ORIGINAL RESEARCH Evaluation of thrombelastographic platelet-mapping in healthy cats Shauna L. Blois 1 , Amrita Banerjee 1 , R. Darren Wood 2 Departments of 1 Clinical Studies and 2 Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada Key Words ADP, arachidonic acid, feline, hemostasis, TEG, thrombin Correspondence S.L. Blois, Department of Clinical Studies, Ontario Veterinary College, University of Guelph, 50 Stone Road, Guelph, Ontario N1G 2W1, Canada E-mail: sblois@uoguelph.ca DOI:10.1111/j.1939-165X.2012.00419.x Background: Thrombelastography (TEG) permits analysis of clot forma- tion but it is not specific for platelet activity. TEG PlateletMapping (TEG- PM) is a modification of TEG that uses adenosine diphosphate (ADP) and arachidonic acid (AA) as platelet agonists to define the contribution of platelets to clot formation. Objectives: The objectives of this study were to determine values for TEG- PM in healthy cats and the interassay variation of TEG-PM. Methods: TEG-PM analysis was performed on blood specimens collected from 12 healthy cats and was repeated using a second blood specimen col- lected 2 hours later. Maximum amplitudes generated by thrombin (MA thrombin ), fibrin (MA fibrin ), ADP-stimulated platelet activity (MA ADP ), and AA-stimulated platelet activity (MA AA ) were recorded. Results: Mean ± SD for MA thrombin was 51.1 ± 8.5 mm, for MA fibrin was 32.3 ± 17.7 mm, for MA ADP was 32.3 ± 15.0 mm, and for MA AA was 24.5 ± 12.2 mm. Mean MA ADP and MA fibrin were not significantly differ- ent, whereas mean MA AA was significantly lower than mean MA fibrin . Results from the first and second specimens were not significantly different. Correlation between the first and second specimens was moderate for MA thrombin , MA fibrin , and MA ADP , but was poor for MA AA . A high degree of variability (coefficient of variation 47.7–60.0%) was observed for MA fibrin , MA ADP , and MA AA . Conclusions: As MA ADP and MA AAAA were the same as or lower than MA fibrin , a valid baseline to determine platelet-stimulated clot formation could not be established. Considerable interassay variation and wide inter- vals for MA fibrin , MA ADP , and MA AA values in this study indicate that TEG-PM should be used cautiously in feline patients. Several preanalytical factors should be examined in further detail. Introduction Light transmission aggregometry and whole blood impedence aggregometry are standard platelet func- tion assays for feline blood samples. 1,2 However, aggre- gometry is labor-intensive and primarily used as a research tool. A point-of-care test that can detect both increased and decreased platelet function is needed in feline medicine. Thrombelastography (TEG) is becom- ing a widely utilized method of analyzing hemostasis in several animal species, including cats. 3,4 One limita- tion of TEG analysis is that it relies on thrombin to both activate platelets and generate a fibrin clot, and, there- fore, it is not specific for platelet activity. 5 Although TEG analysis may detect marked platelet dysfunction, thrombin activity can override mild to moderate inhi- bition of platelet activity resulting in a normal TEG tracing. 6,7 Thrombelastographic PlateletMapping (TEG-PM) is a modification of TEG that separately evaluates the contributions of thrombin, fibrin, and platelet activity to clot formation. 6 The TEG-PM assays use heparinized blood to negate the activity of thrombin and measure platelet reactivity in response to one of two platelet agonists, adenosine diphosphate (ADP) or arachidonic acid (AA). 6–8 TEG-PM is used in human medicine to Dr. Wood, an editor of the journal, was not involved in the peer- review process or in the decision to publish this article. Vet Clin Pathol 41/2 (2012) 223–227 ©2012 American Society for Veterinary Clinical Pathology 223 Veterinary Clinical Pathology ISSN 0275-6382