Thromboelastography: a tool for measuring hypercoagulability, hypocoagulability, and fibrinolysis

Objective: To describe the technique of thromboelastography (TEG) and review the applications of this coagulation test in humans and small animals. Data sources: Data sources included scientific reviews and original research publications. Human data synthesis: TEG in humans has been used for documentation of hypercoagulable and hypocoagulable states and has been shown to be beneficial in patient management. Veterinary data synthesis: Clinical evaluation of TEG in veterinary medicine is limited; however, recent reports have documented evidence of hypercoagulability in dogs with parvovirus and protein‐losing nephropathy. Additionally, many of the research models may be relevant to veterinary patients. Conclusions: TEG provides information about coagulation that is not available through routine coagulation tests. The application of TEG monitoring to veterinary patients shows promise; however, prospective clinical studies are needed.     

Application of thrombelastography/thromboelastometry to veterinary medicine

Thrombelastograph analyzers are point-of-care hemostatic analyzers that provide global assessment of the hemostatic process. Thrombelastography (TEG) detects and provides a continuous recording of the changes in the viscoelastic properties of whole blood from initial clot formation through fibinolysis. TEG has been validated for use in dogs, horses, and cats. Hemostasis research using TEG has focused on test validation, alterations of TEG tracings in animals with naturally occurring diseases, and the use of TEG for monitoring various therapeutic modalities. This article reviews TEG methodology and terminology, including potential sources of preanalytical and analytical errors, the correlation between TEG and other routine hemostatic assays, and current clinical applications of TEG, with emphasis on veterinary medical practice. Data suggest that TEG may be a sensitive and useful adjunctive tool for evaluating an animal with an underlying coagulopathy, including hypercoagulability and hypocoagulability. Additional prospective studies are needed to (1) correlate TEG tracing patterns with a clinical predisposition for bleeding or thrombosis in various disease states and (2) determine whether monitoring and treating hemostatic disorders based on TEG tracings improve clinical outcome.     

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.     

Making sense of blood gas results.

Recent technologic advances have allowed the production and marketing of cage-side blood gas analyzers to private practitioners. The widespread use of cage-side portable blood gas analyzers in veterinary practices has increased the need to develop the basic skills of blood gas analysis as part of a tool kit for practicing veterinarians. Rapid expansion of emergency and critical care medicine as a specialty and increased numbers of veterinary emergency and veterinary specialty practices have occurred concurrently with the availability of blood gas analyzers that are affordable for private practitioners. As a result, evaluation of blood gas results is no longer an activity confined to academic institutions and has become a daily part of many practicing veterinarians' activities.     

Advances in hematology analyzers

The complete blood count is one of the basic building blocks of the minimum database in veterinary medicine. Over the past 20 years, there has been a tremendous advancement in the technology of hematology analyzers and their availability to the general practitioner. There are 4 basic methodologies that can be used to generate data for a complete blood count: manual methods, quantitative buffy coat analysis, automated impedance analysis, and flow cytometric analysis. This article will review the principles of these methodologies, discuss some of their advantages and disadvantages, and describe some of the hematology analyzers that are available for the in-house veterinary laboratory.     

Systemic mastocytosis with subcutaneous hemorrhage and edema in a Greyhound dog: case report and review of diagnostic criteria

Systemic mastocytosis, characterized by infiltration of multiple organs by neoplastic mast cells, is a well-described entity in human medicine with specific criteria for diagnosis, but is ill defined in veterinary literature. Hemostatic disorders are reported in humans affected by systemic mastocytosis but have not been well described in veterinary literature. A 5-y-old, spayed female Greyhound dog had a 1-mo history of progressive ventral cutaneous edema, hemorrhage, and pain. Cytology of an antemortem aspirate from the subcutis of the ventral abdomen was suggestive of mast cell neoplasia, but no discrete mass was present. The dog was euthanized and submitted for autopsy; marked subcutaneous edema and hemorrhage were confirmed. The ventral abdominal panniculus and dermis superficial to the panniculus carnosus were infiltrated by a dense sheet of neoplastic mast cells. The neoplastic cells contained toluidine blue–positive granules and formed aggregates within the bone marrow and several visceral organs, including the liver, spleen, heart, and kidney. Diffuse edema and hemorrhage is an unusual presentation of mast cell tumors in dogs. Antemortem tests, including complete blood count, coagulation profile, and viscoelastic coagulation testing, were suggestive of a primary hemostatic defect. We discuss here the diagnostic criteria used in humans, how these can be applied to veterinary patients, and the limitations of the current diagnostic framework.     

