Effects of exploratory laparotomy on plasma and peritoneal coagulation/fibrinolysis in horses

Plasma and peritoneal fluid samples were collected before and after surgery from 6 horses undergoing a ventral midline exploratory laparotomy and from 6 anesthetized control horses. Coagulation/fibrinolytic components measured in the plasma and peritoneal fluid of these horses included the functional activity of antithrombin III, alpha-2 antiplasmin, plasminogen, and protein C, and the concentrations of fibrinogen and fibrin degradation products. Peritoneal fluid antithrombin III, fibrin degradation products, and plasminogen values were significantly increased after surgery (over time) in principal horses. Compared with control horses, postoperative peritoneal fluid from horses undergoing laparotomy had significantly increased antithrombin-III activity at 12 and 72 hours, alpha-2 antiplasmin activity at 24 hours, fibrin degradation product concentrations at 6, 12, 24, 72, 96, and 144 hours, plasminogen activity at 6, 12, 24, 48, 72 and 96 hours, and protein-C activity at 12, 24, 72, and 96 hours. There were no significant changes in the peritoneal fibrinogen concentration in principal horses. Plasma plasminogen activity was significantly decreased at 24 hours after surgery in principal horses, compared with controls. Changes were minimal in the remaining plasma coagulation/fibrinolytic components of horses undergoing laparotomy. Plasma and peritoneal fluid values of anesthetized control horses did not change.     

Clotting profile in cattle showing chronic enzootic haematuria (CEH) and bladder neoplasms

Primary haemostasis (bleeding and blood clotting time), activated partial thromboplastin time (APTT), prothrombin time (PT), antithrombin III (ATIII), protein C, protein S, fibrinogen and D-dimer were determined in 13 cattle affected by chronic enzootic haematuria (CEH) and bladder neoplasms and 10 healthy cattle (control group). Increases in antithrombin III and protein S activities (P<0.01) and protein C and fibrinogen plasma levels (P<0.05) were observed in sick animals, while activated partial thromboplastin time, prothrombin time, and D-dimer did not show significant differences when compared to healthy animals. The clotting profile observed does not seem responsible for the chronic bleeding typical of CEH. The observed modification of some coagulation markers may derive from multiple interactions among cancer, inflammation and viral infection status typical of this syndrome.     

Acute thrombosis of limb arteries in horses with sepsis: five cases (1988-1998)

A hypercoagulable condition and poor perfusion to distal extremities might occur during equine endotoxaemic or septic shock, which could cause thrombosis of limb arteries. In our review, thrombosis occurred in neonatal foals in association with gram-negative bacteraemia. In 3 older foals and adults, thrombosis was associated with inflammatory bowel disease, diarrhoea and toxaemia. All patients had been treated with broad-spectrum antibiotics, nonsteroidal antiinflammatory drugs and i.v. crystalloid solutions. Two horses received i.v. hyperimmune plasma. A generalised coagulopathy was not suspected prior to clinical signs of distal limb necrosis, although thrombocytopenia occurred in 4 of the 5 cases at the time of, or shortly before, thrombosis. Thrombocytopenia, possibly due to platelets adherence to exposed subendothelial collagen, which induces contact activation of the intrinsic coagulation pathway, has been described in endotoxaemic horses and foals with gastrointestinal infectious or inflammatory diseases and disseminated intravascular coagulation. Activation of procoagulants by endotoxins, decreased blood flow to the limbs and endothelial damage, may have been responsible for a hypercoagulable condition leading to thrombosis in these 5 cases. The 3 enterocolitis patients may have had increased risk of thrombosis because of loss of antithrombin III, haemoconcentration and acidosis.     

Changes in the blood coagulation profile after ovariohysterectomy in female dogs

This study investigated changes in the coagulation profile of 10 healthy female dogs subjected to ovariohysterectomy. Blood samples were collected three times--before, directly after and 24 h after surgery. Plasma samples were analyzed to determine thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen content, D-dimer content and antithrombin (AT) III activity. The results revealed post-operative haemostatic system disorders related to prolonged APTT, higher fibrinogen and D-dimer concentrations and lower levels of AT III activity.     

