Diagnostic Approach to Small Animal Bleeding Disorders

Coagulation Abnormalities in Dogs with Parvoviral Enteritis

Hemostatic alterations have been documented in dogs with canine parvoviral enteritis. This study's aims were to measure the standard coagulation parameters, and to assess the relationship between them and the clinical variables in dogs with canine parvoviral enteritis. Nine client-owned dogs with a canine parvoviral infection were included in a prospective, observational clinical study. Clinical score and coagulation status were assessed at admission. All nine dogs showed alterations of three or more standard coagulation variables. A correlation analysis evidenced a significantly high positive correlation between the activated partial thromboplastin time and clinical score. The present study concurs that dogs with canine parvoviral enteritis have coagulation disorders that are detectable by measuring the standard coagulation parameters.

Evaluation of the Effect of Storage Time on ROTEM S® Parameters in Healthy and Ill Dogs

Simple Summary

Bleeding disorders can cause life-threatening illness in dogs. The need for fast recognition and diagnosis of these conditions is therefore of the utmost importance to have a positive impact on the patients’ survival. In the past decade, the use of viscoelastic testing for rapid assessment of global haemostasis has gained popularity. However, the most reliable time for testing after blood collection has not been determined. For this reason, blood samples were taken from healthy client-/staff-owned dogs and repeated measurements were performed at three different time points (10 min, 30 min, and 70 min after blood collection). Additionally, a group of currently ill patients was included and Ex-TEM S measurements were performed at the same three timepoints. We found that there was a significant change of results over time, suggesting the need for time-specific reference intervals. Which of these time points reflects the “true” coagulation status of our patients currently remains unknown.

Abstract

Viscoelastic testing as a bedside test to assess global haemostasis has gained popularity in the past decade, with rotational thromboelastometry (ROTEM) and thromboelastography (TEG) being the two commonly used devices. TEG studies suggest analysis 30 min after blood sampling. However, the reproducibility of results over time for ROTEM analysis using lyophilized samples in dogs has not been established. In this study, we investigated the influence of time on viscoelastic testing, using 33 healthy staff-/client-owned dogs for blood sampling and repeated measurements of ROTEM tracings at three different time points after blood collection. Additionally, a group of 21 hospitalized patients with suspected coagulation disorders were included to investigate whether stability over time was comparable between healthy and ill dogs. We demonstrated a significant difference of ROTEM tracings over time, with a tendency towards hypocoagulability over time. These changes do have a clinical relevance as they exceed reference intervals and could therefore lead to erroneous conclusions about a patient’s coagulation status. Therefore, time-specific reference intervals are proposed and presented in this publication.

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.

Analysis of blood clotting with the total thrombus analysis system in healthy dogs

To date, coagulation tests are unable to reflect in vivo coagulation status in the same system, including platelet function, fibrin clot formation, and whole blood flow. The Total Thrombus Analysis System (T-TAS), which is a microfluidic assay that simulates conditions in vivo, measures whole blood flow at defined shear rates under conditions designed to assess platelet function (PL-chip) or coagulation and fibrin clot formation (AR-chip). The T-TAS records occlusion start time, occlusion time, and area under the curve. We evaluated this test in healthy control dogs. We also investigated the effect in vivo of acetylsalicylic acid (ASA), and the effect in vitro of an anticoagulation drug (dalteparin; low-molecular-weight heparin; LMWH). The CV of the AUC of both chips was good (CVs of 6.45% [PL] and 1.57% [AR]). The inhibition of platelet function by ASA was evident in the right-shift in the PL test pressure curve. The right-shift in the AR test pressure curves showed that the administration of LMWH inhibited both platelets and the coagulation cascade. The T-TAS may be useful in the evaluation of canine blood coagulation.