Microarrays in veterinary diagnostics

Microarrays have numerous applications in the clinical setting, and these uses are not confined to the study of common human diseases. Indeed, the high-throughput technology affects clinical diagnostics in a variety of contexts, and this is reflected in the increasing use of microarray-based tools in the development of diagnostic and prognostic tests and in the identification of novel therapeutic targets. While much of the value of microarray-based experimentation has been derived from the study of human disease, there is equivalent potential for its role in veterinary medicine. Even though the resources devoted to the study of animal molecular diagnostics may be less than those available for human research, there is nonetheless a growing appreciation of the value of genome-wide information as it applies to animal disease. Therefore, this review focuses on the basics of microarray experimentation, and how this technology lends itself to a variety of diagnostic approaches in veterinary medicine.     

Coagulation disorders and liver disease

A definite association exists between hepatic disease and abnormalities of the coagulation system. These abnormalities can be detected by both routine and specialized coagulation tests. Extrahepatic causes of coagulation defects must first be ruled out by anamnesis, physical findings, and clinical laboratory tests before attributing the coagulopathies to hepatic disease. The routine use of coagulation tests to diagnose hepatic disease is not practical in veterinary medicine at the present time, but it can be a valuable adjunct to existing tests for hepatic disease and as a prognostic indicator during the course of treatment for established chronic disease.     

The role of tissue factor and tissue factor pathway inhibitor in health and disease states

Objective – To review the veterinary and human literature on the role of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in health and disease states.
Data Sources – Original research articles and scientific reviews from both human and veterinary literature were searched for relevance to TF and TFPI.
Human Data Synthesis – Interest in both TF and TFPI has grown widely over the last several years. The impact TF plays in coagulation, inflammation, angiogenesis, tumor metastasis, and cellular signaling has become apparent. Treatment with TFPI for severe sepsis has been examined and is still currently under investigation. Inhibition of the TF pathway is being studied as an aid in the treatment of neoplasia. The important physiologic and pathophysiologic role these molecules play has only begun to be understood.
Veterinary Data Synthesis – There is a paucity of publications that discuss the importance of TF and TFPI in veterinary medicine. An enhanced understanding of the TF pathway in human medicine, in experimental animal models treating sepsis with TFPI, and in animal models demonstrating the proangiogenic properties of TF provides relevance to veterinary medicine.
Conclusion – It is apparent that TF and TFPI are important in health and disease. An enhanced understanding of the physiologic and pathophysiologic roles of these factors provides better insight into coagulation, inflammation, angiogenesis, disseminated intravascular coagulation, and tumor metastasis. This greater understanding may provide for the development of therapeutics for sepsis, disseminated intravascular coagulation, and neoplasia.     

Application of flow cytometric techniques to veterinary clinical hematology

Flow cytometry has emerged as a major new technology in veterinary clinical laboratories. Flow cytometers in current use include stand-alone instruments and cytometers incorporated into hematology analyzers. Flow cytometers offer rapid and quantitative analysis of a variety of cell types based on cell size, molecular complexity, and antigenic composition. Therefore, flow cytometry complements and extends the knowledge that can be obtained by light microscopy. Stand-alone instruments are very flexible, however, this flexibility opens the instrument to obtaining invalid or misleading results. The recent development of monoclonal antibodies specific for epitopes on blood cells of food and companion animals has greatly expanded the spectrum of tests with potential clinical application. Tests that appear to have the greatest potential for routine application include reticulocyte and reticulated platelet enumeration, detection of erythrocyte-bound immunoglobulin, immunophenotyping of leukemias and lymphomas, and bone marrow differential cell counting. This report will briefly review the technical aspects of flow cytometry and then focus on techniques with present or potential application to the veterinary clinical laboratory.     

Use of a point-of-care beta-hydroxybutyrate sensor for detection of ketonemia in dogs

The urine test strip is the most common test used to detect ketones in veterinary patients, but it can underestimate the degree of ketonuria and hence, ketonemia. Additionally, adequate urine samples for analysis may be difficult to obtain from dehydrated animals. The standard method used to detect and monitor ketonemia in human medicine is measurement of serum or whole blood beta-hydroxybutyrate (βHOB). A point-of-care (POC) analyzer has been validated for this purpose in humans. This study compared the accuracy of the POC device to an enzymatic reaction laboratory method for measurement of βHOB in dogs. Although the POC sensor tended to overestimate βHOB concentrations, there was good correlation (R(2) = 0.96) and good agreement between the 2 methods with a bias +/- precision of 0.0860 +/- 0.3410 mmol/L βHOB. The POC βHOB sensor can be useful for assessing ketonemia in dogs.     

