Journal of Veterinary Emergency and Critical Care, Aug 10, 2023
ObjectiveTo evaluate a point‐of‐care viscoelastic coagulation monitor (VCM Vet) for use in horses... more ObjectiveTo 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.DesignProspective observational study.SettingTwo university teaching hospitals.AnimalsHealthy adult horses (n = 68).InterventionsNone.Measurements and Main ResultsBlood 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.ConclusionsVCM 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.
Hydroxyethyl starch, with an average molecular weight 600 kd and degree of substitution 0.7 (HES)... more Hydroxyethyl starch, with an average molecular weight 600 kd and degree of substitution 0.7 (HES), is an artificial colloid solution commonly used in veterinary medicine. HES has been shown to decrease platelet function in humans in vivo, indicated by prolonged closure times (CT) as measured by the Platelet Function Analyzer- 100s (PFA-100s). HES has also been shown to decrease canine platelet function in vitro by prolonging CT. Our hypothesis was that intravenous HES in vivo prolongs CT in dogs. Eight healthy, employee-owned dogs were included in the treatment group. Four of these dogs also served as the control group. Washout period between experimental protocols for the control group was a minimum of 4 weeks. Baseline platelet count was greater than 100,000/ml in all dogs. CTs were measured using collagen and adenosine diphosphate platelet agonists. Dogs were given 20 mL/kg of either NaCl 0.9% (control group, n54) or HES (treatment group, n58) IV over one hour. Blood was drawn for CT before the infusion, and at 1, 3, 5, and 24 hours after the start of the infusion. Two-way repeated measures analysis of variance was used to assess changes over time, and differences between control and treatment groups. Time-specific group differences were evaluated using Student’s t-test with a sequentially rejective method of multiple comparison adjustment. There was a significant change over time from 0 to 24 hours (p50.0001), a significant difference between groups across time (p50.0004), and evidence of a significant group-by-time interaction (p50.0069). At 3 hours, mean CT for the treatment group was 122.3 _ 18.1 seconds, which was significantly different (p50.0002) from the control group (71.0 _ 3.5 seconds). At 5 hours, mean CT for the treatment group was 142.7 _ 33.9 seconds, which was significantly different (p50.0014) from the control group (75.0 _ 8.6 seconds). Mean CT at 24 hours was within the reference interval for both the control and treatment group (66.0 _ 2.9 seconds and 81.8 _ 11.9 seconds respectively), however CT in three individual dogs in the treatment group at this time point remained prolonged. Given these results, a clinically relevant dose of HES adversely affects platelet function, as assessed by closure time. Individual dogs may still have decreased platelet function 24 hours after a single 20 mL/kg dose of HES, and therefore, an increased risk of bleeding.
Background: Cats with hypertrophic cardiomyopathy (HCM) are at risk for development of systemic t... more Background: Cats with hypertrophic cardiomyopathy (HCM) are at risk for development of systemic thromboembolic disease. However, the relationship between platelet activation state and cardiovascular parameters associated with HCM is not well described. Objectives: To characterize platelet activation by flow cytometric evaluation of platelet P-selectin and semiquantitative Western blot analysis of soluble platelet-endothelial cell adhesion molecule-1 (sPECAM-1). Animals: Eight normal healthy cats (controls) owned by staff and students of the School of Veterinary Medicine and 36 cats from the UC Davis Feline HCM Research Laboratory were studied. Methods: Platelet-rich plasma (PRP) was used for all flow cytometry studies. Platelet surface CD41 and P-selectin expression were evaluated before and after ADP stimulation. sPECAM-1 expression was evaluated by Western blot analy-sis of platelet-poor plasma that had been stabilized with aprotinin. Standard echocardiographic studies were perfor...
Journal of Veterinary Emergency and Critical Care, 2021
OBJECTIVE To compare the efficacy of fresh frozen plasma (FFP) with cryopoor plasma (CPP) to trea... more OBJECTIVE To compare the efficacy of fresh frozen plasma (FFP) with cryopoor plasma (CPP) to treat vitamin K-dependent factor deficiency in a canine in vitro setting. DESIGN In vitro laboratory study. SETTING University veterinary medical teaching hospital. ANIMALS Seven units of FFP and 6 units of CPP from unique canine donors from the university veterinary blood bank. INTERVENTIONS Canine FFP was adsorbed by oral barium sulfate suspension to mimic vitamin K-dependent coagulopathy. A sequential mixing study was completed by adding FPP or CPP to the adsorbed plasma. Measurements of prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and factor activities of factors II, VII, and IX (FII, FVII, and FIX) were compared between the 2 treatment groups. MEASUREMENTS AND MAIN RESULTS When comparing the sequential addition of CPP or FPP to adsorbed plasma, the following had no statistical significance: PT (P = 0.94), aPTT (P = 0.66), FII (P = 0.05), and FIX (P = 0.90). There was a dose-dependent decrease with PT and aPTT and a dose-dependent increase with FII and FIX. In contrast, after the addition of either CPP or FFP, there was a significant difference between the treatment groups for the concentration of fibrinogen (P = 0.005) and activity of FVII (P = 0.044), with FFP resulting in a greater concentration of fibrinogen and CPP resulting in a greater concentration of FVII. Measurements of factor X (FX) were initially included in the study but were later excluded because FX appeared to be continually adsorbed even after the addition of CPP or FFP. CONCLUSIONS CPP partially corrected the coagulation times and concentration of vitamin K-dependent coagulation factors to the same degree as FFP. CPP, generally less expensive than FFP, may provide an alternative treatment option for vitamin K-dependent coagulopathies, although in vivo testing is needed.
