Establishing a protocol for thromboelastography in sea turtles

Abstract

Thromboelastography (TEG) provides a global evaluation of haemostasis. This diagnostic test is widely used in mammals but has not previously been performed in reptiles, mainly due to the limited availability of taxon-specific reagents. The objective of this pilot study was to establish a protocol to perform TEG in sea turtles. Pooled citrated plasma, stored at −80°C, from four green turtles (Chelonia mydas) was assayed on a TEG 5000. Several initiators were evaluated: kaolin (n=2), RapidTEG (n=2), fresh (n=2) and frozen (n=6) thromboplastin extracted from pooled brain tissue from several chelonian species, human recombinant tissue factor at 1:100 (n=1), Reptilase (n=2), and rabbit thromboplastin (n=1). Both fresh and frozen chelonian thromboplastin were superior in producing quantifiable TEG reaction time compared with all other reagents. These findings are consistent with the lack of an intrinsic pathway in turtles and confirmed a lack of coagulation in the turtle samples in response to mammalian thromboplastin. A TEG protocol was subsequently established for harvested species-specific frozen thromboplastin. The frozen thromboplastin reagent remained stable after one year of storage at −80°C. The developed protocol will be useful as a basis for future studies that aim to understand the pathophysiology of haemostatic disorders in various stranding conditions of sea turtles.

Coagulation testing in green iguanas (Iguana iguana) with development of prothrombin time assays using reptile and avian thromboplastin

“…5 However, in a recent study of sea turtles, rabbit-derived thromboplastin failed to produce a thromboelastographic trace after 85 minutes. 7 In green iguanas (Iguana iguana), PTs were markedly prolonged and variable using 5 different reagents, thrombin times, and dilute Russell's viper venom times (RVVT), or no clot formation occurred, which limited the clinical usefulness of the tests in this species. 8 The objective of this study was to evaluate the extrinsic and common coagulation pathways in green iguanas, using avian/reptile extrinsic pathway activators and commercially available coagulation screening test reagents, respectively.…”

“…In sea turtles, prothrombin time (PT) measured using a commercially available assay with mammalian thromboplastin produced times ranging from 21.1 to 65.8 seconds 5 . However, in a recent study of sea turtles, rabbit‐derived thromboplastin failed to produce a thromboelastographic trace after 85 minutes 7 . In green iguanas ( Iguana iguana ), PTs were markedly prolonged and variable using 5 different reagents, thrombin times, and dilute Russell's viper venom times (RVVT), or no clot formation occurred, which limited the clinical usefulness of the tests in this species 8 …”