Hemostatic abnormalities in equine colic

Hemostatic profiles were determined in 30 horses with clinical colic. Blood samples were obtained at the time of the animal's admission, and the following hemostatic tests were done: blood platelet count, plasma fibrinogen, plasma antithrombin, prothrombin time, partial thromboplastin time, thrombin time, protamine sulfate test for soluble fibrin monomer, and fibrin-fibrinogen degradation products. The patients were categorized in retrospect, according to the cause of the colic: group 1--colic associated with colitis and/or severe diarrhea, group 2--colic associated with torsion or obstruction of the intestine, and group 3--colic associated with impaction of the intestine or the presence of enteroliths. Of the 30 horses with colic, 28 had at least 1 abnormality in their coagulogram--the most frequent abnormalities being high plasma fibrinogen concentration, high circulating soluble fibrin monomer, or a long partial thromboplastin time or thrombin time. The horses in group 1 seemed to have the most severe coagulopathies, as indicated by the average number of demonstrable abnormalities. The horses in group 3 showed the fewest abnormalities--usually a high plasma concentrations of fibrinogen and/or soluble fibrin monomer. The results indicated that hemostatic abnormalities are not uncommon in horses with gastrointestinal disease and colic--the degree of severity depending to some extent on the cause of the colic.     

Changes in coagulation and markers of fibrinolysis in horses undergoing colic surgery

Activation of coagulation can be frequently found in horses with colic. However, it has also been demonstrated as a sequela of surgical trauma alone in humans. The purpose of the present study was to determine changes in coagulation and fibrinolysis in horses that underwent colic surgery and to evaluate whether these changes were secondary to the colic or the surgery and wound healing. Thirty horses that underwent colic surgery with uncomplicated recovery were included. Ten horses with a Forssell's procedure served as control group with a standardized surgical trauma. Besides daily physical examinations during the observation period of 10 days, activated partial thromboplastin time (aPTT), prothrombin time and thrombin time as well as fibrin monomer (FM), D-Dimer (DD) and antithrombin (AT) III were determined. Compared with the control group the aPTT was the only standard coagulation test that was significantly prolonged before and after the event of colic surgery. After surgery, hyperfibrinogenaemia occurred in all groups. In colic groups FM and DD concentrations were within reference range at admission,and were significantly greater than in control horses after surgery. AT III activity decreased after colic surgery, but did not change in the control group. It was concluded that an activated coagulation state after colic surgery has to be expected, resulting not only from the colic disease, but also from the event of surgery.     

Disseminated Intravascular Coagulation Associated with Colic in 23 Horses (1984–1989)

Disseminated intravascular coagulation (DIC) secondary to colic was diagnosed in 23 horses. Each horse was categorized retrospectively as to the cause of the colic based on surgical and/or necropsy findings: group 1 consisted of 14 horses with compromised intestine that required resection and anastomosis; group 2 consisted of 3 horses with nonstrangulating intestinal displacement and/or impactions; and group 3 consisted of 6 horses with colic associated with enteritis and/or colitis. Horses were considered to be affected with DIC if at least three of five hemostatic parameters were significantly abnormal: decreased antithrombin III (AT III) values, increased level of fibrin degradation products (FDP), thrombocytopenia, prolonged activated partial thromboplastin time, and prolonged prothrombin time. The most consistent hemostatic abnormalities were decreased AT III activity, increased FDP titers, and thrombocytopenia. Clotting times were more variable and did not always correlate with the presence of excessive hemorrhage. Excessive hemorrhage was present during surgery in seven horses and occurred within 1 to 12 hours after surgery in nine other horses. In addition to treatment of the primary disease, 19 horses received treatment for DIC consisting of heparin and/or plasma or fresh whole blood transfusions. Heparin alone was used in 12 horses. Heparin, in addition to fresh whole blood transfusions or fresh plasma, was administered to four horses. Three horses were treated with plasma alone. Four other horses were not treated specifically for the DIC. Eight horses (34%) survived the acute coagulopathy. Although a greater proportion of the surviving horses received heparin therapy (87.5%; 7/8) than did those that died (60%; 9/15), the difference was not statistically significant (P = 0.345).(ABSTRACT TRUNCATED AT 250 WORDS)     

Preoperative and postoperative hemostatic profiles of dogs undergoing ovariohysterectomy.

