Clara B. Marschner

At veterinary university hospitals, clinical teachers have two responsibilities: treating patients and teaching students. At the University of Copenhagen, many teachers are involved in the clinical teaching and assessment of veterinary students, but only some of these teachers—the academic faculty—have access to pedagogical training. We conceived an idea to develop a pedagogical program aimed specifically at clinical teachers. However, instead of implementing an existing program developed elsewhere, we decided to create a discipline-specific, context-relevant program. The creational process applied the principles of action learning consulting (ALC), which dictate that a pedagogical consultant and key involved employees cooperate closely in a dynamic, creational process. A program was developed with content focused on addressing the perceived needs expressed by the clinical teachers. The program consisted of three 2.5-hour seminars, each covering one of the main themes: teaching situations in clinical settings, pedagogical psychology in clinical teaching, and assessment and feedback. The seminars were conducted in the afternoon approximately 2 months apart and were facilitated by the two authors with a veterinary background (CBM, RL). Ten to 20 clinical teachers participated in each seminar, and feedback from participants was positive overall, acknowledging the creation of a forum for critical discussions on clinical teaching and learning and greater insight into pedagogical themes. As a result of the application of the ALC principle, the program is highly context relevant and has gained optimal anchorage within the organization; the seminars will therefore be repeated and allowed to continuously evolve.

Objective: To establish and compare the repeatability and reproducibility of activated thromboelastography (TEG) and thromboelastometry (ROTEM) assays.Design: Multicenter in vitro test standardization.Setting: Veterinary academic centers.Animals: Test samples were obtained from normal, healthy dogs. Sixty identical 5 mL aliquots of canine platelet‐rich plasma collected by apheresis, frozen in 6% dimethyl sulfoxide, were tested initially. Sixty identical 6 mL aliquots of canine fresh frozen plasma with admixed cryoprecipitate were subsequently evaluated.Interventions: None.Measurements and Main Results: Frozen study samples, quality controls, reagents, and consumables were distributed to participating centers (7 TEG and 3 ROTEM). TEG centers analyzed study samples with kaolin and tissue factor activated assays; ROTEM centers ran proprietary ellagic acid activated and tissue factor activated assays. All machines underwent quality control prior to sample analysis. Within‐ and between‐center coefficients of variation (CVs) were calculated and compared using Mann–Whitney tests and calculation of intraclass correlation coefficients. Within and between centers, individual parameters for both TEG and ROTEM assays were comparable. Both within‐center and between‐center CVs varied markedly (0.7–120.5% and 1.4–116.5%, respectively) with assay type, instrument, and parameter. CVs for equivalent parameters were not significantly different between the 2 platforms. Intraclass correlation coefficients suggested moderate agreement between centers. In general, individual parameter CVs for platelet‐rich plasma samples were lower in TEG centers, while CVs for canine fresh frozen plasma with admixed cryoprecipitate samples were lower in ROTEM centers.Conclusions: More variation within and between centers was identified than anticipated, but some parameters such as alpha angle were repeatable and reproducible. Sample types for future multicenter standardization efforts will require further optimization and may need to be adapted separately to each platform. Individual centers using viscoelastic tests for evaluation and management of clinical patients should take steps to minimize preanalytical and analytical sources of variation.

Objective: To investigate parameters causing canine thromboelastographic hypercoagulability and to investigate whether thromboelastography (TEG) with Cytochalasin D (Cyt D) added is related to parameters of platelet activity.Design: Prospective observational study on hemostatic and inflammatory parameters. Data were collected between November 2012 and July 2013.Setting: University teaching hospital.Animals: Twenty‐eight dogs suffering from diseases predisposing to thrombosis and 19 clinically healthy dogs. Diseased dogs were enrolled if they fulfilled inclusion criteria regarding age, size, informed client consent, and obtained a diagnosis of a disease that has been associated with thrombosis or hypercoagulability.Interventions: None.Measurements and Main Results: Parameters of coagulation and anticoagulation, fibrinolysis, and antifibrinolysis, platelet activity, inflammation, platelet count, and hematocrit were measured using CBC, TEG, platelet aggregation on multiplate, platelet activity on flow cytometry, and hemostatic and inflammatory markers on plasma and serum analyses. ANOVA and multilinear regression analyses indicated that especially hematocrit and the inflammatory parameters C‐reactive protein and interleukin‐8 showed best association with overall clot strength in diseased dogs with hypercoagulable TEG tracings. Ratios presumed to reflect platelet contribution to the TEG tracing obtained in TEG analyses with Cyt D were related especially with hematocrit and P‐selectin expression of platelets measured after γ‐Thrombin activation on flow cytometry.Conclusion: Overall clot strength in TEG analyses of the hypercoagulable dogs included in the present study appears to be primarily associated with inflammation as well as hematocrit. Furthermore, the ratio between standard TEG analyses and TEG analyses with Cyt D may reflect some degree of platelet activity.