Journal of Veterinary Emergency and Critical Care, Aug 10, 2023
ObjectiveTo evaluate a point‐of‐care viscoelastic coagulation monitor (VCM Vet) for use in horses... more ObjectiveTo 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.DesignProspective observational study.SettingTwo university teaching hospitals.AnimalsHealthy adult horses (n = 68).InterventionsNone.Measurements and Main ResultsBlood 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.ConclusionsVCM 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.
Hydroxyethyl starch, with an average molecular weight 600 kd and degree of substitution 0.7 (HES)... more Hydroxyethyl starch, with an average molecular weight 600 kd and degree of substitution 0.7 (HES), is an artificial colloid solution commonly used in veterinary medicine. HES has been shown to decrease platelet function in humans in vivo, indicated by prolonged closure times (CT) as measured by the Platelet Function Analyzer- 100s (PFA-100s). HES has also been shown to decrease canine platelet function in vitro by prolonging CT. Our hypothesis was that intravenous HES in vivo prolongs CT in dogs. Eight healthy, employee-owned dogs were included in the treatment group. Four of these dogs also served as the control group. Washout period between experimental protocols for the control group was a minimum of 4 weeks. Baseline platelet count was greater than 100,000/ml in all dogs. CTs were measured using collagen and adenosine diphosphate platelet agonists. Dogs were given 20 mL/kg of either NaCl 0.9% (control group, n54) or HES (treatment group, n58) IV over one hour. Blood was drawn for CT before the infusion, and at 1, 3, 5, and 24 hours after the start of the infusion. Two-way repeated measures analysis of variance was used to assess changes over time, and differences between control and treatment groups. Time-specific group differences were evaluated using Student’s t-test with a sequentially rejective method of multiple comparison adjustment. There was a significant change over time from 0 to 24 hours (p50.0001), a significant difference between groups across time (p50.0004), and evidence of a significant group-by-time interaction (p50.0069). At 3 hours, mean CT for the treatment group was 122.3 _ 18.1 seconds, which was significantly different (p50.0002) from the control group (71.0 _ 3.5 seconds). At 5 hours, mean CT for the treatment group was 142.7 _ 33.9 seconds, which was significantly different (p50.0014) from the control group (75.0 _ 8.6 seconds). Mean CT at 24 hours was within the reference interval for both the control and treatment group (66.0 _ 2.9 seconds and 81.8 _ 11.9 seconds respectively), however CT in three individual dogs in the treatment group at this time point remained prolonged. Given these results, a clinically relevant dose of HES adversely affects platelet function, as assessed by closure time. Individual dogs may still have decreased platelet function 24 hours after a single 20 mL/kg dose of HES, and therefore, an increased risk of bleeding.
Background: Cats with hypertrophic cardiomyopathy (HCM) are at risk for development of systemic t... more Background: Cats with hypertrophic cardiomyopathy (HCM) are at risk for development of systemic thromboembolic disease. However, the relationship between platelet activation state and cardiovascular parameters associated with HCM is not well described. Objectives: To characterize platelet activation by flow cytometric evaluation of platelet P-selectin and semiquantitative Western blot analysis of soluble platelet-endothelial cell adhesion molecule-1 (sPECAM-1). Animals: Eight normal healthy cats (controls) owned by staff and students of the School of Veterinary Medicine and 36 cats from the UC Davis Feline HCM Research Laboratory were studied. Methods: Platelet-rich plasma (PRP) was used for all flow cytometry studies. Platelet surface CD41 and P-selectin expression were evaluated before and after ADP stimulation. sPECAM-1 expression was evaluated by Western blot analy-sis of platelet-poor plasma that had been stabilized with aprotinin. Standard echocardiographic studies were perfor...
Journal of Veterinary Emergency and Critical Care, 2021
OBJECTIVE To compare the efficacy of fresh frozen plasma (FFP) with cryopoor plasma (CPP) to trea... more OBJECTIVE To compare the efficacy of fresh frozen plasma (FFP) with cryopoor plasma (CPP) to treat vitamin K-dependent factor deficiency in a canine in vitro setting. DESIGN In vitro laboratory study. SETTING University veterinary medical teaching hospital. ANIMALS Seven units of FFP and 6 units of CPP from unique canine donors from the university veterinary blood bank. INTERVENTIONS Canine FFP was adsorbed by oral barium sulfate suspension to mimic vitamin K-dependent coagulopathy. A sequential mixing study was completed by adding FPP or CPP to the adsorbed plasma. Measurements of prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and factor activities of factors II, VII, and IX (FII, FVII, and FIX) were compared between the 2 treatment groups. MEASUREMENTS AND MAIN RESULTS When comparing the sequential addition of CPP or FPP to adsorbed plasma, the following had no statistical significance: PT (P = 0.94), aPTT (P = 0.66), FII (P = 0.05), and FIX (P = 0.90). There was a dose-dependent decrease with PT and aPTT and a dose-dependent increase with FII and FIX. In contrast, after the addition of either CPP or FFP, there was a significant difference between the treatment groups for the concentration of fibrinogen (P = 0.005) and activity of FVII (P = 0.044), with FFP resulting in a greater concentration of fibrinogen and CPP resulting in a greater concentration of FVII. Measurements of factor X (FX) were initially included in the study but were later excluded because FX appeared to be continually adsorbed even after the addition of CPP or FFP. CONCLUSIONS CPP partially corrected the coagulation times and concentration of vitamin K-dependent coagulation factors to the same degree as FFP. CPP, generally less expensive than FFP, may provide an alternative treatment option for vitamin K-dependent coagulopathies, although in vivo testing is needed.
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