Hemostatic profiles were evaluated in 15 healthy dogs immediately before and 24 hours after celiotomy for routine ovariohysterectomy. Prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin degradation products, antithrombin III activity, platelet count, and hemogram were measured. There were no significant changes in prothrombin time, activated partial thromboplastin time, fibrin degradation products, antithrombin III activity, or platelet count. Fibrinogen concentration was significantly higher following surgery. Postoperative leukocyte differential counts were typical of stress leukograms, and were characterized by leukocytosis, neutrophilia, lymphopenia and eosinopenia. Mild decreases in packed cell volume, red blood cell count and hemoglobin concentration were consistent with minor blood loss during surgery or fluid retention and hemodilution postoperatively. It was concluded that celiotomy and routine ovariohysterectomy in healthy dogs did not alter hemostatic profiles 24 hours after surgery. Abnormal postoperative hemostatic profiles should not be attributed to surgery alone; other causes of abnormal hemostatic profiles should be investigated.     

Abnormal Hemostatic Profiles and Gastric Necrosis in Canine Gastric Dilatation-Volvulus

Hemostatic profiles (prothrombin time, activated partial thromboplastin time, fibrinogen concentration, fibrin degradation product concentration, platelet count, and antithrombin III activity) were acquired prospectively in 20 dogs with a diagnosis of gastric dilatation-volvulus. Eighteen dogs had abnormal results of one or more hemostatic test, including eight dogs that had hemostatic profiles consistent with a diagnosis of disseminated intravascular coagulation. During surgery, or at necropsy, the dogs' stomachs were evaluated for gross abnormalities, and lesions were graded subjectively as mild, moderate, or severe. Eight dogs had mild gastric lesions, five had moderate lesions, and seven had severe changes indicating gastric necrosis. Seventy percent (7/10) of the dogs with two to six abnormal hemostatic test results had gastric necrosis, whereas none of the 10 dogs with no or one abnormality had gastric necrosis (p < .001). A multiple linear regression equation, based on fibrin degradation product concentration, activated partial thromboplastin time, and antithrombin III activity was derived to predict gastric necrosis. This equation correctly identified gastric necrosis with 86% sensitivity, 100% specificity, 100% positive predictive value, and 93% negative predictive value.     

Acute haemostatic changes in accidentally traumatised dogs

Alterations of the haemostatic system were studied in 30 dogs within 24 h following natural injury. No other exclusion criteria were considered. Most dogs had bone fractures, thoracic and/or abdominal trauma. Compared to the controls, the platelet count and activities of all individual coagulation factors, inhibitors of the blood coagulation system (antithrombin, protein C) and plasminogen were significantly decreased (P < 0.01). The only exceptions were alpha2-plasmin inhibitor activity, which did not differ from the control group (P > 0.05), and an increased fibrinogen concentration (P = 0.0113). Deficiencies in the coagulation system were reflected by frequent abnormal results of the screening tests. In most of the animals, the concentrations of soluble fibrin and/or fibrin(ogen) degradation products were above the reference values (P < 0.0001). The absence of a decrease in fibrinogen and alpha2-plasmin inhibitor reflects their role as acute phase reactants. The results of this study indicate the high frequency of decompensated consumption of haemostatic components in acutely traumatised dogs.     