Fractal analysis of canine pulmonary vessels could allow quantification of their space‐filling properties. Aims of this prospective, analytical, cross‐sectional study were to describe methods for reconstructing three dimensional pulmonary arterial vascular trees from computed tomographic pulmonary angiogram, applying fractal analyses of these vascular trees in dogs with and without diseases that are known to predispose to thromboembolism, and testing the hypothesis that diseased dogs would have a different fractal dimension than healthy dogs. A total of 34 dogs were sampled. Based on computed tomographic pulmonary angiograms findings, dogs were divided in three groups: diseased with pulmonary thromboembolism (n = 7), diseased but without pulmonary thromboembolism (n = 21), and healthy (n = 6). An observer who was aware of group status created three‐dimensional pulmonary artery vascular trees for each dog using a semiautomated segmentation technique. Vascular three‐dimensional reconstructions were then evaluated using fractal analysis. Fractal dimensions were analyzed, by group, using analysis of variance and principal component analysis. Fractal dimensions were significantly different among the three groups taken together (P = 0.001), but not between the diseased dogs alone (P = 0.203). The principal component analysis showed a tendency of separation between healthy control and diseased groups, but not between groups of dogs with and without pulmonary thromboembolism. Findings indicated that computed tomographic pulmonary angiogram images can be used to reconstruct three‐dimensional pulmonary arterial vascular trees in dogs and that fractal analysis of these three‐dimensional vascular trees is a feasible method for quantifying the spatial relationships of pulmonary arteries. These methods could be applied in further research studies on pulmonary and vascular diseases in dogs.

Diagnosis of pulmonary thromboembolism (PTE) in dogs relies on computed tomography pulmonary angiography (CTPA), but detailed interpretation of CTPA images is demanding for the radiologist and only large vessels may be evaluated. New approaches for better detection of smaller thrombi include dual energy computed tomography (DECT) as well as computer assisted diagnosis (CAD) techniques. The purpose of this study was to investigate the performance of quantitative texture analysis for detecting dogs with PTE using grey-level co-occurrence matrices (GLCM) and multivariate statistical classification analyses. CT images from healthy (n = 6) and diseased (n = 29) dogs with and without PTE confirmed on CTPA were segmented so that only tissue with CT numbers between −1024 and −250 Houndsfield Units (HU) was preserved. GLCM analysis and subsequent multivariate classification analyses were performed on texture parameters extracted from these images. Leave-one-dog-out cross validation and receiver operator characteristic (ROC) showed that the models generated from the texture analysis were able to predict healthy dogs with optimal levels of performance. Partial Least Square Discriminant Analysis (PLS-DA) obtained a sensitivity of 94% and a specificity of 96%, while Support Vector Machines (SVM) yielded a sensitivity of 99% and a specificity of 100%. The models, however, performed worse in classifying the type of disease in the diseased dog group: In diseased dogs with PTE sensitivities were 30% (PLS-DA) and 38% (SVM), and specificities were 80% (PLS-DA) and 89% (SVM). In diseased dogs without PTE the sensitivities of the models were 59% (PLS-DA) and 79% (SVM) and specificities were 79% (PLS-DA) and 82% (SVM). The results indicate that texture analysis of CTPA images using GLCM is an effective tool for distinguishing healthy from abnormal lung. Furthermore the texture of pulmonary parenchyma in dogs with PTE is altered, when compared to the texture of pulmonary parenchyma of healthy dogs. The models’ poorer performance in classifying dogs within the diseased group, may be related to the low number of dogs compared to texture variables, a lack of balanced number of dogs within each group or a real lack of difference in the texture features among the diseased dogs.