The Coombs' test in veterinary medicine: past, present, future

The Coombs' test, also known as the antiglobulin test, is used most frequently in veterinary medicine as an aid in the diagnosis of immune-mediated hemolytic anemia. The test also is used widely in human medicine to screen for red blood cell alloantibodies. Polyspecific reagents for veterinary use typically contain anti-IgG, anti-IgM, and anti-C3. Monospecific reagents also are available. False-positive and false-negative test results can be obtained. Inadequate sensitivity of the standard test in human and veterinary medicine has necessitated development of alternate, more sensitive technologies.     

Computerised decision support in veterinary medicine,exemplified in a canine idiopathic epilepsy care pathway

Computerised decision support is of emerging and increasing importance in human medicine, but as yet has not been thoroughly applied or evaluated in veterinary medicine. In this essay, the authors report on the first example of a veterinary care pathway, a specific form of computerised decision support, which guides clinicians through a clinical workflow and incorporates individual patient data to inform patient-specific decision recommendations. The veterinary care pathway was designed using consensus statements and specialist neurologist opinion to create a decision support tool concerning canine idiopathic epilepsy. The authors evaluated the care pathway by comparing 35 clinical decisions made by referral clinicians in historical cases of idiopathic epilepsy to decisions recommended by the care pathway when presented with the same clinical case. Their results show that in 77.1% (95% confidence interval [59.9, 89.6]) of cases the care pathway recommended a decision that was the same or similar to a specialist neurologist's decision. Whilst further studies are needed to explore the potential use of such technology in clinical practice, the authors believe this first application provides great promise of a new and alternative method of clinical decision support.     

The use of intravenous lipid emulsion as an antidote in veterinary toxicology

Objective – To review the use of IV lipid emulsion (ILE) for the treatment of toxicities related to fat‐soluble agents; evaluate current human and veterinary literature; and to provide proposed guidelines for the use of this emerging therapy in veterinary medicine and toxicology. Data Sources – Human and veterinary medical literature. Human Data Synthesis – Human data are composed mostly of case reports describing the response to treatment with ILE as variant from mild improvement to complete resolution of clinical signs, which is suspected to be due to the variability of lipid solubility of the drugs. The use of ILE therapy has been advocated as an antidote in cases of local anesthetic and other lipophilic drug toxicoses, particularly in the face of cardiopulmonary arrest and unsuccessful cardiopulmonary cerebral resuscitation. Veterinary Data Synthesis – The use of ILE therapy in veterinary medicine has recently been advocated by animal poison control centers for toxicoses associated with fat‐soluble agents, but there are only few clinical reports documenting successful use of this therapy. Evidence for the use of ILE in both human and veterinary medicine is composed primarily from experimental animal data. Conclusions – The use of ILE appears to be a safe therapy for the poisoned animal patient, but is warranted only with certain toxicoses. Adverse events associated with ILE in veterinary medicine are rare and anecdotal. Standard resuscitation protocols should be exhausted before considering this therapy and the potential side effects should be evaluated before administration of ILE as a potential antidote in cases of lipophilic drug toxicoses. Further research is waranted.     

An updated view of hemostasis: mechanisms of hemostatic dysfuntion associated with sepsis

Objective: To review the current understanding of mechanisms involved in normal hemostasis and to describe the changes associated with pro‐inflammatory disease processes such as sepsis. Data sources: Original research articles and scientific reviews. Human data synthesis: Organ damage caused by sepsis is created in part by the interdependent relationship between hemostasis and inflammation. Markers of coagulation have been found to have prognostic value in human patients with sepsis and there are both experimental and clinical investigations of the therapeutic potential of modulating the hemostatic system in sepsis. Improvement of 28‐day all‐cause mortality in severe sepsis by treatment with recombinant human activated Protein C strongly supports the interdependence of hemostasis and inflammation in the pathophysiology of sepsis. Veterinary data synthesis: Publications reporting clinical evaluation of the hemostatic changes occurring in septic dogs or cats are minimal. Experimental animal models of sepsis reveal significant similarity between human and animal sepsis and may provide relevance to clinical veterinary medicine until prospective clinical evaluations are published. Conclusions: It is now apparent that inflammation and the coagulation system are intimately connected. Understanding this relationship provides some insight into the pathogenesis of the hemostatic changes associated with sepsis. This new updated view of hemostasis may lead to the development of novel therapeutic approaches to sepsis and disseminated intravascular coagulation in veterinary medicine.     