Thromboelastography in equine medicine: Technique and use in clinical research

Thromboelastography (TEG) is a viscoelastic, whole blood‐based assay that integrates information from both the cellular and soluble components of coagulation, providing a global evaluation of the haemostatic system. This contrasts with the conventional coagulation assays (i.e. platelet count, prothrombin time [PT], activated partial thromboplastin time [aPTT] and fibrinogen concentration [FIB]), which only provide information about one component (e.g. clotting factors in the case of PT and aPTT) of the haemostatic process, requiring the combination of several assays for a complete evaluation of haemostasis. Thromboelastography is an old technology that has been used in human medicine for over 50 years. However, it is relatively new in veterinary medicine and has only been applied to horses in the last 5 years. Clinical applications in human medicine include diagnosis and monitoring of coagulopathies. Currently, extensive research is being carried out to expand the use of TEG in dogs and cats. Therefore, it is expected that the use of this technique will also further expand in horses in the near future. To date, the available studies in the equine species have evaluated TEG in healthy horses, horses with gastrointestinal disease, septic foals, horses with exercise‐induced pulmonary haemorrhage (EIPH) and a filly with Glanzmann's thrombasthenia. The main objective of this review is to introduce the TEG technique to equine clinicians, providing information on how the TEG functions, blood sample collection and processing, variables measured and their interpretations, normal reference values and areas of potential clinical application.     

Hemostasis development in the lamb fetus and neonate

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 of tissue-type plasminogen activator (it was not detectable) or by the presence of its fast-acting inhibitor, whose concentration did not decrease.     

Prevalence of reduced fibrinogen binding to platelets in a population of Thoroughbreds

OBJECTIVE: To measure the frequency and magnitude of reduced fibrinogen binding in a population of horses from a Thoroughbred breeding farm. ANIMALS: 444 Thoroughbred horses, 1 to 27 years old, including 316 females, 72 geldings, and 56 sexually intact males. PROCEDURES: Blood was collected from horses into tubes containingacid citrate dextrose adenine, and washed platelets were examined by use of flow cytometry for their ability to bind fibrinogen. RESULTS: Data regarding fibrinogen binding to activated platelets were normally distributed, with nearly identical amounts of variation regardless of sex. In 3 horses, fibrinogen binding to platelets was reduced from 67.6% to 83.4%, compared with normal platelets, which indicated an inability of platelets to aggregate in response to thrombin (0.1 U/mL). CONCLUSIONS AND CLINICAL RELEVANCE: Platelet fibrinogen binding of the affected horses identified in this study was characteristic of a reported heritable bleeding disorder in which the reduction in fibrinogen binding correlated with prolonged bleeding times in template bleeding assays. The bleeding disorder is distinct from Glanzmann thrombasthenia, in which platelets fail to bind fibrinogen because of lack of alphallb-beta3 integrin on their surface. The prevalence of affected horses within the small sample population studied here (0.7% [n = 3]) is considerably higher than the prevalence of bleeding disorders within more genetically diverse groups.     

Use of clinical pathology in evaluation of horses with colic

Clinical pathology is a valuable adjunct to physical examination of cases of colic. The present review considers evaluation of cases of colic for three main purposes: (1) making a prognosis, (2) deciding whether to operate, and (3) making a diagnosis. Blood tests noted to be useful for prognostication were hematocrit, lactate and urea nitrogen concentrations, pH, anion gap, fibrin/fibrinogen degradation products, antithrombin III activity, prothrombin time, and thrombin time. Horses with a poor prognosis often have relative polycythemia, marked lactic acidosis, high anion gap, azotemia, and coagulation abnormalities evidenced by increased fibrin/fibrinogen degradation products, decreased antithrombin III activity, and prolonged prothrombin and thrombin times. The decision to operate is usually a clinical one, supported by relative polycythemia, hyperglycemia, and, possibly, abnormal peritoneal fluid analysis. Diagnosis of the primary problem (causing the colicky signs) is also often based largely on physical examination. However, peritoneal fluid analysis provides worthwhile data, especially in cases of peritonitis or intestinal ischemia and infarction.     

Diagnosis of disseminated intravascular coagulation in dogs admitted to an intensive care unit.

