We examined the effects of oral administration of Yunnan Baiyao (YB) on hemostasis by measuring buccal mucosal bleeding times (BMBTs) and doing citrated kaolin-activated whole-blood thromboelastography (TEG). In a randomized controlled crossover trial 8 beagle dogs were given either placebo or 1000 mg of YB orally every 12 h for 5 consecutive treatments. Blood was drawn 24 h before treatment and 2 and 24 h after the last treatment, and the BMBT was measured in each sample in duplicate. The TEG analysis was done in duplicate 60 ± 5 min after sample collection. There were no adverse effects of treatment and no significant differences between the control and treatment BMBTs or TEG parameters at any time point. Significant differences were found between baseline and 24 h after the last treatment within the treatment group for the TEG parameters LY30 and LY60 and within the control group for the TEG parameters MA, G, LY30, and LY60. Thus, at the dose and frequency of administration in this study YB did not appear to have any clinically significant effects on the measured coagulation parameters. The differences within the treatment group were likely due to analytic error since similar differences were seen in the control group. Further studies with a larger sample, as well as more direct measures of platelet function, are needed.

The objective of this study was to characterize the highly elevated levels of clotting factor VIII (FVIII) in camel plasma. Whole blood was collected from healthy camels and factor VIII clotting activity (FVIII:C) assays were conducted using both the clotting and the chromogenic techniques. The anticoagulant citrate phosphate dextrose adenine (CPDA) produced the highest harvest of FVIII:C, the level of plasma factor VIII, compared to heparin:saline and heparin: CPDA anticoagulants. Camel FVIII can be concentrated 2 to 3 times in cryoprecipitate. There was a significant loss of camel FVIII when comparing levels of FVIII in camel plasma after 1 h of incubation at 37°C (533%), 40°C (364%), and 50°C (223%). Thrombin generation of camel plasma is comparable to that of human plasma. It was concluded that camel plasma contains very elevated levels of FVIII:C, approaching 8 times the levels in human plasma, and that these elevated levels could not be attributed to excessive thrombin generation. Unlike human FVIII:C, camel FVIII:C is remarkably heat stable. Taken together, these unique features of camel FVIII could be part of the physiological adaptation of hemostasis of the Arabian camel in order to survive in the hot desert environment.

Twenty-four horses were randomly allocated to 3 groups. All horses underwent a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls, group-2 horses underwent 6 hours of colonic ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline blood samples were collected, then low-flow colonic ischemia was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. All horses were monitored for 6 hours. Citrated systemic venous (SV) blood samples were collected from the main pulmonary artery, and colonic venous (CV) samples were collected from the colonic vein draining the ventral colon. Samples were collected at 0, and 2, 3, 3.25, 4, and 6 hours for determination of one-stage prothrombin time, activated partial thromboplastin time, antithrombin III activity, and fibrinogen concentration. Data were analyzed statistically, using two-way ANOVA for repeated measures, and post-hoc comparisons were made by use of Student Newman Keul's test. Statistical significance was set at P < 0.05. There were significant decreases in all hemostatic variables by 2 hours in SV and SV samples from horses of all 3 groups, but there were no differences among the 3 groups for any of these variables. These hemostatic alterations could have been secondary to a hypercoagulable state or to fluid therapy-induced hemodilution. Colonic ischemia-reperfusion was not the cause of these alterations because these alterations also were observed in the sham-operated control horses. Significant temporal alterations existed even after accounting for the hemodilution. The most plausible explanation for these alterations is that hemostatic activation was incited by the celiotomy and manipulation of the colon during exteriorization and instrumentation. Comparison of paired SV and CV samples for each hemostatic variable revealed significant differences for the absolute values of one-stage prothrombin time and fibrinogen concentration, but not for activated partial thromboplastin time or antithrombin III activity. This indicates that monitoring SV hemostatic variables does not necessarily provide an accurate assessment of hemostatic function in regional vascular beds. Large-colon ischemia with or without reperfusion did not alter hemostatic function.