Coagulation testing: Comparison of portable (CoaguChek® XS) and automated coagulation analyzer in healthy cats

Background and Aim:

The CoaguChek^® XS (CCX) is a portable coagulation analyzer that is widely used to monitor prothrombin time (PT) in human patients taking oral anticoagulants. It can also be reliably used for screening dogs when PT is in the normal range. Efficacy of the portable CCX coagulation analyzer was evaluated for testing PT in healthy cats and the normal range was established.

Materials and Methods:

Blood samples of 82 cats were collected from the jugular vein and PT was measured using both the CCX and an automated coagulation analyzer (ACA). Spearman’s correlation was used to measure the strength and direction of association between the two analyzers, while limits of agreement were assessed utilizing Bland-Altman analysis.

Results:

Range of PT using the CCX was 10.1-14.1 s. Correlation between the two analyzers was moderate but significant (r=0.3465, p=0.0014). Mean difference between CCX-PT and ACA-PT was 1.624 s and standard deviation was 0.890 with 95.1% of the samples falling within the limits of agreement.

Conclusion:

The CCX is a portable, easy to use coagulation analyzer that requires a small volume of blood and gives results within 1 min. Results showed moderate correlation and good agreement with a standard automated laboratory analyzer. The CCX can be used for screening coagulation testing when PT is in the normal range for cats. However, testing accuracy of the CCX in abnormal PT cats should be further investigated before diagnostic coagulopathy applications.

A Novel Microchip Flow Chamber (Total Thrombus Analysis System) to Assess Canine Hemostasis

Hemorrhagic diseases are common in dogs. Current coagulation assays do not model all aspects of in vivo hemostasis and may not predict bleeding risk. The Total-Thrombus Analysis System (T-TAS) is a novel hemostasis assay system in which whole blood flows through microfluidic channels at defined shear rates to provide qualitative and quantitative evaluation of platelet function (PL-chip) and coagulation function (AR-chip). The present study evaluated the T-TAS in dogs with hereditary bleeding disorders and with acquired hemorrhagic syndromes (Group 1), and healthy controls (Group 2). Hereditary defects included von Willebrand's disease (VWD; n = 4), hemophilia A (n = 2), and canine Scott syndrome (n = 2). Acquired hemorrhagic disorders included neoplastic hemoperitoneum (n = 2) and acute hemorrhagic diarrhea syndrome (n = 1). Citrate anticoagulated samples were collected from diseased dogs (Group 1, n = 11) and controls (Group 2, n = 11) for coagulation screening tests, fibrinogen analyses, D-dimer concentration, antithrombin activity, von Willebrand Factor antigen, PFA-100 closure time (PFA-CT), and thromboelastography (TEG). Citrate and hirudin anticoagulated samples were used for T-TAS analyses at two shear rates. Qualitative thrombus formation in each chip was recorded using the T-TAS video camera. Numeric parameters, derived from the instrument software, included occlusion start time (OST; time to 10 kPa), occlusion time (OT; time to 60 kPa (PL-chip) or 80 kPa (AR-chip)), and area under the pressure curve (AUC). Correlations between continuous variables were evaluated by Spearman's rank. Continuous variables were compared between groups by Student's t-test or the Mann-Whitney U-test. Alpha was set at 0.05. In combined analyses of all dogs, significant correlations were identified between T-TAS variables, between the PFA-CT and PL-chip parameters and between TEG variables and AR-chip parameters. The prothrombin time correlated with the AR-chip AUC at both shear rates. In Group 1 dogs, the AR-chip AUC at low shear was significantly reduced compared with Group 2 dogs. Aberrant thrombus formation was seen in video images recorded from dogs with VWD and hemophilia A. The T-TAS AR-chip analysis distinguished dogs with bleeding risk compared to healthy controls. Initial evaluations of the T-TAS suggest it may aid characterization of hemostasis in patients at-risk of bleeding and assist with delineating bleeding phenotypes.

Retrospective characterization of canine coagulopathies using the turbidimetric ACL-TOP 300 analyzer (2014-2015): Forty-seven dogs

OBJECTIVE

To characterize disseminated intravascular coagulation (DIC), liver failure (LF), post-hepatic cholestasis (PHC), and anticoagulant rodenticide intoxication (ROD) in dogs using an immunoturbidimetric coagulation analyzer and to characterize the relationship between clinical bleeding and bleeding parameters.