OBJECTIVE: To describe and evaluate hemostatic function in critically ill dogs with clinical signs of diseases that predispose to disseminated intravascular coagulation (DIC). DESIGN: Prospective case series. ANIMALS: 59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs (control dogs). PROCEDURE: Activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin clotting time (TCT), plasma fibrinogen concentration, serum concentration of fibrin and fibrinogen-related antigens (FRA), and plasma antithrombin III (AT III) activity were determined for all dogs. Results from affected dogs were compared with those of control dogs. In some affected dogs, postmortem tissue specimens were examined for evidence of microvascular thrombosis. A diagnosis of DIC was made by fulfilling at least 3 of the following criteria: 1) abnormal aPTT, PT, or TCT value, 2) low plasma fibrinogen concentration, 3) low plasma AT III activity, 4) high serum FRA concentration, or 5) low platelet count. To evaluate the severity of hemostatic dysfunction, 3 arbitrary categories (mild, moderate, and severe) were proposed. RESULTS: A diagnostic strategy based on moderate hemostatic dysfunction identified DIC in 16 of 59 (27.1%) affected dogs. The AT III activity was < 70% in 15 of 16 dogs with DIC. Microvascular thrombosis was observed in tissue specimens from 7 of 8 affected dogs. Serum FRA and plasma fibrinogen concentrations did not contribute in establishing a diagnosis of DIC. CONCLUSIONS AND CLINICAL RELEVANCE: A diagnosis of DIC can be made when hemostatic dysfunction is moderate in dogs with clinical signs of diseases associated with DIC.     

An overview of hemostasis

The normal hemostatic system is complex yet exquisitely well regulated. Interrelationships exist between responses of the vasculature, circulating platelets, coagulation proteins, and fibrinolytic mechanism. These relationships serve to limit blood loss, preserve tissue perfusion, and stimulate local repair processes. Natural inhibitors of coagulation and fibrinolysis modulate these systems to prevent uncontrolled thrombosis or hemorrhage following pathologic stimuli. Vascular endothelial cells play an important role in the maintenance of a thromboresistant luminal interface with circulating cells and proteins. Normal hemostasis also requires the synthetic, metabolic, and repair processes of the vascular endothelium. The initial vascular response to injury produces brief vasoconstriction and exposes subendothelial substances that attract circulating platelets and activate coagulation proteins. Platelets respond by adherence and aggregation at the site of injury, with subsequent release of substances that mitigate blood loss. Platelet adherence to collagen requires von Willebrand's factor, fibrinogen, fibronectin, and specific glycoprotein receptors on platelet surfaces. Platelet-to-platelet interactions (aggregation) recruit additional platelets to the primary hemostatic plug. Aggregation requires fibrinogen, energy, and calcium. Release of ADP, serotonin, and the contents of intracellular granules as well as generation of prostaglandins prepares platelet surfaces for reactions with the coagulation proteins. Activation of the intrinsic or extrinsic coagulation pathway, or of both, causes formation of fibrin from fibrinogen by means of an elaborate and intricate system that also entraps platelets and activated coagulation proteins. The intrinsic system is activated by the contact of factor XII with a negatively charged surface, most likely collagen. Through a series of reactions with prekallikrein, HMWK, and factors XI, IX, and VIII, the common coagulation pathway is propagated. The extrinsic, or tissue factor, system stimulates both the common pathway and factor IX the intrinsic pathway. Discovery of this stimulation of the intrinsic pathway by factor VII in the extrinsic pathway has stimulated reassessment of the biologic importance of the extrinsic system. The common pathway includes factors X and V and causes thrombin to convert fibrinogen to fibrin. Calcium and platelet phospholipids are substances that have important roles in steps in the coagulation scheme. Once fibrin is formed, factor XIII interacts with the substance, providing a stabilizing effect.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hemostatic alterations in pigs fed sublethal doses of Sarcocystis miescheriana

