The effect of unfractionated heparin on thrombelastographic analysis in healthy dogs

Objective – To determine the effect of single and multiple doses of SQ heparin (200 U/kg) on the thrombelastogram of healthy dogs. Design – Prospective study. Setting – University research facility. Animals – Six random‐source female dogs. Interventions – Baseline parameters, including a CBC with platelet count, prothrombin time, activated partial thromboplastin time (aPTT), and antithrombin were performed. Thrombelastography (TEG) and aPTT were performed hourly for 12 hours after unfractionated heparin dosing (200 U/kg, SQ). Anti‐Xa activity was assayed at 0, 3, 6, and 8 hours. Heparin was then administered every 8 hours for 3 days. The sampling protocol on Day 4 was identical to Day 1. Measurements and Main Results – On Day 1, percentage change from baseline for TEG parameter R, as well as absolute values of K, angle, and maximum amplitude (MA) were evaluated. Statistically significant (P<0.01) prolongation of the R time and a decrease in angle and MA was seen in all dogs by hour 3. R and MA were unmeasurable for most dogs between 3 and 5 hours. All TEG tracings returned to baseline by 12 hours. Day 4 TEG tracings mimicked those on Day 1. Only 1 dog achieved aPTT values outside the reference interval on both days. Anti‐Xa activity levels increased on Day 4 but not on Day 1. Based on post hoc in vitro analysis, prolongation of R time occurred at plasma heparin levels as low as 0.075 U/mL, well below the lower limit of detection of the anti‐Xa activity level assay. Conclusions – Administration of SQ heparin results in progressive changes in the TEG tracing, with maximal change occurring 3–5 hours after dosing. The extensive prolongation of the R time also indicates that TEG may be too sensitive and limits its utility as a monitoring tool for unfractionated heparin therapy.     

Changes in the coagulation parameters in dogs with protein-losing enteropathy between before and after treatment

Protein-losing enteropathy (PLE) is known to induce hypercoagulability and resultant thromboembolism in dogs. We hypothesized that hypercoagulability would improve if remission was obtained in dogs with PLE after treatment. This study aimed to evaluate the changes in the coagulation parameters after treatment in dogs diagnosed with PLE. As coagulation parameters, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, thrombin-antithrombin complex (TAT), D-dimer, and antithrombin (AT) were measured. In addition to these parameters, rotational thromboelastometry (ROTEM), which evaluates the comprehensive coagulation and fibrinolysis reactions of whole blood, was conducted and the data of clotting time (CT), clot formation time (CFT), α angle (α), maximum clot firmness (MCF) and lysis index at 60 min (LI60) were obtained. Eleven of the 14 dogs diagnosed with PLE were classified as responders to the treatment based on the changes in their plasma albumin (ALB) concentration after treatment. Significant increase in CFT and decrease of α and MCF indicating the resolution of hypercoagulability were found after treatment in responder dogs; however, there was no significant change in the coagulation and fibrinolysis parameters other than those measured by ROTEM. This study demonstrated that the hypercoagulability detected by ROTEM was significantly improved after treatment in dogs with PLE.     

Incidence of prolonged prothrombin time in dogs following gastrointestinal decontamination for acute anticoagulant rodenticide ingestion

Objective: To determine the effect of gastrointestinal (GI) decontamination on the incidence of prolonged prothrombin time (PT) in dogs after anticoagulant rodenticide ingestion. Design: Retrospective study. Setting: Urban emergency room. Animals: One hundred and fifty‐one client‐owned dogs. Measurements: Dogs presented to the emergency room within 6 hours of ingestion of an anticoagulant rodenticide and had a PT measured within 2–6 days of toxicant ingestion before initiating vitamin K therapy were included. Dogs were categorized as treated or untreated based on the institution of vitamin K therapy following PT testing. The signalment, body weight, type of rodenticide ingested, time elapsed between ingestion and initial presentation, method(s) of GI decontamination, and the times elapsed between both toxicant ingestion and initial hospital presentation until determination of PT were recorded. The PT results were recorded as well as any treatment received following the recheck examination. Any reported incidents of bleeding or untoward effects between exposure and reexamination were recorded. Main results: Of 151 dogs, only 11 dogs (8.3%) developed prolonged PT requiring vitamin K supplementation. None of the 11 dogs with prolonged PTs exhibited signs of bleeding or required transfusion therapy. No differences in age, weight, or time elapsed between treated and untreated patients were found. Conclusions: The incidence of prolonged PT is low in dogs receiving GI decontamination within 6 hours of anticoagulant rodenticide ingestion. Delaying vitamin K therapy until a PT has been assessed 48–72 hours after initial exposure appears to be safe and sensitive in dogs following anticoagulant rodenticide ingestion.     