DESIGN

Retrospective study (August 2014-July 2015).

SETTING

University teaching hospital.

ANIMALS

Forty-seven client-owned dogs diagnosed with DIC (n = 24), LF (n = 9), PHC (n = 5), or ROD (n = 9) based on history, clinical pathology, cytology, histopathology. or exploratory surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Median prothrombin time (PT), activated partial thromboplastin time (aPTT), and quantitative fribrinogen assay (QFA) were above the reference interval for DIC, LF, PHC and ROD with the exception of a normal QFA for LF. Clot curve analysis for DIC was characterized by elevated PT Delta, PT first derivative, and aPTT Delta, and normal for aPTT second derivative; all LF parameters were within the RI; all PHC parameters were above the RI; and ROD had elevated aPTT delta, but low aPTT second derivative. Coagulopathic bleeding recognized within the DIC group was characterized by median PT delta in mABS (milliabsorbance), first derivative and aPTT delta values in mABS within the RI at 35.0, 55.5 and 38, respectively. The nonbleeding DIC group median values of these same parameters were 189.5, 586.5 and 288, respectively.

CONCLUSIONS

The classically utilized indicators of secondary hemostasis, PT and aPTT, were prolonged within all 4 groups; DIC, LF, PHC and ROD as expected. Fibrinogen concentration was increased in both PHC and ROD, decreased in LF and increased but with a bimodal distribution in DIC that correlated with clinical bleeding. The degree of PT and aPTT prolongation did not correlate with clinical bleeding in the DIC group, however clot curve analysis, did reveal an association.

Differing mechanisms of thrombin generation in live haematological and solid cancer cells determined by calibrated automated thrombography

: Calibrated automated thrombography (CAT) is emerging as a reliable tool for real-time estimation of thrombin generation potential. There is a clinical need for knowledge about the pathways underlying the thrombotic phenotype of different malignancies. Cells from solid (e.g. pancreatic cancer; n = 7) and malignant haematological cell lines (e.g. multiple myeloma; n = 5) were evaluated for thrombin generation, using CAT, with the addition of control plasma (NormTrol; Helena Biosciences, Gateshead, UK)) or plasma deficient in coagulation factors VII and XII. In addition, tissue factor (TF) cell surface expression was determined by flow cytometry. In platelet-free plasma, thrombin generation in all cancer cell lines was cell concentration dependent, with the pancreatic cancer line CFPAC-1 producing the highest thrombin of 220 nmol/l at 5 × 10-cells/ml concentration. Lag times and times to peak reflected most significant differences out of all thrombin generation parameters measured and were inversely correlated with cell surface TF surface expression. Solid tumour cell lines had higher thrombin peaks, faster lag times, and a thrombin generation profile of overall greater magnitude than haematological cell lines. In the absence of factor VII in platelet-free plasma, thrombin generation in solid pancreatic cancer cell lines was significantly reduced unlike in haematological cell lines. However, in the absence of factor XII, thrombin generation was reduced more in haematological cells but had little or no effect on solid cell lines. The CAT assay identified characteristic differences in thrombin generation kinetics between solid tumour and haematological cancer cell lines, of which lag time and time to peak correlated with TF cell surface expression.

Performance characteristics of the turbidimetric ACL-TOP CTS 300 coagulation analyzer in dogs and cats

OBJECTIVE

To evaluate the technical performance of the turbidimetric ACL-TOP CTS 300 coagulation analyzer (IL) in dogs and cats and to create reference intervals for standard and novel parameters.

DESIGN

Coagulation testing results from dogs and cats generated by the IL were prospectively compared with another mechanical clot detection system. Precision was documented and reference intervals were created for prothrombin time, activated partial thromboplastin time, and Clauss fibrinogen and D-dimer values, as well as for the quantitative clot curve parameters (high and low amplitude, delta, and first and second derivative curves). Clot curve signatures containing common artifacts due to lipemia, hemolysis, or preactivation were demonstrated.