Effects of non-lethal Sarcocystis miescheriana infections on the blood coagulation system were investigated. Nine pigs were inoculated orally with 2 X 10(5) sporocysts (Group A) and nine pigs (Group B) served as non-infected controls. Blood samples were taken from the vena jugularis externa every 2 or 3 days until 19 days post-infection (dpi). The following parameters were investigated: partial thromboplastin time (PTT), prothrombin time (PT), thrombin time (TT), thrombin coagulase time (TCT), fibrinogen (FIB), factor (F) VIII, F XI, F XII, antithrombin III (AT III), alpha 2 macroglobulin (alpha 2 MG), alpha 2 antiplasmin (alpha 2 AP), pre-kallikrein (PK), and the number of circulating thrombocytes. All infected pigs suffered from acute sarcocystiosis between 12 and 19 dpi. Clinical illness was most severe from 14 to 17 dpi. At this time, PTT and FIB increased, and TT and TCT decreased slightly. The activities of the clotting factors increased at 17 and 19 dpi. However, only F VIII activity was significantly higher in the infected pigs than in the controls at 17 and 19 dpi. PK was significantly lower in the infected pigs at 12, 14, and 17 dpi. Thrombocyte counts were reduced with the onset of the acute phase of illness and some pigs had marked thrombocytopenia. These results indicate low-grade disseminated intravascular coagulation (DIC) in the course of mild S. miescheriana infections in pigs.     

An evaluation of the Abaxis VSPro for the measurement of equine plasma fibrinogen concentrations

Reasons for performing study: Accurate measurement of plasma fibrinogen concentrations is an important tool for assessment of horses with inflammatory diseases. Objectives: To determine the precision and accuracy of a benchtop instrument using both fresh and frozen equine plasma by comparing the plasma fibrinogen concentration measured by a benchtop instrument to 2 separate laboratory standard methods (ACL 100 and STA Compact) for fibrinogen measurement. Methods: Accuracy and precision of the VSPro was evaluated using both human fibrinogen standards and samples from horses. Fifty frozen samples from horses with gastrointestinal disease had the fibrinogen concentration measured using the ACL 1000 and the VSPro. Fifty fresh samples were collected from hospitalised horses and fibrinogen concentration was measured using the STA Compact coagulation machine and the VSPro. Correlations for measurements were performed, as well as Bland‐Altman analysis. Results: Coefficients of variability for the VSPro ranged from 7% to 15%. The VSPro fibrinogen values were well correlated to both the ACL 1000 (r = 0.94, P<0.001) and the STA Compact measurements (r = 0.926, P<0.001). Bland‐Altman analysis showed a mean bias of ‐0.83 g/l (95% confidence interval ‐2.03–0.324 g/l) for the ACL 1000 and a mean bias of ‐0.024 g/l (95% confidence interval ‐1.434–1.386 g/l) for the STA Compact. Conclusions: The VSPro appears to have adequate accuracy and precision for clinical measurement of plasma fibrinogen concentrations. Potential relevance: The VSPro provides a measurement of equine plasma fibrinogen concentration using a benchtop instrument with a rapid test time that has comparable accuracy to the fibrinogen concentration obtained from reference laboratories.     

Comparative analysis of haematological, haemostatic, and inflammatory parameters in canine venous and arterial blood samples

The objective of the present study was to validate the use of blood collected from an indwelling arterial catheter for analysis of haematological, coagulation and inflammatory parameters in canines compared to venous blood collected directly from the jugular vein. Blood samples were collected from 11 dogs. Agreement between sampling methods was found for neutrophil and monocyte counts, prothrombin time, activated partial thromboplastin time, antithrombin, protein C, factor VIII and C-reactive protein, whereas a statistically significant difference was found for white blood cells, lymphocyte, erythrocyte and platelet counts, haemoglobin, haematocrit, fibrinogen and thrombin time (TT). In conclusion, it is necessary to be aware that results from a complete blood count obtained from canine venous and arterial blood samples may not be comparable. Values for haemostatic parameters from arterial and venous blood samples, with the exception of fibrinogen and TT, were however statistically identical.