG alone are not diagnostic of CVAs in dogs, a positive D-dimer result supports additional testing for CVA.

The effect of ε-aminocaproic acid on blood product requirement, outcome and thromboelastography parameters in severely thrombocytopenic dogs.

BACKGROUND: No treatment other than platelet administration is known to protect against spontaneous hemorrhage in thrombocytopenic dogs. OBJECTIVES: Primary: determine if treatment with ε-aminocaproic acid (EACA) decreases the requirement for blood transfusions and improves outcome in dogs with severe thrombocytopenia. Secondary: find evidence of hyperfibrinolysis and determine the effect EACA administration on rapid (rTEG) and tissue plasminogen activator-spiked (tPA-rTEG) thromboelastography parameters. ANIMALS: Twenty-seven dogs with severe thrombocytopenia were treated with EACA, and data from an additional 33 were obtained from the hospital database as historical control (HC) cohort. METHODS: Single arm clinical trial with HCs. The EACA group dogs received EACA (100 mg/kg IV followed by a constant-rate infusion [CRI] of 400 mg/kg/24 hours). Thromboelastography before and during EACA infusion, hospitalization days, number of transfusions, and mortality were compared. RESULTS: No difference was found in number of transfusions per dog (median, interquartile range; 1, 0-2.5 vs 0.9, 0-2; P = .5) and hospitalization days (4, 4-6 vs 4.5, 3.75-6; P = .83) between HC and EACA groups, respectively, and no difference in survival was identified by log-rank analysis (P = .15). Maximum amplitude on both rTEG and tPA-rTEG increased after EACA administration (rTEG baseline: 23.6, 9.6-38.9; post-EACA: 27.3, 19.8-43.2; P < .001; tPA-rTEG baseline: 23, 10.9-37.2; post-EACA: 24.7, 16.7-44.8; P < .002). CONCLUSIONS AND CLINICAL IMPORTANCE: Although EACA increased clot strength, there was no effect on outcome. Treatment with EACA at this dosage cannot be recommended as a routine treatment but may be considered for dogs with severe ongoing hemorrhage.

Prospective evaluation of platelet function and fibrinolysis in 20 dogs with trauma.

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, r2  = -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.

Evaluation of hemostatic derangements associated with canine anaphylaxis and the relationship to syndrome severity.

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.

Thromboelastographic evaluation in dogs with Asian pit viper (Gloydius) envenomation.

The objective of this study was to investigate the thromboelastography (TEG) variables and platelet count after Asian pit viper (Gloydius) envenomation in dogs compared with healthy control dogs. Ten dogs with snake envenomation and twenty healthy dogs were included. There was a significant decrease in G (P=0.017), maximum amplitude (MA) (P=0.012), angle value (P=0.041), platelet count (P<0.001, as well as an increase in K value (P=0.034) and R value (P=0.007) in dogs with snake envenomation. The results of this study revealed that dogs with Asian pit viper (Gloydius) envenomation showed a hypocoagulable state compared with healthy dogs. Our findings may support the use of TEG for diagnosing and monitoring coagulopathy after Asian pit viper (Gloydius) envenomation in dogs.

Evaluation of the effect of etamsylate on thromboelastographic traces of canine blood with and without the addition of heparin.

The objective of this study was to investigate the effect of etamsylate on canine blood and heparinised canine blood from healthy dogs using thromboelastography (TEG). Citrated blood was obtained from twenty healthy client-owned dogs, and 3 experiments were performed. Experiment 1 compared TEG in blood versus blood with etamsylate (250 mM). Experiment 2 evaluated TEG in heparinised blood (1 U/mL) with and without the addition of etamsylate (250 mM). Experiment 3 evaluated dose escalation of etamsylate (control, 250 µM, 500 µM and 1000 µM) in heparinised blood (1 U/mL). The addition of etamsylate to canine blood in experiment 1 increased the percentage of clot lysis at 30 min (z = -2.103, p = .035) and 60 min (z = -1.988, p = .047), suggesting that etamsylate could have a fibrinolytic effect. When etamsylate was added to heparinised canine blood (1 U/mL), etamsylate produced a dose-dependent inhibition of the effect of heparin when higher concentrations of etamsylate were used (500 µM and 1000 µM). The linear mixed effects model showed significant increases in α angle and maximal amplitude when high dose etamsylate was added compared to the control. In conclusion, etamsylate could be used at higher doses to inhibit the effect of heparin in dogs when protamine might not be available. However, etamsylate might have a fibrinolytic effect when used in healthy dogs.