ANIMALS

Residual frozen plasma from 20 dogs and 10 cats was used for method comparison; prospectively recruited healthy dogs (n = 48) and cats (n = 45) were used for reference interval and precision studies.

MEASUREMENTS AND MAIN RESULTS

Bland-Altman analysis showed a proportional positive bias in the IL compared with mechanical clot detection in dogs and a suggestion of a similar pattern in cats. Precision was good and met manufacturer's recommendations for all assays. Reference intervals are reported. Clot curve artifacts were similar in animals to those reported in people.

CONCLUSIONS

The turbidimetric system had a slight high proportional positive bias compared with mechanical clot detection. Thus, new reference intervals were generated including for novel parameters generated by clot curve analysis. Some preanalytical errors can be identified by inspection of clot curves. This robust novel technology compares favorably with mechanical endpoint detection methods and can be used in dogs and cats.

MRI Findings of Early-Stage Hyperacute Hemorrhage Causing Extramedullary Compression of the Cervical Spinal Cord in a Dog with Suspected Steroid-Responsive Meningitis-Arteritis

A 9-month-old female Weimaraner was presented to the emergency service due to episodes of fever and neck pain. Physical examination revealed a stiff neck posture and elevated body temperature. Shortly after clinical examination was performed, the dog developed peracute onset of non-ambulatory tetraparesis compatible with a C1–C5 spinal cord (SC) lesion. Immediately thereafter (<1 h), MRI of the cervical SC was performed with a 3-T scanner. A left ventrolateral intradural-extramedullary SC compression caused by a round-shaped structure at the level of C3––C4 was evidenced. The structure was iso- to slightly hyperintense in T1-weighted (T1W) sequences compared to SC parenchyma and hyperintense in T2-weighted, gradient echo, and fluid-attenuated inversion recovery. Moreover, the structure showed a strong homogeneous contrast uptake in T1W sequences. Cerebrospinal fluid (CSF) analysis revealed a mixed pleocytosis, as well as elevated protein and erythrocyte count. Early-stage hyperacute extramedullary hemorrhage was suspected due to immune mediated vasculitis. The dog was maintained under general anesthesia and artificial ventilation for 24 h and long-term therapy with corticosteroids and physiotherapy was initiated. Eight weeks after initial presentation, the dog was ambulatory, slightly tetraparetic. Follow-up MRI showed a regression of the round-shaped structure and pleocytosis was not evident in CSF analysis. This report describes an early-stage hyperacute extramedullary hemorrhage, a condition rarely recorded in dogs even in experimental settings.

Paraneoplastic hematological, biochemical, and hemostatic abnormalities in female dogs with mammary neoplasms

ABSTRACT: Paraneoplastic laboratory abnormalities are identified in several types of cancers in dogs and cats. In veterinary medicine, particularly in mammary cancer, there are few studies that correlate abnormal laboratory findings with tumor type and staging. The aim of this study was to evaluate hematological, biochemical, and hemostatic abnormalities and correlate them with mammary tumor staging in female dogs with mammary cancer. Blood samples from 24 female dogs were evaluated, and the hematological, biochemical, and hemostatic parameters were correlated with tumor staging obtained by physical examination, imaging exams, and histopathological surgical biopsies. The groups were organized according to tumor staging: group 1 (stages I and II), group 2 (stage III), and group 3 (stages IV and V). Anemia, neutrophilic leukocytosis, monocytosis, eosinophilia, thrombocytosis, hypoalbuminemia, hypocalcemia, hypoglycemia, and low blood urea were observed. The variables MCHC, TPP, and RDW were correlated with tumor staging with no clinical relevance. Thrombin time and fibrinogen were significant between the groups in the coagulation test, being associated with tumor staging. The findings suggest influence of the proinflammatory cytokines released during tumor growth.