Twenty newborn Holstein calves were allotted at random to 4 groups: group A received 0.9% sterile saline solution; group B received phenylbutazone (5 mg/kg of body weight, IV) and 0.9% sterile saline solution; group C received progressively increasing doses of endotoxin (0.1 to 15 micrograms/kg); and group D received phenylbutazone and endotoxin similarly as did calves of groups B and C, respectively. Phenylbutazone was given once daily and saline solution or endotoxin were given every 8 hours for 5 days. Clinical variables-PCV, plasma total protein and fibrinogen concentrations, platelet count, prothrombin time, activated partial thromboplastin time, and fibrin degradation products concentration were measured at 24-hour intervals. Necropsy was performed on each calf. Phenylbutazone suppressed the clinical response to endotoxin challenge until large doses (7.5 to 15 micrograms/kg) were administered. Calves of groups C and D remained stable until they abruptly developed severe dyspnea necessitating euthanasia. Thrombocytopenia and leukopenia developed after the initial endotoxin dose. Prothrombin time was prolonged and PCV suddenly decreased at 96 hours. Necropsy revealed consistent lesions in the vascular endothelium and lungs. Phenylbutazone administration did not enhance or ameliorate endotoxin-induced hemostatic alterations or pathologic lesions.

We investigated changes in hemostatic function after infusion of 6% dextran 70 (high molecular weight dextran) at 2 rates. Six healthy dogs underwent 3 regimens: 20 ml of dextran/kg of body weight administered in 1 hour (trial A), 20 ml of dextran/kg administered in 30 minutes (trial B), and 0.9% sodium chloride solution as a control administered over 1 hour to achieve hemodilution equivalent to that for 20 ml of dextran/kg (trial C). Before and at 2, 4, 8, and 24 hours after the start of trials A and B, we measured PCV, total solids (TS) concentration, amount of von Willebrand factor antigen (vWF-Ag), factor VIII coagulant activity (VIII:C), prothrombin time, activated partial thromboplastin time (APTT), platelet retention in a glass bead column, and buccal mucosa bleeding time (BMBT). Values were not obtained at 8 and 24 hours for trial C. Saline-induced changes in hemostasis were significant (P < 0.05) from baseline throughout the sample collection period. Significant differences (P < 0.05) between trial A and control were observed for vWF:Ag, VIII:C, BMBT, APTT, TS, and PCV values at 2 hours, and for VIII:C at 4 hours. Significant differences (P < 0.05) between trial B and control were observed for APTT, TS, and PCV values at 2 hours, and for vwf-ag, VIII:C, BMBT, APTT, TS, and PCV values at 4 hours. During trials A and B, mean values of analytes infrequently deviated from reference intervals, and clinical signs of bleeding were not observed in any dog. Data for the dextran infusions paralleled each other and had a tendency to normalize, infrequently reaching baseline by 24 hours. Differences in overall hemostatic function were not detected between dextran infusions. Dextran 70 +/- a dosage of 20 ml/kg induces minimal hemostatic abnormalities when infused over 30 or 60 minutes to clinically normal dogs, but may precipitate bleeding in dogs with marginal hemostatic function.

Protein C content and plasminogen activity were measured in plasma from 100 horses with signs of colic. Data were analyzed by grouping horses 4 ways. Each horse was allotted to 1 of 2 outcome groups (survivors and nonsurvivors), 1 of 3 broad-category diagnosis groups (inflammatory disorders, strangulating obstructions, and all other gastrointestinal disorders), and 1 of 2 clinical management groups (medical and surgical). In a fourth grouping, all horses (although numbers of horses included in each subgroup were small) were assigned either to specific diagnostic groups that had high expectation for activated hemostasis (intestinal ischemia, endotoxemia, jugular thrombosis, peritoneal adhesions, and laminitis) or to a control group, in which active hemostasis was unlikely. Within 2 to 24 hours after admission, nonsurvivors developed lower protein C content than did survivors. Protein C content and plasminogen activity became low during hospitalization in horses with strangulating obstructions and in horses having surgery. The results from the grouping by specific diagnosis must be considered pilot data because the numbers of horses in each subgroup were small. Although not statistically significant, trends were noticed in protein C and plasminogen: (1) horses with intestinal ischemia and endotoxemia developed low protein C content and plasminogen activity, (2) protein C content became low in horses that developed peritoneal adhesions or laminitis, and (3) plasminogen activity became low in horses that developed jugular thrombosis. Low protein C content or low plasminogen activity, or both, may be useful as predictors for outcome and for these specific complications of equine colic. Protein C content and plasminogen activity were often normal at admission, but decreased by 2 to 24 hours; therefore, the hemostatic alterations appear to be an effect, rather than a cause of the gastrointestinal disorders. A return to normal values over several days may signify clinical improvement.