OBJECTIVE To investigate serum and plasma serotonin concentrations, percentage of serotonin-positive platelets, level of surface-bound platelet serotonin expression (mean fluorescence intensity [MFI]), and platelet activation (CD62 expression) in platelet-rich plasma from Cavalier King Charles Spaniels with myxomatous mitral valve disease (MMVD). ANIMALS Healthy dogs (n = 15) and dogs with mild MMVD (18), moderate-severe MMVD (19), or severe MMVD with congestive heart failure (CHF; 10). PROCEDURES Blood samples were collected from each dog. Serum and plasma serotonin concentrations were measured with an ELISA, and surface-bound platelet serotonin expression and platelet activation were determined by flow cytometry. RESULTS Dogs with mild MMVD had higher median serum (746 ng/mL) and plasma (33.3 ng/mL) serotonin concentrations, compared with MMVD-affected dogs with CHF (388 ng/mL and 9.9 ng/mL, respectively), but no other group differences were found. Among disease groups, no differences in surface-bound serotonin expression or platelet activation were found. Thrombocytopenic dogs had lower serum serotonin concentration (482 ng/mL) than nonthrombocytopenic dogs (731 ng/mL). In 26 dogs, a flow cytometry scatterplot subpopulation (FSSP) of platelets was identified; dogs with an FSSP had a higher percentage of serotonin-positive platelets (11.0%), higher level of surface-bound serotonin expression (MFI, 32,068), and higher platelet activation (MFI, 2,363) than did dogs without an FSSP (5.7%, 1,230, and 1,165, respectively). An FSSP was present in 93.8% of thrombocytopenic dogs and in 29.5% of nonthrombocytopenic dogs. CONCLUSIONS AND CLINICAL RELEVANCE A substantive influence of circulating serotonin on MMVD stages prior to CHF development in Cavalier King Charles Spaniels was not supported by the study findings. An FSSP of highly activated platelets with pronounced serotonin binding was strongly associated with thrombocytopenia but not MMVD.

Background: In people, studies have shown that resistance to fibrinolysis could be a contributing factor to thrombosis. Tissue‐plasminogen‐activated (t‐PA) thromboelastography (TEG) has been used to evaluate endogenous fibrinolytic potential. In dogs, TEG has been used for the diagnosis of various hemostatic disorders, but studies evaluating fibrinolysis are limited. Investigations into the potential of t‐PA‐modified TEG to monitor endogenous fibrinolytic potential are lacking in both healthy dogs and dogs with diseases predisposing to development of thrombosis.Objectives: The aim of this study was to compare 3 t‐PA‐modified TEG assays and compare the endogenous fibrinolytic potential in dogs suffering from diseases associated with thrombosis with a group of healthy dogs.Methods: Three different TEG assays, such as native, tissue factor‐activated, and kaolin‐activated, were modified with t‐PA and used to compare whole blood samples from 16 healthy control dogs and 20 diseased dogs.Results: Thromboelastography lysis variables were significantly affected by addition of t‐PA in all 3 assays. Lysis results in diseased dogs were comparable to those in healthy dogs prior to addition of t‐PA. After addition of t‐PA, lysis results were significantly decreased in the diseased group compared with healthy dogs. The lowest median lysis levels were found in dogs with systemic inflammation and protein‐losing disorders.Conclusion: Addition of t‐PA activates fibrinolysis in TEG of blood from both healthy dogs and dogs with diseases predisposing to thrombosis. The significantly decreased fibrinolysis in diseased dogs suggests that this may be a potential prothrombotic risk factor in dogs.

Objective To investigate the performance of the Multiplate platelet function analyzer with regards to: (1) the use of 3 different anticoagulants (ie, citrate, hirudin, and heparin) and (2) the evaluation of optimal assay time. Design Prospective observational in vitro study. Setting University veterinary teaching hospital. Animals Twenty clinically healthy dogs and 3 ill dogs. Interventions None. Measurements and Main Results A total of 184 analyses were performed with duplicate measurements in each test cell and results are reported as mean of the 2 measurements. Analyses were performed on blood samples from 20 dogs collected in citrate, hirudin, or heparin. A total of 4 analyses were performed on every blood sample using adenosine diphosphate, collagen, and arachidonic acid as agonists as well as a control with 0.9% sodium chloride (buffer). Aggregation in hirudin samples was significantly increased compared with heparin at all analysis times except at 6 minutes when using ADP as agonist; however, hirudin samples also demonstrated significant aggregation in the buffer control, compared to both citrate and heparin. Citrated samples yielded significantly lower aggregation compared with both hirudin- and heparin-stabilized samples at 6 and 12 minutes when ADP and collagen were used as agonists, and at most analysis times with arachidonic acid. The assay performed best at shorter analyses times, whereas longer analyses times yielded larger variation in data. Conclusions There was a good aggregation response and acceptable analytical variation in both heparin- and hirudin-anticoagulated samples with all tested agonist at the concentrations recommended by the manufacturer. The results suggest that heparin may be superior as anticoagulant for Multiplate analyses in dogs and that short analyses times are preferable. Spontaneous platelet autoaggregation in hirudin samples warrants careful evaluation of results using this anticoagulant, especially at longer test times. The use of citrate is discouraged for Multiplate analyses in dogs due to a weak aggregation response.

During the last decade, thromboelastography (TEG) has gained increasing acceptance as a diagnostic test in veterinary medicine for evaluation of haemostasis in dogs, however the use of TEG in cats has to date only been described in one previous study and a few abstracts. The objective of the present study was to evaluate and compare three different TEG assays in healthy cats, in order to establish which assay may be best suited for TEG analyses in cats.