不同乳蛋白组分对牛乳酶凝乳特性的影响

研究不同乳蛋白组分对牛乳酶凝乳特性的影响,在脱脂牛乳中添加乳清蛋白浓缩物(whey protein concentrate,WPC)、κ-酪蛋白(κ-casein,κ-CN)、β-乳球蛋白(β-lactoglobulin,β-Lg_A和β-Lg_B)。结果表明:这些乳蛋白组分可以缩短牛乳的酶凝乳时间,而且增加凝乳后的样品黏度,凝乳样品微观结构更加紧密;而添加α-乳白蛋白(α-lactalbumin,α-La)、α-酪蛋白(α-casein,α-CN)、β-酪蛋白(β-casein,β-CN)和总酪蛋白(casein,CN)对凝乳的形成具有抑制作用,凝乳样品微观结构较疏松。采用动态光散射法测定酶凝乳过程中酪蛋白胶束分子粒径的分布情况,结果表明,酪蛋白溶液中添加WPC、κ-CN、β-Lg_A和β-Lg_B后,分子半径分布发生变化,蛋白分子趋于聚集。选择酶凝乳差异明显的原料乳样品进行双向电泳与质谱鉴定,结果表明,与牛乳的酶凝乳特性相关的差异蛋白大多是影响乳腺细胞代谢的微量生物活性蛋白质。     

Changes of platelet function and blood coagulation during short-term storage of CPDA-1-stabilised ovine blood

The objective of this study was to detect the influence of short-term storage on the haemostatic function in whole citrated ovine blood at different storage temperatures. Ovine blood was collected in a commercial transfer bag system containing CPDA-1 and stored on a wobbler at room (20-25 °C; n = 5) or refrigerator temperature (4 °C; n = 5). The following analyses were performed initially and after 1, 2, 3, 4, 5, 6, 8, 12, 24, 48 and 72 h of storage: platelet count and (spontaneous) aggregates, agonist-induced platelet aggregation with two methods (impedance aggregometry, turbidimetric method), prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen concentration and resonance thrombography.Platelet count remained stable at room temperature, whereas a significant decrease was detected after 48 h storage at 4 °C. The latter was associated with the formation of a high percentage of platelet aggregates (50-60%) after 5 h storage. Decrease in platelet aggregation was significantly more pronounced when blood was stored at 4 °C. The plasmatic coagulation tests were stable within the observation period.Results indicate that platelet count and aggregability of CPDA-1-stabilised ovine blood is better preserved at room temperature and provides adequate haemostatic function for ex vivo experiments for one working day. Functional loss and high percentage of platelets within aggregates which were observed in ovine blood stored at refrigerator temperature have to be considered in blood transfusion in sheep.     

Evaluation of plasma antithrombin activity and D-dimer concentration in populations of healthy cats, clinically ill cats, and cats with cardiomyopathy

BACKGROUND: Current coagulation tests lack sensitivity and detect disseminated intravascular coagulation (DIC) only when it is severe. Measurement of antithrombin (AT) activity and D-dimer concentration permits early diagnosis and more precise classification of coagulopathies in some species. OBJECTIVES: The objectives of this study were to validate and determine the diagnostic utility of a chromogenic AT assay and an immunoturbidimetric D-dimer assay for the diagnosis of DIC in cats. METHODS: Citrated plasma samples were collected from 30 healthy cats, 30 ill cats, and 13 cats with cardiomyopathy. Partial thromboplastin time, prothrombin time, fibrin(ogen) degradation products, platelet concentration, and erythrocyte morphology were determined on all samples to document the presence or the absence of DIC. AT activity and D-dimer concentration were then measured. RESULTS: The chromogenic AT assay was linear and precise. Mean AT activity was higher in ill cats and cats with cardiomyopathy compared with healthy cats, but the difference was only significant in ill cats (P = .003). Seven cats met the criteria for DIC. Of the cats with DIC, 2 had decreased AT activity, 1 had increased AT activity, and 4 had AT activities within normal limits. The immunoturbidimetric D-dimer assay did not appear to accurately measure feline D-dimer. CONCLUSIONS: The chromogenic AT assay appeared to measure AT in cats but was not useful for the diagnosis of DIC. AT may be an acute phase reactant in cats. The immunoturbidimetric D-dimer assay was not useful for the diagnosis of DIC in cats.     

Blood coagulation times in the European brown hare (Lepus europaeus)

Background:  Many causes of mortality in the European brown hare, such as bacterial and viral infections, anticoagulant poisoning, and trauma, may result in hemorrhage. There are, however, no reference values concerning blood clotting in this species.  Objectives:  The aim of this study was to determine reference values for blood coagulation times and related parameters in healthy European brown hares.  Methods:  Blood samples from 30 clinically healthy adult hares (15 males and 15 females) were obtained. Hares were physically restrained for blood collection from the cephalic vein into tubes containing citrate and EDTA.  Results:  Mean ± SD were obtained for thrombin time (TT) (13.97 ± 1.37 seconds), prothrombin time (PT) (13.32 ± 2.15 seconds), activated partial thromboplastin time (APTT) (16.73 ± 1.86 seconds), fibrinogen concentration (2.98 ± 1.06 g/L), and platelet count (355.28 ± 128.73 × 10⁹/L). Conclusions: Reference values for blood coagulation times and other parameters associated with blood clotting will be useful in the laboratory evaluation of hemorrhage in the European brown hare.