The balance of coagulation and fibrinolysis was studied in 15 horses during the prodromal stages of acute laminitis induced by carbohydrate overload. Progression of the disease was stopped 12 to 24 hours before the expected onset of lameness in trial 1 (8 horses) and at the onset of lameness in trial 2 (7 horses). The end points in each trial were identified by specific changes in blood pressures (trial 1) and by changes in pulse, rectal temperature, and arterial pressure (trial 2) that were anticipated on the basis of original description of the experimental model. Blood samples for hemostasis evaluation were collected before and after carbohydrate overload in trial 1 and after carbohydrate overload in trial 2. Significant changes were not detected in platelet count, mean platelet volume, prothrombin time, activated partial thromboplastin time, fibrinogen concentration, plasminogen concentration, alpha-2-antiplasmin, antithrombin III, protein C, thromboxane B2, or fibrin(ogen) degradation product concentration. We concluded that an imbalance in coagulation and fibrinolysis is not pathogenic in the onset of experimentally induced equine acute laminitis. Because several test methods used to evaluate hemostasis in these horses were new, reference values for 34 healthy adult horses were established.

Fetal and neonatal lamb hemostasis were studied from the 60th day of pregnancy to birth. Platelet counts and blood coagulation, as assessed by tests such as recalcification time and thromboelastography, were similar in fetuses, neonates, and adult sheep. The values of coagulation factors were low, ie, vitamin K-dependent Factors II, VII, IX, and X remained unchanged (30 and 40% of adult reference values) until the last 10 days of gestation, and then increased until birth (40 to 60%). Values of fibrinogen and Factor V followed a similar pattern, although their activities became identical to adult values at birth. Also, we measured values of protein C and antithrombin III, which are synthesized by the liver. The importance of hepatic failure and fetal vitamin K deficiency were discussed. Factors VIII and XII activities increased gradually during pregnancy to reach adult values at birth. Fetal fibrinolytic activity increased. This could not be explained by the values or tissue-type plasminogen activator (it was not detectable) or by the presence of its fast-acting inhibitor, whose concentration did not decrease.

Sepsis is associated with substantial morbidity and mortality in dogs. Alterations in hemostasis by systemic inflammation play an important role in the pathophysiology of sepsis. To evaluate the functional hemostatic changes in sepsis, we evaluated coagulation profiles and flow cytometric measurement of P-selectin (CD62P) expression on platelets, as well as platelet-leukocyte aggregation from a lipopolysaccharide (LPS)-induced endotoxemia model in dogs (n = 7). A sublethal dose of LPS [1 mg/kg body weight (BW)] induced thrombocytopenia and increased activated partial thromboplastin time (aPTT), prothrombin time (PT), and D-dimer concentrations. Flow cytometry analysis showed a significant increase in P-selectin expression on platelets between 1 and 24 h of a total 48 h of the experiment. In addition, platelet-leukocyte aggregation was significantly increased in the early stage of endotoxemia (at 1 and <6 h for platelet-monocyte aggregation and at 3 h for platelet-neutrophil aggregation). Our results suggest that CD62P expression on platelets and platelet-leukocyte aggregation, as measured by flow cytometry, can be useful biomarkers of disseminated intravascular coagulation (DIC) in canine sepsis. These functional changes contribute to our understanding of the pathophysiology of hemostasis in endotoxemia.

Objective—To optimize the overall hemostasis potential (OHP) assay for use with canine platelet-poor plasma and determine reference intervals in healthy dogs. Animals—40 healthy dogs. Procedures—Blood was collected from the dogs into citrated tubes, and platlet-poor plasma was obtained. The OHP assay and standard coagulation assays (prothrombin time, activated partial thromboplastin time, and fibrinogen concentration) were performed for each sample. The OHP assay outputs were tested for correlations with results of the standard coagulation assays, age, and sex. Results—Modifications to the published methodology for the OHP assay were required for use with canine plasma, with less coagulation activator (thrombin) and more fibrinolysis activator (tissue plasminogen activator) than used with human plasma. Male dogs had a higher OHP than did females. High fibrinogen concentrations were associated with increases in maximum optical density, OHP, and overall coagulation potential, and reduced prothrombin time was associated with increases in maximum optical density, overall coagulation potential, OHP, and maximum slope. Conclusions and Clinical Relevance—Results supported the use of the OHP assay as an accessible, cost-effective global coagulation assay. Further research is required to determine its clinical application as an alternative to thromboelastography or thrombin generation assays.