Preliminary evaluation of reference intervals for a point-of-care viscoelastic coagulation monitor (VCM Vet) in healthy adult horses.

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.

Thromboelastographic results and hypercoagulability in dogs with surgically treated hepatocellular adenoma and carcinoma: A Veterinary Society of Surgical Oncology prospective study.

BACKGROUND: The most common haemostatic abnormality in dogs with cancer is hypercoagulability. A transient hypercoagulability has been documented in people with hepatocellular carcinoma (HCC) that resolves within weeks following hepatic tumour resection. OBJECTIVE: The objective was to compare the haemostatic status of dogs with liver tumours and healthy control dogs, by comparing coagulation and thromboelastography (TEG) measurements at three time points. METHODS: Liver tumour and healthy control dogs receiving surgery for liver lobectomy and ovariohysterectomy, respectively, were prospectively enrolled. All dogs had blood collected at three time points: pre-operative, 24 h post-operative and ~2 weeks post-operative. Haematological and haemostatic values were compared across time points in each group using repeated measures ANOVA tests. RESULTS: Ten and eight dogs were enrolled for the liver and control groups, respectively. Platelet count was significantly higher in the liver group than the control group at all time points, but within the normal range (pre-operative: 438.7 vs. 300.9 × 109 /L, p = .0078; 24 h post-operative: 416.2 vs. 283.9 × 109 /L, p = .0123; 10-14 days post-operative: 524.6 vs. 317.3 × 109 /L, p = .0072). The measure of the overall coagulant state (G-value) was significantly increased for the liver group compared to the control group at all time points (pre-operative: 15.6 vs. 8.6 d/sc, p = .0003; 24 h post-operative: 18.3 vs. 11.2 d/sc, p = .039; 10-14 days post-operative: 15.1 vs. 9.6 d/sc, p = .015). CONCLUSION: The liver group was hypercoagulable based on elevated G-values at all time points compared to the control group. This hypercoagulability was attributed to the effect of hepatic tumours alone, and not secondary to surgery and anaesthesia.

Prolonged holding time and sampling protocol affects viscoelastic coagulation parameters as measured by the VCM-Vet™ using fresh equine native whole blood.

OBJECTIVES: Determine the effect of sample holding time and single sample reuse on viscoelastic coagulation parameters when using fresh equine native whole blood. ANIMALS: 8 healthy adult horses from a university teaching herd. PROCEDURES: Blood collected by direct jugular venipuncture (18 ga needle, 3 mL syringe) was held at 37 °C for 2, 4, 6, or 8 minutes according to 1 of 2 protocols. Syringes were gently inverted twice, a small amount of blood was expressed, testing cartridges were filled, and placed within the VCM-Vet™ device (Entegrion Inc). Protocol A: samples were processed from a single syringe. Protocol B: 4 syringes were drawn through a single needle. VCM-Vet™ measures assessed included clot time (CT), clot formation time (CFT), alpha angle (AA), amplitude at 10/20 minutes (A10/A20), maximal clot firmness (MCF), and lysis index at 30/45 minutes (LI30/LI45). Differences over time were examined using the Friedman test and post hoc Wilcoxon Rank Sum Test with Bonferroni correction, P ≤ .05. RESULTS: Following Protocol A, there was a significant effect of holding time for CT (P = .02), CFT (P = .04), and AA (P = .05). CT and AA decreased over time, while CFT increased. Samples handled by Protocol B showed no significant difference over time for any of the VCM-Vet™ parameters. CLINICAL RELEVANCE: Sample holding time and handling protocol impact VCM-Vet™ testing results of fresh equine native whole blood. Viscoelastic coagulation samples tested using the VCM-Vet™ may be held unagitated for up to 8 minutes after collection while warm, but should not be reused.