西南部分地区中兽医验方收集分析与典型案例

中兽医是我国优秀的传统文化遗产,但随着近几年畜牧行业的发展和壮大,中兽医发展却遭遇瓶颈,传统经方验方传承面临困境。为了改善这种困境,使中兽医更好应用于临床,服务于社会,传承并发扬中兽医。本研究选用问卷调查法,交流访谈法及文献资料法对西南片区中兽医验方进行收集,并对其进行归纳整理、分析, 分析了验方来源地分布情况、验方使用时间情况、验方治疗病症情况及验方临床应用典型案例,可为中兽医发展及兽医临床医学提供参考。     

Effective use of simulations for the teaching and acquisition of veterinary professional and clinical skills

Simulation technology will feature prominently in this exciting, yet challenging, time for veterinary medicine. The profession is evolving to keep pace with rapid changes in clinical practice, scientific discovery, and educational strategy, while ensuring that it follows the public mandate to produce competent veterinarians. Among the challenges to meeting this educational goal are limitations-due to important issues such as animal welfare-on the availability of real patients for training. Drawing chiefly on the experience in human medicine, this article explores the use of simulations in veterinary medical education to provide safe and ethical alternative opportunities for learners to practice essential clinical and professional skills.     

Potential uses of recombinant human factor VIIa in veterinary medicine.

In human beings, rFVIIa has been used successfully to promote hemostasis in patients with various bleeding disorders. Patients with hemophilia, thrombocytopenia, and thrombocytopathy have been effectively and safely treated as well as patients with severe trauma or surgery resulting in profuse bleeding and patients with impaired liver function. Given these successes, the possibility of using rFVIIa in veterinary medicine is appealing. The clinical indications and uses in veterinary medicine would be similar, but there are currently two major obstacles: immunogenicity and cost. If these problems can be addressed, rFVIIa may become a valuable and indispensable therapy, especially in the emergency and critical care settings. The use of rFVIIa could allow for successful treatment of otherwise intractable bleeding as well as decrease the number of blood transfusions needed.     

The role of albumin replacement in the critically ill veterinary patient

Objective: To review the human and veterinary literature on the physiological role and effects of therapeutic albumin supplementation. Data sources: Data from human and veterinary literature was reviewed. Human data synthesis: Hypoalbuminemia often occurs in a variety of critical illnesses, and contributes to the development of life‐threatening complications, including pulmonary edema, delayed wound healing, feeding intolerance, hypercoaguability, and multiple organ dysfunction. Serum albumin concentration has been used as a prognostic indicator in cases of chronic hypoalbuminemia. The use of albumin replacement therapy in humans is sometimes controversial, but may be associated with improved morbidity and decreased mortality. Veterinary data synthesis: Unlike human literature, there is a paucity of controlled clinical studies in the literature regarding albumin supplementation in veterinary patients. Rather, the majority of published studies were performed in experimental animals or via retrospective analyses. One recent study evaluated the use of plasma to improve albumin concentration in dogs with hypoalbuminemia. Other older studies investigated wound healing in dogs with experimentally induced hypoalbuminemia. As in human medicine, serum albumin concentration may be helpful as a prognostic indicator in critically ill dogs. Conclusion: Albumin is one of the most important proteins in the body because of its role in maintenance of colloid oncotic pressure, substrate transport, buffering capacity, as a mediator of coagulation and wound healing, and free‐radical scavenging. Albumin replacement in veterinary medicine is difficult, but until prospective clinical trials determine the efficacy of albumin replacement are conducted, a suggested clinical guideline would be to maintain albumin concentration at or above 2.0 g/dl utilizing fresh frozen plasma.     

Building on existing models from human medical education to develop a communication curriculum in veterinary medicine

Communication is a core clinical skill of veterinary medicine and one that needs to be taught and learned to the same degree as other clinical skills. To provide this education and essential expertise, veterinary schools in many countries, especially including North America, the United Kingdom, and Australia, have begun to develop programs and communication curricula. Human medical education, however, has 30 years' experience in developing communication curricula, and is thus an excellent resource upon which veterinary educators can build and shape their own communication programs. This article describes a skills-based communication course that has been successfully implemented for veterinary medical education at Ontario Veterinary College (OVC) and was based on the University of Calgary Faculty of Medicine's well-established program. The Calgary-Cambridge Guides and supporting textbooks provide the scaffolding for teaching, learning, and evaluation in both programs. Resources such as space and materials to support the OVC program were also patterned after Calgary's program. Communication skills, and the methods for teaching and learning them, are equally applicable for the needs of both human medicine and veterinary medicine. The research evidence from human medicine is also very applicable for veterinary medicine and provides it the leverage it needs to move forward. With this extensive base available, veterinary medicine is in a position to move communication skills training forward rapidly.